EfficienSea2 - Task 2.6 / D2.6 Report on Space Weather (SW ... · EfficienSea2 -CLS_2 [Nomenclature] V1.0 2017,Oct.27 i. 6 Proprietary information: no part of this document may be

[Catégorie ]

EfficienSea2 - Task 2.6 / D2.6 Report on Space Weather (SW) forecast warning

service

Reference: EfficienSea2-CLS_2

Nomenclature: [Nomenclature]

Issue: 1. 0

Date: 2017,Oct.27

With the participation of Royal Arctic Line

EfficienSea2 - Task 2.6 / D2.6 Report on Space Weather (SW) forecast warning service

EfficienSea2-CLS_2 [Nomenclature] V1.0 2017,Oct.27 i.1

Proprietary information: no part of this document may be reproduced divulged or used in any form without prior permission from CLS. F

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Chronology Issues:

Issue: Date: Reason for change: Author(s)

V1.0 28/09/2017 JJ. Valette

P. Yaya

V. Violante

B. Enjalbert

E. Meunier

People involved in this issue:

Written by (*): Jvalette

P. Yaya

Date + Initials:( visa or ref)

Checked by (*):

Date + Initial:( visa ou ref)

[Checker]

Approved by (*): Date + Initial:( visa ou ref)

[Approver]

Application authorized by (*):

Date + Initial:( visa ou ref)

*In the opposite box: Last and First name of the person + company if different from CLS

Index Sheet:

Context: H2020 Efficiensea 2 project

Keywords: GNSS, AIS, Iridium, polar navigation, ionosphere, space weather

Hyperlink:

Distribution:

Company Means of distribution Names

EfficienSea 2 project P. Andersen (Cobham)

Till Soya Rasmussen (DMI)

Cajsa JerslerFransson (Sjofartsverket)

List of tables and figures




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List of tables:

Table 1. Management of data types .............................................................................. 8

Table 2. Constant message content for transmitted messages from the ship .......................... 8

Table 3. Statistics of satellites and spot beams availability (Oct. 2017) ................................ 1

List of figures:

Figure 1 : Diagram of the system ................................................................................. 6

Figure 2. Main characteristics of the equipments and antennas .......................................... 7

Figure 3. Rack PC with the IHM and all integrated electronic board and equipment boxes ........ 7

Figure 4. Equipment installation ............................................................................... 11

Figure 5 : Monthly mean of solar 10.7 cm radio flux during past 18 years ........................... 13

Figure 6 : Solar flares above C-class during cycle 24 ...................................................... 13

Figure 7 : Monthly mean of Ap geomagnetic index during past 18 years.............................. 14

Figure 8 : Solar flares above C-class during the experiment campaign ................................ 15

Figure 9 : 3-hour geomagnetic Kp index during the campaign .......................................... 15

Figure 10 : Chronology of September 2017 space weather events ..................................... 16

Figure 11 : X9 flare of September 6th as seen by SDO (left) and associated CME, from SOHO coronagraph (right).......................................................................................... 16

Figure 12 : Evolution of solar wind magnetic field, speed and density on September 7th and 8th 2017, measured by DSCOVR ............................................................................... 17

Figure 13. Mary Arctica trip during the campaign and location during the September 2017 magnetic event (port of call at Tasiilaq in Greenland) .............................................. 18

Figure 14. Mary Arctica GPS signal scintillations during the 8th of Sept. Geomagnetic storm .... 19

Figure 15. 8th September magnetic event impact on the GNSS satellites losses of lock (from C-NAV receiver data) ............................................................................................ 1

Figure 16. C-NAV receiver solutions onboard the Mary Arctica ........................................... 1

Figure 17. One second PPP C-NAV GNSS solutions ............................................................ 2

Figure 18. Greenland permanent stations used for testing storm impacts (rnx inter is for RINEX data and date rate) ............................................................................................ 3

Figure 19. Calculated GPS 3D positions and satellites availability (MSVG station) .................... 3

Figure 20. Summary of position errors at permanent sites and fixed antennas (Greenland, previous map) .................................................................................................. 4

Figure 21. L2 links losses of lock on the Mary Arctica ....................................................... 5

Figure 22. L2 losses of lock comparisons at sea (Mary Arctica) and at ground ......................... 5

Figure 23. High latitudes DGPS stations in Alaska based (USCG source) ................................. 6

Figure 24. Time interval between successive AIVD0 messages (before transmission) ............... 7

Figure 25. Zoom in latitude during a 10 s interruption of the AIVD0 messages ....................... 8

Figure 26. Class-B AIS receiver observed horizontal errors (C-NAV solutions as ref.)................ 8

Figure 27. Observed erroneous positions in latitude or longitude – Mary Arctica AIVDM data ..... 9




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Figure 28. Mary Arctica positions errors (with respect to C-NAV GNSS PPP reference solutions) 10

Figure 29. Mary Arctica speed (AIS data source) ............................................................ 11

Figure 30. Iridium terminal (left), satellite constellation and spot beams (right) ................... 12

Figure 31. Iridium SBD service .................................................................................. 12

Figure 32. Iridium service interruption in case of satellite failure (low latitude, worst case) ... 13

Figure 33. Iridium command (left) to analyze the satellite and antenna beams (right) constellation .................................................................................................. 13

Figure 34. Present status of the Iridium satellite Spot Beams (x-axis is sat. Id) ....................... 1

Figure 35. Status of the Iridium satellites (Oct. 2017) ...................................................... 1

Figure 36. Iridium transmission process (left), main commands (right) ................................. 2

Figure 37. Analysis of Iridium connection losses .............................................................. 2

Figure 38. Observed Iridium data transmission perturbations and comparison with GPS perturbations (ROTI index) during the 5-8th Sept. 2017 .............................................. 3

Figure 39. Inmarsat transmission process (left), examples of commands and return status (right) ............................................................................................................. 4

Figure 40. Observed Iridium data transmission perturbations and comparison with GPS perturbations (ROTI index) during the 5-8th Sept. 2017 ............................................. 5

Figure 41. Relief around Tasiilaq Greenland port ............................................................ 6

Figure 42 : GNSS network used to monitor the regional ionospheric activity during the campaign ........................................................................................................ 7

Figure 43 : Regional ionospheric scintillations during the campaign ..................................... 8

Figure 44 : GPS Scintillations regional mean and onboard Mary Arctica between Sept 6th and 7th ................................................................................................................. 9

Figure 45 : Scintillation spatial dynamics during 3 peaks of the event : Sept 7th around 23:20 (top), Sept 8th around 00:25 (middle) and around 17:55 (bottom). Patches propagation are indicated by blue arrows ............................................................................. 10

Figure 46 : GNSS Network used for scintillation model elaboration .................................... 11

Figure 47 : Correlation between ROTI and Bz component of the solar wind ......................... 12

Figure 48 : Correlation between Solar Wind Index (combination of IMF and wind speed) with Kp geomagnetic index ...................................................................................... 13

Figure 49 : Scatter plot of Model ROTI vs Observed ROTI on the whole study period (2011 to 2015) ........................................................................................................... 14

Figure 50 : Model ROTI and Observed ROTI in March 2015 ............................................... 15

Figure 51 : ROTI Map during March 17th 2015 event : observations are yellow to red levels, model is in shades of blue ................................................................................. 15

Figure 52 : ROTI observed (left) and forecast (right) before, during, and after the first phase of 7-8th September 2017 event ........................................................................... 16

Figure 53 : ROTI observed onboard Mary Arctica and ROTI forecast for the ship during Sept 7-8 2015 event .................................................................................................... 17




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Reference documents

Carbary, J. F. (2005), A Kp-based model of auroral boundaries, Space Weather, 3, S10001, doi:10.1029/2005SW000162

Kinrade, J (2013), Ionospheric Imaging and Scintillation Monitoring in the Antarctic and Arctic, PhD thesis, University of Bath.




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List of Contents

1. Special thanks to the Royal Arctic Line Danish Company and to Task 2 leader ........................................................................................... 1

2. Introduction ................................................................................ 1

3. Campaign description and organisation ............................................... 1

3.1. Objectives of the campaign........................................................ 1

3.2. Efficiensea2 news “European project launches Arctic campaign to monitor space weather impact” ........................................................ 2

3.3. Royal Arctic Line Company ........................................................ 2

3.4. Mary Arctica ship description ..................................................... 2

4. Equipment specification and developments, campaign preparation ............ 4

4.1. High level campaign requirements/specifications ............................. 4

4.2. Context diagram of the test equipments system .............................. 5

4.3. Test equipments package .......................................................... 6

4.4. Data management per type ........................................................ 8

4.4.1. Ex. of Argos transmitted messages .............................................................. 8

4.4.2. Ex. Iridium transmitted/received messages onboard ........................................ 9

4.4.3. Ex. of Inmarsat transmitted messages .......................................................... 9

4.4.4. Recorded onboard GNSS messages frame and data ........................................ 10

4.4.5. Recorded onboard AIS data ...................................................................... 10

4.4.6. Data reporting ...................................................................................... 10

5. Mary Arctica ship space weather test campaign (May to October 2017) ...... 10

5.1. Onboard ship installation ......................................................... 10

5.2. Onboard operations ................................................................ 11

5.3. Solar and geomagnetic activity context ........................................ 12

5.3.1. Solar cycle and 5 months context ............................................................. 12

5.3.2. September 4-10 2017 solar and geomagnetic events ..................................... 15

5.4. Analysis of solar and magnetic major event during the campaign ........ 17

5.4.1. Focus on the major 5-8 September magnetic event ....................................... 17

5.4.2. Data analysis methodology ...................................................................... 18

5.5. Analysis of GNSS data .............................................................. 18

5.5.1. References for positions and magnetic event time correlation ......................... 19

5.5.2. C-NAV receiver GNSS signal analysis .......................................................... 19

5.5.3. C-NAV receiver positioning analysis ........................................................... 20

5.5.4. High latitude GPS permanent stations and positioning errors analysis .................. 2

5.5.5. GPS satellite losses at sea versus at fixed stations ........................................... 4

5.5.6. Conclusions on GNSS impacts analysis (C-NAV receiver) .................................... 6

5.6. Analysis of AIS data .................................................................. 6




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5.6.1. Analysis of the Efficiensea2 class B AIS messages (transmission mode) ................. 6

5.6.2. Analysis of the Mary Arctica class A AIS messages (reception mode) .................... 8

5.6.3. Conclusions on AIS impacts analysis ........................................................... 11

5.7. Analysis of Iridium data ........................................................... 11

5.7.1. Iridium satellite constellation................................................................... 11

5.7.2. Satellite links and analysis methodology ..................................................... 12

5.7.2.1. SBD service (Short Burst Service) ........................................................... 12

5.7.2.2. Transmission performances specification and known communication gaps ......... 13

5.7.2.3. Satellite transmission commands and return status ...................................... 1

5.7.3. Mary Arctica data transmission perturbations during the 6 to 8 Sept 2017 ............ 2

5.7.4. Conclusions on Iridium impacts analysis ........................................................ 3

5.8. Analysis of Inmarsat data........................................................... 4

5.8.1. Satellite links and analysis methodology ....................................................... 4

5.8.2. Mary Arctica data transmission perturbations during the 6 to 8 Sept 2017 ............ 4

5.8.3. Conclusions on INMARSAT impacts analysis .................................................... 6

5.9. Scintillations nowcast approach .................................................. 7

5.9.1. Scintillations observation method ............................................................... 7

5.9.2. Ionospheric activity during the campaign ...................................................... 7

5.9.3. September 2017 event analysis .................................................................. 8

5.10. Scintillation forecast approach ................................................. 10

5.10.1. Forecast method ................................................................................. 10

5.10.2. Forecast validation .............................................................................. 13

5.10.3. September 2017 event analysis .............................................................. 15

6. Space Weather forecast warning service prototype ............................... 17

Appendix A - AIS characteristics .......................................................... 18

Appendix B - GNSS characteristics........................................................ 20

Appendix C - Argos characteristics ....................................................... 23

Appendix D - Inmarsat characteristics ................................................... 25

Appendix E - Iridium characteristics ..................................................... 26

Appendix F - Gyroscope characteristics ................................................. 30

Appendix G - UPS characteristics ......................................................... 32

Appendix H - Acronyms ..................................................................... 33


EfficienSea2-CLS_2 [Nomenclature] V1.0 2017,Oct.27 1


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Nota : in that document SW acronym refers to Space Weather

1. Special thanks to the Royal Arctic Line Danish Company and to Task 2 leader

The authors of that document would like to address their specials thanks to the Royal Arctic Line Maritime Company based in Aalborg that provide the perfect conditions for space weather test on equipments at sea in high latitudes. Considering how difficult it is to install new equipments onboard and in our case the number and variety added some complexity and considering the necessary involvement of technical staff. CLS and more generally, DMA the leader of Efficiensea 2 project and all the project members have warmly appreciate such logistic support.

In particular, we want to warmly thank Henrik Rudkjøbing Rasmussen, the Technical Superintendent who had welcome Valentine Violante and Benjamin Enjalbert and regularly sent back external disk of the campaign to CLS premises at Toulouse.

2. Introduction

This document is dedicated to the description of the field space weather test campaign realized at sea on the Mary Arctica, which is a cargo vessel from the Danish maritime company Royal Arctic Line. Specific navigation and communication equipments have been installed onboard in order to observe perturbations due to space weather.

The experiment was lead from May to October 2017.

Note that two previous deliveries of task 2 may help the understanding of that document. They are titled are follows:

- EfficienSea2 - Task 2.2 / D2.5 Report on space weather effects on communication and positioning services – CLS, oct. 2016

- EfficienSea2 - D2-4 Analysis report on available and emerging communications technologies - CLS, Oct. 2015.

3. Campaign description and organisation

3.1. Objectives of the campaign

The objectives of the campaign is to collect relevant parameters related to navigation systems and telecommunications that may be demonstrative of possible perturbations correlated to space weather effects. On the maritime domain, the systems are mainly the GNSS, the AIS, HF, Iridium, and Inmarsat. The space weather effects mainly concern instabilities in the ionosphere, the atmospheric layer between 100 and 1000 km altitude. Because of the proximity of the pole and the connexion to the magnetosphere and the interplanetary medium, the high latitudes (oval auroral and polar caps) present a high complexity of response to the geomagnetic activity.

It is difficult to find observations of perturbations on the previous mentioned systems. As a consequence, quantitative impacts are not known. Therefore, the evaluation of this campaign aims




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at identifying impacts on the individual systems. It is notable that such test campaign is done for the first time.

3.2. Efficiensea2 news “European project launches Arctic campaign to monitor space weather impact”

One can also see the news posted on the project web page.

http://efficiensea2.org/european-project-launch-arctic-campaign-to-monitor-space-weather/

3.3. Royal Arctic Line Company

The Government of Greenland has given Royal Arctic Line A/S an exclusive concession for the transportation of all sea cargo to and from Greenland and between the Greenlandic towns and settlements. The shipping company is Greenland’s lifeline, ensuring supplies to the entire country. All the towns on both the East Coast and the West Coast are regularly connected to Denmark.

Royal Arctic Line A/S was founded in 1993 and it is wholly owned by the Government of Greenland.

The company has a fleet of 13 vessels, part as container ships, part as settlement vessels.

3.4. Mary Arctica ship description

Mary Arctica is a 113,0 m long container vessel with a capacity of 372 TEU. Crew is composed of 1 captain, 8 officers, 7 crew persons, 1 doctor. Some vessel identification parameters, in particular useful for the AIS, are as follows:

- IMO 9311878, - MMSI : 20364000, - Call Sign




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4. Equipment specification and developments, campaign preparation

4.1. High level campaign requirements/specifications

Some high level requirements and specifications of the test campaign have been written. The most relevant have been listed in that chapter. They were important to establish as they impact the choice of the material, the design of the rack in which all the electronic boards are included and the processor that pilot the data management and individual equipment configuration.

Equipment list and frequency bands

Navigation : AIS (VHF), GPS (L band)

Communication : AIS (VHF), Iridium (L-band), Inmarsat (L-band)

Data collection : Argos (UHF)

System management

The complete test system shall be autonomous. A processor shall manage all the equipments and related data (configuration, acquisition, monitoring, storage...).

No routine action is required from the crew except when Mary Arctica is at quay in Aalborg, typically every 3 weeks (agreement with the superintendent).

A remote control of the system shall be available (Iridium solution adopted) from CLS premises.

Each part of the equipment shall be configurable individually.

Data protocol

The objective of the campaign has been dedicated to the detection of system operation anomalies. To do that, permanent transmissions would have been the ideal situation. For each system, a trade-off has been designed and implemented. An optimal transmission rate has been defined, generally around one per minute.

The content of the message is defined constant during all the campaign as the focus is put on the transmission performance and not the included information.

Onboard data management

The data here includes both those collected by the equipments (AIS, GPS, Iridium for aknowledge or satellites constellation status) but also those transmitted (Argos, Iridium, Inmarsat). All data are copied on a local disk and simultaneously on an external disk.

Remote control of transmitted data

All transmitted data (Iridium, Inmarsat, Argos) are collected at CLS data processing centre. It is checked that a continuous reception is effective during the test campaign.

Constraints

All the boxes and electronic boards that composed the monitoring system (except antennas) including the processor that manages all the system shall be packaged in a compact rack. A graphical interface (IHM including a screen, a keyboard and SW) is required for the configuration, control and validation of the system application.




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The ship constraints shall be considered. They concern the rack installation inside and also the antennas installation (see later on the complexity of tasks). The cable lengths were also taken into account in order to avoid too much power losses. This was compensated with a selection of high quality. The system will be powered by the ship's power, 220V AC. The system will meet the constraints of the environment in which it will be placed (UV, vibrations, shocks, oxidations resistant).

The system will be independent of the equipment of the vessel on which it will be placed.

Operations

An important requirement is that the monitoring system shall operate continuously during the period of the campaign. This was considered a critical design parameter as the space weather events can’t be forecast with a high level of confidence. Thereforeit is preferable to collect data continuously.

Minimum assistance or maintenance is required from the vessel crew. It is limited to the extraction of an external disk and replacement with a new one when at berth in Aalborg. A guideline as simple as possible, has to be written for the technical staff onboard (see also following chapter 5.2).

Campaign duration

The Mary Arctica arrived from Antarctica in May. A few months of tests seem reasonable expecting that some magnetic events occur during the period. The test campaign was possible from end of May to October 2017.

4.2. Context diagram of the test equipments system

The context diagram of the complete space weather monitoring system is given hereafter.




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4.3. Test equipments package

After analysis of requirements and constraints, an optimal selection has been done for each part of the equipment. The final system package consists of :

- a rack-mountable PC - an AIS receiver : Raymarine AIS 650 - a GPS/GNSS receiver: C-Nav 3050 (multi-constellations and PPP compatible, see also

chapter 5.5) - an Argos transmitter : HAL 2 - an Inmarsat transmitter : IDP 690 - Iridium transmitters : Modem 9523, Modem 9602, Triton Beacon - a gyroscope : Yost-lab - a UPS: ellipse pro 850 Eaton.

The following figure shows a summary map of the equipment that composed the test material package. More details about each equipment are given in annexes.

Figure 1 : Diagram of the system




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Figure 2. Main characteristics of the equipments and antennas

The developed rackable PC is shown hereafter.

Figure 3. Rack PC with the IHM and all integrated electronic board and equipment boxes




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4.4. Data management per type

The rackable PC also called the “Efficiensea2 machine” is mainly composed of all the experiment subsytems (AIS, GNSS, ARGOS, IRIDIUM, INMARSAT, Gyroscope) and a controller system (IRIDIUM controller) and the processor. The controller system is handling acknowledgements transmission.

A SW application has been developed to manage all the system. A specific data management is designed for each equipement. The following table presents the naming of the different types of messages transmitted from the ship. To avoid too high file volume a specific strategy has been specified for each type.

Table 1. Management of data types

The content of the messages data for Argos, Iridium and Inmarsat are constant as follows:

Table 2. Constant message content for transmitted messages from the ship

4.4.1. Ex. of Argos transmitted messages

Filename

Mary-Arctica\Data-170724-113359\data\argos\20170520-105622_argos.dat

Content

[Date] header Fixed Argos Data

[2017-05-11 11:52:26.195] S01,M01,T33,12132,803,26,FFFE2FFD22DD55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA

[2017-05-11 11:53:27.198] S01,M01,T34,12132,804,26,FFFE2FFD22DD55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA55AA

The frame of Argos messages sent are of 5 bytes.




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4.4.2. Ex. Iridium transmitted/received messages onboard

MO: Mobile (Modem) Originated (Tx from the ship)

MT: Mobile (Modem) Terminated (Rx from the ship)

The content is a list of Iridium commands and results of the command as illustrated hereafter

Filename

Mary-Arctica\Data-170724-113359\data\iridium\20170616-202842_iridium.dat

Content (file extract)

[2017-05-11 11:31:23.762] ATE1

[2017-05-11 11:31:23.765] OK

[2017-05-11 11:31:23.765] AT+CIER=0,0,0,0,0

[2017-05-11 11:31:23.765] OK

[2017-05-11 11:31:23.765] ATQ0

[2017-05-11 11:31:23.838] +SBDS: 0, 60670, 0, -1

[2017-05-11 11:31:43.069] AT+SBDIX

[2017-05-11 11:31:43.085] +SBDIX: 32, 60670, 2, 0, 0, 0 32 : command status

[2017-05-11 11:31:44.086]

[2017-05-11 11:31:44.086] OK

[2017-05-11 11:31:44.086] +CIEV:3,80,45,0,3364,640,5360

[2017-05-11 11:32:34.525] +CIEV:3,80,46,0,3444,652,5304

[2017-05-11 11:32:35.527]

AT+SBDWT=UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU

UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU (Fixed Iridium Data)

4.4.3. Ex. of Inmarsat transmitted messages

The content is a list of Inmarsat commands and results of the command as illustrated hereafter

Filename

Mary-Arctica\Data-170724-113359\data\argos\20170520-105622_inmarsat.dat

Content

[2017-06-10 07:23:29.664] ATE1

[2017-06-10 07:23:29.671] OK

[2017-06-10 07:23:29.671] ATQ0

[2017-06-10 07:23:29.688] ATV1

[2017-06-10 07:23:29.703] AT%TRK=1,1

[2017-06-10 07:23:30.726] ATS89?

[2017-06-10 07:23:30.726] 00016

[2017-06-10 07:23:31.886] AT%GPS=1,1,"GGA","RMC","GSA","GSV"

[2017-06-10 07:23:31.895] ERROR

[2017-06-10 07:23:31.902] AT%MGRS

[2017-06-10 07:23:31.936] %MGRS: "test",0.0,1,184,4,15,0

[2017-06-10 07:23:31.995] AT%MGRC="test"

[2017-06-10 07:23:31.995] OK




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[2017-06-10 07:23:32.114] AT%MGRT="test",1,184.0,1,"UUUUUUUUUUUUU" (fixed Inmarsat data)

[2017-06-10 07:24:32.218] AT%GPS=1,1,"GGA","RMC","GSA","GSV"

[2017-06-10 07:24:32.301] %GPS: $GPGGA,072409.000,5702.9160,N,01003.4637,E,1,08,0.8,24.6,M,42.3,M,,0000*6B

[2017-06-10 07:24:32.376] $GPRMC,072409.000,A,5702.9160,N,01003.4637,E,0.03,0.00,100617,,,A*6E

4.4.4. Recorded onboard GNSS messages frame and data

• Data logged from GNSS are :

- NCT Binary messages (almanach, ephemerides, measurements, channel status, PVT, pseudoranges…) -NMEA messages (all types)

• Data from GNSS are logged in raw format. These raw data can be converted in RINEX format for post processing especially for vessel positioning.

• GNSS receiver is configured to collect raw data at 1 Hz.

4.4.5. Recorded onboard AIS data

Both the AIS messages generated by the Mary Arctica (!AIVD0 msg) and those collected onboard and coming from other ship in its vicinity (!AIVDM msg) are collected and stored onboard by the Efficiensea2 application.

• Data format from AIS are NMEA 0183 frames.

4.4.6. Data reporting

Data reports are sent automatically once a day at a specific hour. The data report includes:

- date/hour of last file modification,

- file size,

- free space on the two hard drives,

- status of each equipment/system.

5. Mary Arctica ship space weather test campaign (May to October 2017)

5.1. Onboard ship installation

The equipment installation was done during a couple of days with the valuable technical and logistic support of the Royal Arctic line team.




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Figure 4. Equipment installation

5.2. Onboard operations




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5.3. Solar and geomagnetic activity context

5.3.1. Solar cycle and 5 months context

The main impacts expected on the equipment tested onboard Mary Arctica are related to ionosphere perturbations, themselves linked to geomagnetic activity. The solar sources of geomagnetic activity are multiple: solar flares and coronal mass ejections can lead to the strongest events, but coronal holes also play an important role and are the origin of the most frequent geomagnetic perturbations. On a long term perspective, all of these solar phenomena are modulated by the 11-year quasi-periodic solar cycle. The current one, solar cycle 24, began in 2009, reached a moderate maximum in 2014 and is now well advanced in its declining phase. This is typically illustrated by the 10.7 cm solar radio flux, but also affects the frequency and intensity of flares.




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Figure 5 : Monthly mean of solar 10.7 cm radio flux during past 18 years

Figure 6 : Solar flares above C-class during cycle 24

The geomagnetic activity follows a slightly different pattern, the cycle pattern being shifted 1 to several years later than for the solar activity. For cycle 24, the smoothed maximum of geomagnetic activity occurred in 2015, and it has not yet clearly entered its declining phase.




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Figure 7 : Monthly mean of Ap geomagnetic index during past 18 years

The experiment campaign began in May 2017 in a context of low solar activity and moderate geomagnetic one, but in September, the activity significantly diverged from the long term trend. It has already been observed in the past, like for example in 2005 or 2006, significant space weather events well advanced in the declining phase of a solar cycle. The events of early September 2017 are another remarkable example of the short term irregularity of solar activity. Several complex sunspots formed at the surface of the Sun and produced the strongest flares of whole solar cycle 24 (i.e. of the 10 past years), followed by a powerful CME, that produced the second strongest geomagnetic storm of the cycle. (details are given in the next chapter).

When considering only the time period of the campaign, from May to October 2017, it is even clearer that the solar flaring has been essentially low except for the spectacular burst at the beginning of September, with the 2 strongest flares reaching X9 and X8 levels (Figure 8), on September 6th and 10th respectively, as measured by GOES satellites. The geomagnetic activity subsequent to the X9 flares was logically the strongest of the period, with a maximum geomagnetic Kp Index of 8, according to GFZ1, but several moderate events with Kp up to 6 and 7 occurred, especially in May and end of September (Figure 9).

The event of early September being stronger by all aspects than any other during the campaign, the impacts analysis have been mainly focused on this one.

1 http://www.gfz-potsdam.de/en/kp-index/




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Figure 8 : Solar flares above C-class during the experiment campaign

Figure 9 : 3-hour geomagnetic Kp index during the campaign

5.3.2. September 4-10 2017 solar and geomagnetic events

The events of early September 2017 originated in the solar active region numbered 12673 by NOAA/Space Weather Prediction Centre: it began to rapidly develop starting from September 3rd, and produced a series of strong flares between September 4th and 10th, before it rotated outside of Earth visibility. Three of the main flares were associated with CMEs (coronal mass ejections), and with energetic particles. The most important CME from an Earth point of view was ejected during the X9 flare of September 6th, producing the main geomagnetic storm of the period on September 7th and 8th. Another CME was ejected during the X8 flare of September 10th, but was essentially not Earth-directed. This last flare was also the source of a major proton event until September 12th. Solar proton events, by precipitating into the polar cap, can enhance the D-layer of the ionosphere and produce abnormal absorption of long range HF radio communication. These effects were unfortunately not investigated during the experiment campaign. During the data analysis, the focus was made on the geomagnetic storm of Sept. 7-8th.




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Figure 10 : Chronology of September 2017 space weather events

Figure 11 : X9 flare of September 6th as seen by SDO (left) and associated CME, from SOHO coronagraph (right)

The level of geomagnetic activity is related to the solar wind characteristics, in particular of the interplanetary magnetic field (IMF) carried by the solar wind. It is continuously monitored in real time by several space probes located at the Lagrange point L1, which is 1.5 millions of km away from the Earth in direction of the Sun, and allows an observation of solar wind 30 minutes to 1 hour before it effectively reaches the Earth. The main parameter of the solar wind linked to geomagnetic activity is the vertical component of the IMF, called “Bz”: in simple terms, the more it drops to large negative values, the more intense geomagnetic activity is expected to be.

The impact of the CME bow shock at L1 is clearly visible at 22:30 UT on September 7th by a sudden drop of from -10 to -25 nT, and a sudden increase in the solar wind speed from 400 to 700 km/s. This first phase of the storm lasted until around 1 to 2 UT on Sept, 8th and a second active phase occurred on Sept 8th starting on 11 UT and progressively decaying in the evening. These 2 phases visible in the solar wind characteristics are were reproduced in the evolution of geomagnetic indices.




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Figure 12 : Evolution of solar wind magnetic field, speed and density on September 7th and 8th 2017, measured by DSCOVR

5.4. Analysis of solar and magnetic major event during the campaign

5.4.1. Focus on the major 5-8 September magnetic event

According to the objectives of the campaign, the most relevant information to exploit is a period of few days around the September magnetic event. The 5 to 7 of September will provide nominal situation of the RF environment while the 8th will provide perturbed RF environment (as shown in chapter 0).

The following map shows where the Mary Arctica was navigating during that period. Note that she was at berth on Greenland on the 8th.




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Figure 13. Mary Arctica trip during the campaign and location during the September 2017 magnetic event (port of call at Tasiilaq in Greenland)

5.4.2. Data analysis methodology

For each of the navigation and communication monitoring systems, the methodology of the data analyses is a two step process. First is to identify and to quantity typical key parameters that reflects the nominal performances associated to each process. The 5-7 of September or any other period without environment perturbations can be used for that purpose. Second is to identify, during the perturbed period of 8th of September, the perturbations of the key parameters and if possible to quantify them.

Such key parameters may be internal to the system like the losses of parts of the GNSS satellites constellation. Such parameters may also be analysed to quantify, when possible, the impact for user (position errors for example or service interruptions), in our case the mariner.

In the case of positions impact analysis based on GNSS and AIS data, the C-NAV PPP receiver will give the 3D absolute reference coordinates.

5.5. Analysis of GNSS data

The approach of the space weather analysis of GNSS data of the C-NAV receiver data during the 5 to 8 September 2017 magnetic event will be driven by the following objectives:

- Identify/quantify possible losses of GNSS satellite tracking, - Identify/quantify signals perturbations,




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- Identify/quantify GNSS/PPP service interruption (eventually due to the Inmarsat connection perturbations for the PPP corrections transmission),

- Identify/quantify induced positioning errors – if any.

5.5.1. References for positions and magnetic event time correlation

The analysis of GNSS data is the first step of all the space weather data processing. The first reason is that the GNSS signal perturbations may be analyzed very finally at 1 second rate and they provide information from various regions of the space. A mapping is also possible (see also chapter 5.9 Error! Reference source not found.). The second reason us that the GNSS C-NAV solutions are very precise/accurate and can be used as absolute reference to the other positions derived from GPS especially in the AIS position reports.

In effect, the GNSS receiver is compatible with GPS and Glonass signals. It also has the capability to receive GNSS corrections transmitted from Inmarsat satellite. Such corrections are related to GPS satellite ephemerides and clocks but also to ionospheric perturbations due to TEC variability. The corrections are received on board and digested in real time by the C-NAV GNSS receiver. A PPP – Precise Point Positioning – is then available offering solutions with precision much under 1 m. The C-NAV service is described in https://www.oceaneering.com/positioning-solutions/

5.5.2. C-NAV receiver GNSS signal analysis

The GNSS phase data are used to point out signal scintillations. The ROTI index which represents statistics on fast fluctuations on the electronic contents that disturb the GNSS rays is used (see also D2.5 previous document). ROTI is calculated every 5 minutes for all satellites. 1st quartile of ROTI is plotted as an indicator that a large portion of the satellite constellation – that is to say a large part of the sky – is affected. The 3rd quartile indicates relative peaks intensity in time.

Figure 14. Mary Arctica GPS signal scintillations during the 8th of Sept. Geomagnetic storm




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Such figure is then relevant as a possible time reference of magnetic perturbations on the 8th of September. It will be used in the next steps for time correlations analysis.

5.5.3. C-NAV receiver positioning analysis

From the raw data collected on the rack, we have extracted the C-NAV receiver data, concatenated the 4 days files and convert them into the international RINEX (Receiver Independent Exchange) format. First investigation concerns satellites losses of lock. One can see that on the 8th of September, up to half of the satellite constellation is lost at worst during several minutes. It is interesting to see that both the GLONASS and the GPS constellation present the same behaviour at the same time. The number of functional GPS satellites is reduced to 3 or 4 which may be critical for calculating a 3D position of the antenna.



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Figure 15. 8th September magnetic event impact on the GNSS satellites losses of lock (from C-NAV receiver data)




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Antenna positions solutions at 1 second rate have been derived from the RINEX files.

The next figure corresponds to the latitude, longitude and height variations during the 7th and 8th of September. One can see that the vessel is at berth in Tasiilaq (65° 36′ 55″ N, 37° 38′ 15″ W) from about 9:00 am to 10:00 pm in Greenland.

Figure 16. C-NAV receiver solutions onboard the Mary Arctica

To have an idea of the relative precision of the solutions a high-pass filter is applied to those time series with a cut-off period of 1 mn. Results are plotted hereafter. One can clearly see the impact of navigation conditions (blue line) when comparing to the ship at berth (red lines). The first case provides around ±1 m scattering with a maximum of ±3 m while static positions are within ±0.1 to ±0.5 most of the time. Specifications says that PPP worldwide accuracy is better than 5 cm - at one sigma within adequate Inmarsat and global navigation satellite system (GNSS) satellite visibility.

The observed precision degradation at a few decimeters level at berth may be induced by the magnetic conditions however it is not useful to go in further detail in the scope of the Efficiensea 2 project as PPP is marginal and not at all the issue of a mariner when considering safety of navigation.




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Figure 17. One second PPP C-NAV GNSS solutions

(high-pass filter applied with a cut-off period of 1 min)

5.5.4. High latitude GPS permanent stations and positioning errors analysis

In order to go further on the GNSS positioning induced errors we have analyzed 6 Greenland permanent stations (map on the next figure). Analysis of losses of GPS satellites have been observed and time series of positions have been calculated. Results are plotted hereafter.

One will see that at high latitude, the number of GPS stations varies a lot with time and a configuration with 5 satellites which is not favourable is quite frequent. The positioning error impact of the storm may be seen for some stations but is not significant in most of the cases for fixed antennas.




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Figure 18. Greenland permanent stations used for testing storm impacts (rnx inter is for RINEX data and date rate)

Figure 19. Calculated GPS 3D positions and satellites availability (MSVG station)




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Figure 20. Summary of position errors at permanent sites and fixed antennas (Greenland, previous map)

The following chapter intents to complete this statistics with observations at sea on the Mary Arctica.

5.5.5. GPS satellite losses at sea versus at fixed stations

The two following figures present the comparison results on L2 signal losses of lock in case of the Mary Arctica C-NAV receiver and permanent ground stations during the storm peak on the 8th of September.




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Figure 21. L2 links losses of lock on the Mary Arctica

Figure 22. L2 losses of lock comparisons at sea (Mary Arctica) and at ground




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5.5.6. Conclusions on GNSS impacts analysis (C-NAV receiver)

It has been observed that up to 50% of the satellite constellation may be lost during short periods of time of about a few minutes. The nominal PPP precision based on GPS+Glonass is degraded from nominal 5 cm specification in horizontal up to several tens of cm.

When considering a single constellation without PPP corrections and static antennas at permanent ground stations, several meters errors can be observed however they are not systematic. Moreover, such errors are on the same order of magnitude of errors that are observed when a change occurs on the satellite constellation.

Having the information that possible few meters errors may occur can be considered as relevant in case of e-navigation when using DGPS delivered via AIS coastal station. In Alaska, for example, the U.S. Coast Guard Navigation Center operates part of the National DGPS service based on 38 coastal broadcast stations to improve the accuracy and integrity to GPS-derived positions up to typically 1 to 3 meters (next figure).

Figure 23. High latitudes DGPS stations in Alaska based (USCG source)

5.6. Analysis of AIS data

From the AIS class B receiver which has specially been installed by CLS on the ship (see also 4.4.5) several analyses of the AIS data collected are possible. One concerns the AIS class B messages that are collected before their transmission. Another source is the received messages from the other ship and among them the Mary Arctica. We have focussed the investigation on positions contained in the positions reports. The C-NAV PPP solutions are used as absolute reference positions.

5.6.1. Analysis of the Efficiensea2 class B AIS messages (transmission mode)

The concerned messages are the AIVD0 (as detailed in chapter 4.4.5). First check to be done on such data is to verify that the AIS positions reports (PRs) are properly generated over time. We




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could imagine that in case the GPS receiver is not able to provide a position the message may not be built (without any confirmation of such assumption).

To do so, we have calculated the time difference between two successive AIVD0 messages. In effects, such parameter will permit to point out possible GPS service interruptions assuming that the AIS message is not delivered in case of GPS failure. The results are shown in the newt figure. It appears that the time interval between two PRs is most of the time 2 seconds (). Two intervals around 10 seconds have been observed but can’t be correlated with the environment.

Figure 24. Time interval between successive AIVD0 messages (before transmission)

The reason of such outliers is not understood, the hereafter map shows the latitude of the ship when they occurred.




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Figure 25. Zoom in latitude during a 10 s interruption of the AIVD0 messages

So as first conclusion, it seems that the Class-B receiver is continuously operating during the event.

According to the positions that are included in the position reports, comparisons have been done to the C-NAV solutions and plotted in the next figure. Note that some time and antennas distance biases adjustment have been done in the comparison.

Figure 26. Class-B AIS receiver observed horizontal errors (C-NAV solutions as ref.)

The class-B receiver position errors are reflected with the mean difference and scattering in the comparisons. Ten meter is the classical natural present GPS precision and it is then coherent to the expectations. We didn’t see so much high error values. The one which is observed late on the 7th and also late on the 8th may be due to a satellite constellation change which is quite constant from one day to another when seen from the same area.

5.6.2. Analysis of the Mary Arctica class A AIS messages (reception mode)

From the class-B AIS receiver, we have extracted the received PRs coming from the Mary Arctica class-A receiver. Taking into account the AIS protocol and more precisely the imposed AIS data rate as a function of the velocity, we didn’t see any anomaly on the message generation.

According to the positions, we firstly identify two clear false positions over the period. Each one is apparently due to erroneous latitude or longitude values and not simultaneously. It is probably due to erroneous transmitted bits on the messages. However this is can be considered as marginal and not connected to our purpose.




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Figure 27. Observed erroneous positions in latitude or longitude – Mary Arctica AIVDM data

The next step consists in calculating and plotting the Mary Arctica AIS positions with the C-NAV PPP solutions. Some adjustment has been made in order to compensate the antenna distances. It is then interesting to analyse the general behaviour of the differences in North, East and on the horizontal plan (Figure 28). Some observations can be easily interpreted some are more difficult to understood without further investigation. First observation is that when the Mary Arctica is at berth on the 8th of September for a couple of hours, the scattering of the time series is very low and reduced to a few meters. This is consistent with the GPS precision for a non mobile antenna without sky mask which is the case on the ship bridge. As a consequence, the plot scattering which is observed during the other part of the time span may reach 20 m on the 5th and 6th and a sudden change on the 7th at a 40 m up midday. This is not presently explained.




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Northing differences (AIVDM – C-NAV)

Easting differences (AIVDM – C-NAV)

Horizontal errors (AIVDM – C-NAV)

Figure 28. Mary Arctica positions errors (with respect to C-NAV GNSS PPP reference solutions)

An assumption for the strange behaviour of errors jump from 20 to 40 m on horizontal is a time stamp error on the AIS messages that potentially cumulates with the errors induced by the ship displacement and the sea state. The error may then be increased with the ship velocity which is not the case as shown in the speed over ground plots (Figure 29).




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Figure 29. Mary Arctica speed (AIS data source)

At this stage what is important is that no significant signal on the errors scattering that may be correlated with the magnetic event is observed.

5.6.3. Conclusions on AIS impacts analysis

The conclusion is that neither the class-B receiver and the Mary Arctica class-A receiver seem to be significantly impacted by the space weather perturbations in terms of GPS positions errors or the AIS PR message generation.

5.7. Analysis of Iridium data

5.7.1. Iridium satellite constellation

The L-Band Iridium satellite communication system is based on a constellation of 66 LEO satellites organized on 6 orbit plans with 11 satellites per plan. Each satellite covers 4700 km decomposed of 48 spot beams each one including around 400 km at ground. Inter-satellite links and 11 gateways are used to achieve real time communications.

Iridium Next, the second-generation program started in 2017 with three launches in January, June and October providing each 10 more satellites to fully renew the constellation, some satellites being out of use.




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Figure 30. Iridium terminal (left), satellite constellation and spot beams (right)

5.7.2. Satellite links and analysis methodology

5.7.2.1. SBD service (Short Burst Service)

Iridium provides voice and data. In the case of the Mary Arctica, transceiver units based on Iridium modem have been used. Such device supports Short Burst Messages (SBD) are dedicated to M2M services. The following figure illustrates the principle SBD communication links.

Figure 31. Iridium SBD service




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5.7.2.2. Transmission performances specification and known communication gaps

The SBD messages have a maximum of 340 Bytes when originated from the mobile. The specification for the transmission latency is between 5 s up to 20 s depending on the message length. The probability of transmission success (message lost, erroneous content, other origin...) is estimated to be 0.01%, assuming a nominal and 100% operational satellite constellation.

Some known communication gaps are already known. They mainly concern satellite complete failure or partial failure. Partial failures are associated to anomalies on the antenna spot beam operations.

As an example, the following figure shows a possible interruption of Iridium service over 10 to 15 mn due to a satellite failure. Note that the probability that such situation occurs at high latitude is quite low due to the polar LEO orbits. In effects, the ground overlapping of satellite footprint increase with the latitude and the switch from one satellite to another is possible. However, such process details are not known. The analysis of several weeks of data has shown that such situation has not been encountered during the campaign.

Figure 32. Iridium service interruption in case of satellite failure (low latitude, worst case)

It is then important to distinguish communication perturbations related to the present limitations of the Iridium system (satellite gaps or failures) and to those possibly generated by the ionospheric environment. To do that a specific command is send to the system to get the real time status of the Iridium constellation and of every satellite spot beam. That command permanently listens to the Iridium downlink messages coming from the system itself (see also chapter 4.4.2).

Figure 33. Iridium command (left) to analyze the satellite and antenna beams (right) constellation

The result of such command is provided in the following figures.



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In this figure we have plotted the satellite beam status. For each satellite (X axis) the satellite identification number, a dot indicates, on the Y axis, that the spot beam is in operation. No dot indicates an anomaly. The colour choice is arbitrary and mainly helps for a quick view and analysis of the plot.

Figure 34. Present status of the Iridium satellite Spot Beams (x-axis is sat. Id)




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Some statistics of the satellite and spot beams availability are reported hereafter.

Satellites Spot Beams

65/66 2804/3168

98,4% 88,5%

Table 3. Statistics of satellites and spot beams availability (Oct. 2017)

The following table complete the analysis of the constellation status when considering the various orbit plans.

Legend:

- Red is for satellites failures - Green is for Iridium Next (4 Oct. launches not yet considered, they will renew the plan 4)

- Yellow is for satellite gaps

Figure 35. Status of the Iridium satellites (Oct. 2017)

Observations show that failed satellites may generate few minutes of service interruption.

5.7.2.3. Satellite transmission commands and return status

The Iridium transmission process is summarized in the next figure.

The link is bi-directional

First phase is communication session opening and listening:

(sat. synchro., freq. managt…)

Second phase (If successful session) is data transmission

Third phase is session closing

(command status are collected at each steps)

[2017-09-08 21:54:19.870] AT+SBDWT=UUUUUUUUUUUUUUUUUU Buffer writing of the data to transmit [2017-09-08 21:54:19.873] OK [2017-09-08 21:54:23.638] AT+SBDIX SBD Session opening [2017-09-08 21:54:23.652] +SBDIX: 0, 5206, 0, 0, 0, 0 Command status [2017-09-08 21:54:23.653] [2017-09-08 21:54:23.656] OK Buffer cleaning [2017-09-08 21:54:23.671] AT+SBDD0 [2017-09-08 21:54:23.672] 0 [2017-09-08 21:54:23.673] [2017-09-08 21:54:23.675] OK




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[2017-09-08 21:54:24.187] +CIEV:3,37,25,0,2784,-1844,5412 Command to get the constellation status

Figure 36. Iridium transmission process (left), main commands (right)

5.7.3. Mary Arctica data transmission perturbations during the 6 to 8 Sept 2017

The methodology of the Iridium data transmission analysis is based on the return status of the commands used (see also Figure 36). We have focused the analysis on the period of the 5 to 8 of September 2017 because of the most significant ionospheric event faced during the complete observation campaign. The 5 and 6 of September can be used as referenced days without any space weather environment effect. Those two days are representative of calm days and reflect the situation of any other period of the campaign.

Analysis of occurrences of losses of connection – it is verified that the origin of the perturbation is not the Iridium system (satellite and spot beam are properly functional)

Figure 37. Analysis of Iridium connection losses

This first level of analysis seems to show some possible perturbations on the 7th and 8th of September. However, it is useful to go deeper in the analysis. To do that, we have correlate the observed Iridium effects with those on GPS (ROTI index) versus time. Also it is also appear relevant to estimate the duration of the perturbation and try to derive (if possible) quantitative parameters of the service interruption.

The following presents time series of GPS perturbations, the ROTI being the Space Weather proxy. A mean value is calculated every 5 mn (red & yellow dots) all the satellites available. What distinguish the red (3rd quartile) and orange (1st quartile) plots is indirectly a statistical correlation with the regions of space that is affected by scintillations. High Orange dots are associated to the biggest impacted areas. One can see in the figure that the major GNSS scintillations effects are concentrated on the 8th of September.

The figure also includes synthetic Iridium perturbation results plotted as a) time series over 1-hour interval of the ratio of successful transmission and b) the duration of the transmission perturbation.




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Figure 38. Observed Iridium data transmission perturbations and comparison with GPS perturbations (ROTI index) during the 5-8th Sept. 2017

One can see that the ratio of successful transmission has been decreasing from few % up to 50 % during the beginning of the space weather event around midnight the 7th. The perturbation last up 15 mn. However, one can also observe that surprisingly, the Iridium transmission, were not affected by the perturbed ionospheric conditions during the rest of the day on the 8th.

One explanation may be due to the fact that the GPS ROTI index reflects the perturbations over various region of the sky while the Iridium test is limited to one direction of the sky. However, contrary the GPS MEO orbits where the geometry seen from the ship antenna is quite stable over hours, in the case of Iridium LEO orbit, the satellite cross a large angle of the sky during their pass over the antenna.

5.7.4. Conclusions on Iridium impacts analysis

Some communication perturbations are observed during the storm. They affect 50% of the communications and have last more than 15 mn. However, they are not systematic and the correlation is not demonstrated without ambiguity. It is then not possible to draw a clear conclusion on the Iridium communication impact of the ionospheric perturbations.




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5.8. Analysis of Inmarsat data

5.8.1. Satellite links and analysis methodology

The approach and methodology is basically the same as the one applied for the Iridium data analysis. The following figures indicates the transmission process and the main commands/return status involved.

[2017-09-03 22:43:26.855] AT%MGRS From-Mobile Message State [2017-09-03 22:43:26.888] %MGRS:test",5.0,1,184,5,15,0 Fith param is 6 if transmission is finished, 5 if still on going [2017-09-03 22:43:26.888] [2017-09-03 22:43:26.888] OK [2017-09-03 22:42:26.384] %MGRT="test",1,184.0,1,"UUUUUUUUUU" This command sends a from-mobile message from the IDP modem to the gateway [2017-09-03 22:42:26.384] OK ATS89? This command returns a bit map of status conditions that resulted in the assertion of event Notification hardware signal

Figure 39. Inmarsat transmission process (left), examples of commands and return status (right)

5.8.2. Mary Arctica data transmission perturbations during the 6 to 8 Sept 2017

The next figure shows the most relevant observed perturbations during the storm period. As previously used for Iridium, the GNSS ROTI indices are reported to visualize the main event versus time. What is plotted according to Inmarsat is failure on the data transmission and repeated attempts without success. What is observed is that coincidently with the highest GNSS peak of perturbations no Inmarsat communication is possible. It is however puzzling to see that the previous perturbations between the 7th 10:00 pm and the 8th 8:00 am very few perturbations is seen.




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Figure 40. Observed Iridium data transmission perturbations and comparison with GPS perturbations (ROTI index) during the 5-8th Sept. 2017

Moreover, the ship is at berth on the 8th it is then relevant to investigate if there is no physical mask that may degrade the Inmarsat communications. The relief configuration around Tasiilaq has been found in Internet and shown hereafter. A 900 m altitude mountain is visible on the South South-West direction. In a rough estimation, at 66°N a geostationary satellite is visible around 15° (spherical Earth) over the horizon while the peak is estimated to be at 11° elevation. That can’t be the only factor when we consider that the ship was already in the port between 2:00 and 4:00 pm while few Inmarsat transmission perturbations were observed.




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Elevation map around Tasiilaq

Picture of the mountain in the SSW direction

Figure 41. Relief around Tasiilaq Greenland port

5.8.3. Conclusions on INMARSAT impacts analysis

Interruptions of the INMARSAT communications have been observed during the highest intensity of the storm event (GNSS signal scintillations being the reference). Communications were completely blocked during several hours which seem surprisingly long. It is difficult to be sure that the storm was at their origin.




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5.9. Scintillations nowcast approach

5.9.1. Scintillations observation method

The state of the ionosphere regarding GNSS applications can be monitored continuously using GNSS permanent stations, whose data are freely available in real- or near-real time. The main concern in high latitudes regions for L-band trans-ionospheric radio communications such as used by GNSS are signal phase scintillations due to electron precipitation in the auroral oval. A representative and easy to compute indicator of ionospheric scintillations is the Rate of TEC Index (ROTI), which depicts the fast fluctuations of integrated electron content along each line of sight. Mathematically speaking, its formula is given by :

�� = � ��(1 − 2)�� Where

1��2 are the carrier phase observations on the first and second frequency respectively

� is the standard deviation, taken typically on 60 samples for receivers with a 1s observation rate, and 10 samples for receivers with a 30s observations rate.

5.9.2. Ionospheric activity during the campaign

During the experiment campaign, independently from the measurements onboard the Mary Arctica, we used a network from 40 permanent GNSS stations belonging to IGS, EUREF, CORS and GNET network, and distributed between Northern Canada, Arctic regions and Northern Europe to monitor the ionospheric activity.

Figure 42 : GNSS network used to monitor the regional ionospheric activity during the campaign




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Data obtain from these stations confirm the close relationship between high latitude ionospheric scintillations and geomagnetic activity, since time series of 5-min mean ROTI and daily mean ROTI shown in Figure 43 are consistent with Kp index during the same period shown in Figure 10 Error! Reference source not found.. The 5-min scintillation maximum as well as the daily maximum of the period both occurred during the main event, on September 8th. Several occurrences of moderate scintillations were also observed in May, September and October.

Figure 43 : Regional ionospheric scintillations during the campaign

5.9.3. September 2017 event analysis

If September 7-8th event was the strongest scintillation occurrence of the campaign at the regional scale, the event also significantly affected GPS data acquired onboard Mary Arctica, at the local scale.

Low to moderate scintillations already occurred during the night of the 6th to 7th, due to the arrival of the first and weaker CME ejected on September 4th. The main effects began after the arrival of the 2nd and strongest CME, ejected from the Sun on September 6th and which reached the Earth on September 7th just after 23 UT. As visible in solar wind and geomagnetic data, the event was separated in 2 main phases : the first one just after the CME arrival, and the second one in the afternoon of September 8th. At the regional scale, strong peaks of scintillations were observed during both phases, but the first peak affected mainly Scandinavia, and was less pronounced at the Mary Arctica, localized at that time between Greenland and Iceland.




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Figure 44 : GPS Scintillations regional mean and onboard Mary Arctica between Sept 6th and 7th

When looking in deeper temporal and spatial detail, it is important to keep in mind that ionospheric scintillation is a very irregular phenomenon: even during general active phases lasting several hours, the activity can evolve in a few minutes from quiet to strong peaks. These peaks are related to the appearance and fast movement of ionization patches inside the auroral regions. These characteristics are particularly true during the end of the event, when the activity can be less related to the solar wind.

The short term spatial evolution for the 3 scintillation peaks observed during the event, depicted in Figure 45, clearly illustrate this behaviour.




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Figure 45 : Scintillation spatial dynamics during 3 peaks of the event : Sept 7th around 23:20 (top), Sept 8th around 00:25 (middle) and around 17:55 (bottom). Patches

propagation are indicated by blue arrows

5.10. Scintillation forecast approach

5.10.1. Forecast method

The solar wind is well documented to be a relevant proxy for geomagnetic activity, and thus high latitudes ionospheric scintillations. This relationship was exploited to build an empirical model of scintillations taking the solar wind as input. Moreover, the solar wind being measured in real time ahead of the Earth, a model based on solar wind has the ability to give a short-time forecast 30 min to 1 hour in advance, depending on the speed of the wind.

The model elaboration relied on 2 long term data sets covering more than 4 years, between July 2011 and September 2015, a large part of solar cycle 24 maximum :

- The ROTI computed between 7 permanent high latitudes stations belonging to EUREF, GNET and IGS networks, located in Scandinavia, Iceland and Greenland




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- The solar wind data measured by the ACE spacecraft, retrieved from ACE Science Center (http://www.srl.caltech.edu/ACE/ASC/)

Figure 46 : GNSS Network used for scintillation model elaboration

The first step was to correlate ROTI with all solar wind parameters. At each station, the ROTI was averaged by 5-min time periods over all visible satellites, and then the time series from all stations were averaged again to give on single time series representing the level of ionospheric activity.

The solar wind was averaged on a 1-hour moving window, with a 5-min step, for all parameters, except Bz were positive values were reduced to 0 prior to the average, considering that the coupling between solar wind and the Earth magnetosphere is efficient only when the interplanetary magnetic field is orientated southward. The most correlated parameters of the solar wind with ROTI were :

- The vertical component of the IMF : Bz - The norm of the IMF : Bt - The speed of the wind

A simple least-square model was computed between all 3 parameters and the ROTI to compute a “Solar Wind Index”, a combination of the solar wind parameters best representing the ionospheric activity.




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Figure 47 : Correlation between ROTI and Bz component of the solar wind

The first step gave a method to have a temporal model of the whole auroral ionospheric activity, so the second step goal was to add a spatial dimension to the model. For that purpose, an external statistical model of the auroral oval was used, adapted from the work of Carbary (2005). This model gives a representation of the auroral optical emissions location and intensity, depending on the Kp geomagnetic index. In order to use this model with the solar wind as input, it was necessary to map our “Solar Wind Index” to the same scale as Kp. It appeared by applying a log transformation and a linear adjustment on 3-hour averages, we find a correlation coefficient of 0.85 between the Solar Wind Index and the Kp.




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Figure 48 : Correlation between Solar Wind Index (combination of IMF and wind speed) with Kp geomagnetic index

At that point, one could obtain for any time and any point in space a level of auroral emission level depending on the solar wind, the last step was then to remap output of the oval model, designed for auroral optical emission, back to ionospheric scintillation, in the scale of the ROTI. Several works have documented the intricate relationship between auroral optical emission and GNSS ionospheric scintillations, such as Kinrade, 2013.

5.10.2. Forecast validation

The method to validate the model was to compute a modelled ROTI value for each single observation, i.e. for each receiver–satellite pair at each time step from July 2011 to September 2015, and then to take the spatial and 5-min temporal average to get a single time series, similar to the observed one. The comparison of both time series confirmed a general good agreement, with a correlation coefficient of 0.73. In particular, the improvement of the correlation compared to the solar wind index only indicates the pertinence of the oval model.




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Figure 49 : Scatter plot of Model ROTI vs Observed ROTI on the whole study period (2011 to 2015)

The model was tested further in detail on the case of March 17th 2015 event, one of the strongest of solar cycle 24, similarly to the campaign event of September 2017. During the whole month of March 2015, one can see that the diurnal variations of scintillations are correctly reproduced, as well as the day to day intensity changes, in particular the much more pronounced activity of the event itself, on the 17th. The spatial behaviour of the event is also quite well taken into account at a regional scale, as illustrated in Figure 51 by the sharp increase of scintillations in the auroral oval just after midday on the 17th.




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Figure 50 : Model ROTI and Observed ROTI in March 2015

Figure 51 : ROTI Map during March 17th 2015 event : observations are yellow to red levels, model is in shades of blue

5.10.3. September 2017 event analysis

The application of the scintillation model to the Sept 2017 event is an interesting test case since it was not part of the data used to build the model. The general behaviour of the event is in good agreement between model and observations, in particular in the start and end phases of the event. The spatial distribution of scintillations is also generally well handled, mainly for the first phase, which is illustrated in Figure 52.




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Figure 52 : ROTI observed (left) and forecast (right) before, during, and after the first phase of 7-8th September 2017 event

However, when comparing forecasted and observed level of ROTI for the Mary Arctica, it appears that during the first phase, the model overestimates somehow the level of activity. The second phase of the event, during the second part of Sept 8th is trickier to forecast since the activity peaks appear to less depend on solar wind variations. Again, the start around 12 TU is correctly modelled but the several subsequent sharp peaks are less well reproduced, which has a smoother behaviour.




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Figure 53 : ROTI observed onboard Mary Arctica and ROTI forecast for the ship during Sept 7-8 2015 event

6. Space Weather forecast warning service prototype

All activities will be described as part of the D6.5 document.




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Appendix A - AIS characteristics

The AIS Automatic Identification System is an automatic tracking system used for collision avoidance. This is an automated message exchange between ships, which allows ships and the traffic surveillance system to know several information about the ship: identity, status, length, course, speed, position, ship's route in the navigation area. The final system will be composed of a Raymarine AIS 650 Class B transceiver.

Although this AIS is a transmitter, it will be used only as a receiver. The AIS requires the use of a VHF antenna (1) and a GPS antenna (2).

Messages frame given by the AIS are NMEA 0183 frame. The data rate is 4800 bauds.

The VHF antenna used is a 6dB fiberglass antenna Glomeasy Glomex :

FREQUENCY RANGE 156/162 MHz GAIN AVERAGE 6dB IMPEDANCE 50 ohms POLARIZATION Vertical SWR ≤ 1,3 at 156,8 MHzMAX INPUT POWER 100 W DC GROUND Yes ANTENNA LENGHT 1,2m' ANTENNA WEIGHT 325g/11,46oz TERMINATION FME




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The GPS antenna is the Raymarine R62241 GPS antenna supplied with the AIS 650:




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Appendix B - GNSS characteristics

The GNSS receiver used for the final system is a C-Nav 3050 receiver. It is compatible with GPS, GLONASS, SBAS (WAAS/EGNOSS) constellation. Moreover, a correction service can be activated to improve position accuracy. Access to the C-Nav Corrections Service (CCS) requires a subscription that must be purchased. Subscriptions are based upon a predetermined period of usage. Subscriptions can be left to expire, or if service is no longer needed prior to the date of expiration of service, a deactivation code can be obtained by contacting C-Nav.

This GNSS receiver requires the use of two antennas, a GNSS antenna and a L-band antenna.

Those two antennas are connected to the C-nav 3050 via a C-Nav combiner:

The technical features of C-Nav 3050 are as follow :




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The C-Nav combiner used is a passive diplexer:




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The GNSS antenna used with the C-Nav 3050 receiver is AT1675-286. Its specifications are:

(in inches)

The L-band antenna is the AD-422 DGPS antenna:




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Appendix C - Argos characteristics

The Argos transmitter is a HAL 2 (High Accuracy Locator) board. This board will be used for transmission.




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The Argos Antenna used is the CXL70-1LW/I. This is a OdBd, vertically polarized, omnidirectional base station and marine antenna which covers the 380-430MHz frequencies.




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Appendix D - Inmarsat characteristics

The Inmarsat transmitter is an IDP690, IsatDataPro.

Size : 12,60 (L) x 12,60 (l) x 10,1 (H) cm;

Weight : 0,46 Kg




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Appendix E - Iridium characteristics

Three different Iridium devices will be installed: A development board containing a 9523 modem, a development board containing a 9602 modem and a Triton beacon.

The development cards will be integrated into the rack-mountable PC.

Modem 9523

The 9523 modem will be used for the remote control of the system. For remotely access the data, and send specific command to the pc.

It will be use in SBD.

Modem 9602

The 9602 Modem will be used to send data in SBD.




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For the two iridium modem, the antenna used is the AeroAntenna AT1621-73W:




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(in inches)




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Triton

TRITON is a VMS, VMS/ERS terminal which is equipped with IRIDIUM modem and Cellular modem. It provides the location measurement data obtained from the built-in GNSS receiver, and execute message transfer such as E-mail, E-Form, etc, between on board Data Terminal Equipment (DTE) and the customer servers.

The dome of the TRITON integrates an Iridium transceiver, a GNSS receiver, a cellular modem:

- Iridium Modem: 9602 Modem

- GNSS Module: SL869

- Cellular Module: GE 910 Quad V3




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Appendix F - Gyroscope characteristics

The gyroscope used is Yost Labs 3-Space™ Sensor USB/RS232.

The YEI 3-Space SensorTM is a miniature, high-precision, high-reliability, Attitude and Heading Reference System (AHRS). The 3-Space family includes sensors with a variety of communication methods, including USB, wireless, serial, and SPI. The Attitude and Heading Reference System (AHRS) uses triaxial gyroscope, accelerometer, and compass sensors.




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Appendix G - UPS characteristics

A UPS (Uninterruptible Power Supply) will be installed as a power supply backup and protection. The UPS is ellipse pro 850 Eaton.




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Appendix H - Acronyms

CME Coronal Mass Ejection

LEO Low Earth Orbit

RF Radio Frequency

SW Space Weather

UPS Uninterruptible Power Supply

Documents

EfficienSea2 - Task 2.6 / D2.6 Report on Space Weather (SW ... · EfficienSea2 -CLS_2 [Nomenclature] V1.0 2017,Oct.27 i. 6 Proprietary information: no part of this document may be