Cloudnet Observing Stations Instrumentation C L Wrench Cloudnet Final Symposium – 12 October 2005

Cloudnet Observing Stations

Instrumentation

C L Wrench

Cloudnet Final Symposium – 12 October 2005

Cloud Remote Sensing Stations


Cloudnet started with three cloudobserving stations:

(1) Cabauw, The Netherlands[51.971N, 4.927E]

(2) Chilbolton, United Kingdom[51.145N, 1.437W]

(3) SIRTA-Palaiseau, France[48.713N, 2.204E]

Each CRS station had been developed over a number of years prior to 2001 with national funding.

The instrumentation available at each site was different.

CRS - CABAUW


View from the 213m tower towards the remote sensing site

Cabauw is operated by KNMI; it is located in the western part of the Netherlands and it is0.7m below sea-level. Surface elevation changes by no more than a few metres over 20km. The surrounding region is mainly agricultural.

Measurements made using the following remote sensing systems at Cabauw have contributed to Cloudnet:

• 35 GHz cloud radar (KNMI)

• 3.3 GHz FMCW radar (TARA) (TUD) • 905 nm lidar ceilometer (CT75K) (KNMI)

• 22 channel wave radiometer (MICCY) (UBonn)

• Total Sky Imager (TSI-440) (KNMI)

Additional observations made within 100km of Cabauw with:

• Ceilometers (CT12K, LD-40)• Sky infrared temperature

Cesar

CRS - CHILBOLTON


View of the cloud radars and lidars with the 25m antenna behind

Chilbolton is operated by CCLRC-RAL; it is located in Southern England and itis 84m above sea-level.Surface elevation changes by 240m over20km. The surrounding region is mainly agricultural downland with some wooded and residential areas.

Measurements made using the followingremote sensing systems at Chilbolton have contributed to Cloudnet:

• 35 GHz cloud radar (Copernicus)• 94 GHz cloud radar (Galileo)• 905 nm lidar ceilometer (CT75K)• 3 channel wave radiometer

Additional observations made atChilbolton with:

• 355 nm Raman lidar• 3 GHz radar (CAMRa)• Visible sky camera

CF A RR

CRS - SIRTA


SIRTA remote sensing site at Palaiseau

Palaiseau is operated by IPSL; it islocated in a suburban community on a plateau 20km south of Paris, and it is ~160m above sea-level. The plateau is semi-urban divided equally between agricultural fields, wooded and housing/industrial areas

Measurements made using the following remote sensing systems at SIRTA have contributed to Cloudnet:

• 95 GHz cloud radar (RASTA)• 1064/532 nm polarimetric lidar• Ceilometer (LD-40)• 2 channel wave radiometer

(DRAKKAR)

Additional observations made atSIRTA with:

• Surface flux station (pyrheliometer/ pyranometer/pyrgeometer)• Sun-photometer• Radiosonde launches• Sonic anemometers (10 + 30 m)

Data from additional CRS-stations


Distribution of DOE-ARM sites providing data to Cloudnet

Cloudnet processing algorithmshave been applied to data sets collected at additional sites.

These include: DWD-Lindenberg (Germany) ARM-SGP (Oklahoma) ARM-TWP (Manus) ARM-TWP (Nauru) ARM-NSA (Barrow)

All of the additional sites contain a 35 GHz cloud radar, a ceilometer and a multi-frequency microwave radiometer.

Cloudnet achievements


Meeting objectives set at the beginning of the Cloudnet project:

• Operate the stations for a minimum of one week per month for two years

Achievements:• Operations at all sites started in October 2002 • Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:

Cloud radars / Backscatter lidars / Microwave radiometers

Radar Data for Cloudnet


Instrument [Location]

Type Range Resolution

Type of operation

Data collected

34.86 GHz

[Cabauw]

Coded-Pulse

Doppler

Co-Pol +’X-Pol’

0.2 – 13 km

adjustable

90 m

adjustableContinuous 8/2001 - 6/2005

TARA

3.3 GHz

[Cabauw]

FM-CW

Doppler

Dual-Pol

15 km 30 mContinuous 10/2001 -

9/2005

GALILEO

94.0 GHz

[Chilbolton]

Pulsed

Doppler

Co-Pol

16 km 60 mContinuous

8/2001 - 3/2002

4/2003 - 4/2004

COPERNICUS

34.96 GHz

[Chilbolton]

Coded-Pulse

Doppler

Dual-Pol

15 km

adjustable

30 m

adjustableContinuous

4/2004 - 10/2004

12/2004 - 9/2005

RASTA

95.0 GHz

[SIRTA]

Pulsed

Doppler

Co-Pol

15 km 60 m Mon-Fri

(8:00-20:00)

------------

Continuous

10/2002-9/2003

-------------------

10/2003-9/2004

Lidar data for Cloudnet


Instrument

[Location]

Type Range Resolution

Type of

operation

Data collected

CT75K 905 nm

[Cabauw]Ceilometer

11 km 30 m Continuous9/2001-9/2005

CT75K

905 nm

[Chilbolton]

Ceilometer11 km 30 m Continuous

9/2001-9/2005

LNA

1064/532 nm

[SIRTA]

Pulsed

Co-Pol+X-Pol

15 km 15 m Mon – Fri

(8:00 – 20:00)

[Not in rain]

10/2002-9/2005

LD-40

[SIRTA]Ceilometer

6 km 30 Continuous01/2003-10/2004

wave radiometer data for Cloudnet


Instrument

[Location]

Channel Frequencies

Channel BTmp resolution

Type of operation

Data

collected

MICCY

[Cabauw]

[22 channels]22.235 - 28.235 GHz

50.8 - 58.8 GHz

90.0 GHz~0.1 K

Continuous 8/2001 – 8/2003

CMR

[Chilbolton]

22.2 GHz

28.8 GHz

37.6 Ghz

0.4 K Continuous 4/2003 - 9/2005

DRAKKAR

[SIRTA]

23.5 GHz

36.5 GHz 0.25 K Continuous 7/2002 - 9/2005





Achievements:• Operations started in October 2002 – see data summary tables• Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:

Cloud radars / Backscatter lidars / Microwave radiometers

• Successful cross-calibration of the three cloud radars was achieved by RASTA being operated at Chilbolton and Cabauw





Achievements:• Operations started in October 2002 – see data summary tables• Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:

Cloud radars / Backscatter lidars / Microwave radiometers• Successful cross-calibration of the three cloud radars was achieved

by RASTA being operated at Chilbolton and Cabauw

• Investigated the lifetime and reliability of the cloud radar amplifiers

Experiences with 94 GHz Cloud Radar amplifiers


The Extended Interaction Klystron Amplifier (EIKA) in the 94 GHz GALILEO radar at Chilbolton operated for 3 years losing 20dB of Tx power before it failed in March 2002.

Plot of Z measured using GALILEO in rain illustrates how the power declined with time

A replacement EIKA for GALILEO was acquired in April 2003 – it ran for 12 months continuously before it lost 10dBof Tx power. This is in line with similarlosses experienced by the EIKA in RASTA

Design modifications to the cathode and its operating temperature are being implemented by the manufacturer

Experiences with 35 GHz Cloud Radar amplifiers


The output power of the 35 GHz travelling wave tube (TWT) that is used in the cloud radar at Cabauw has gradually decreased with time. In August 2001 the output power was approximately 90 W, it had decreased to 20 W by the end of 2004. This was more than expected for a TWT operated continuously for 4 years.

The output power from the 35GHz EIKA used in theCOPERNICUS radar at Chilbolton has remained high after 22 months of operation. There has been a 1.5dB fall in gain after 16,000 hours. Can cope withanother ~12dB loss in gain





Achievements:• Operations started in October 2002• Successfully demonstrated an ability to make long term unattended observations with three key remote sensing instruments:

Cloud radars / Backscatter lidars / Microwave radiometers• Successful cross-calibration of the three cloud radars was achieved

by RASTA being operated at Chilbolton and Cabauw• Investigated the lifetime and reliability of the 94GHz radar amplifier

• Development of new techniques for auto-calibration of cloud radarsand cloud lidars – subject of next talk (Ewan O’Connor)

Cloudnet achievements (cont)


• Archived the model forecast data over each of the sites• Data from seven operational forecast models were archived at the University of Reading for each of the CRS stations

• Measurements – data handling• Processed data collected during the project has been archived at the University of Reading

• Objective categorisation of radar and lidar targets – subject of later talk (Robin

Hogan)

• Development of a technique to improve estimation of LWP from wave radiometers by use of ceilometer data

Documents

Cloudnet Observing Stations Instrumentation C L Wrench Cloudnet Final Symposium – 12 October 2005