armasuisseSwiss Federal Office of Topography swisstopo
swisstopo Report for EGVAP 2008/2009
E. Brockmann
2 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Content
• Routine GNSS operation: - Status report: Processing, availability- Comparison with radio sondes- Study of the influence of snow
• Tomography approach (project MeteoSwiss, ETH Zurich with ZTD data + double-difference data from swisstopo; results prepared by D. Perler, ETH Zurich)
3 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
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Processing remarks
• Bernese Software 5.0 (+) – close cooperation with University of Berne
• Same strategy since November 2006 (GPS week 1400)• Number of sites (and satellites) slightly increased – not yet
analyzed 6 super stations included Nov. 12, 2008
~90 sites32 + 15 sat.
~90 sites
4 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
GNSS processing
• Since Nov. 06: GPS+GLONASS combined processing• Mid 2007: Permanent network in Switzerland enhanced
(GPS-GLONASS combined receivers installed)• Since Oct. 07: ambiguity resolution for hourly processing
• [March 2008: absolute antenna model, 3 degrees elevation cut-off, gradient estimation, GNSS as input for tomography]
• Today (Nov. 09): 32 GPS and 15 GLONASS satellites – March, 2009 the magic number of 51 GNSS was reached
Baseline length strategy Fixed Ambiguities
0 - 20 km L1/L2 95 - 100%
20 - 200 km L5/L3 90 - 100%
200 - 2000 km QIF *) 70 – 80%
5 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Processing remarks (2)
• rms of unit weight estimated for the GPS phase observables: higher during summer times – evtl. Meteo more difficult to model (?)
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6 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
EUMETNET – EUREF – MOU: swisstopo use• signed in London, June 2007:
Data exchange and usage of radiosonde and synop (meteo) for geodetic scientific use
• Routinely 13 collocations with radio sonde data analyzed at swisstopo
GNSS site
RS site
7 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
GNSS validation: PAYEReference: PP, GNSS, absolute antenna PCV
GLONASS influence is small for daily PP amb-fix solutions
Relative antenna model causes bias
RRT solution with bigger variations (small network)
8 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Validation using different processing options and external sources
Radio sonde comparison of 13 sites: ~ positve bias last weeks
9 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Validation with radio sonde data: PAYE• reference: GNSS postprocessing• Absolute antenna phase center related since Mid 2007
Trimble Cephyr antenna• Seasonal variations clearly visible
10 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Radio sonde – GPS: PAYE (D. Perler)
• Relative antenna phase center till March 2008• Antenna change (GPS -> GLONASS): June 2007
Trimble Microcentered TRM33429.20+GP -> Cephyr antenna TRM55971.00 ( )
• Jump + seasonal variations + day/night differences substracted
11 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Radio sonde – GPS: PAYE (D. Perler)
• Results from 2 years: 0:00, 12:00 UTC measurements• Mean ZTD with seasonal variations substracted
• At noon: ZTD of radio sonde is 6 mm smaller as GPS
Radio sonde GPS
day: 12:00 UTC 2.2832 ± 0.0011 m 2.2893 ± 0.0012 m
night: 0:00 UTC 2.2945 ± 0.0011 m 2.2929 ± 0.0012 m
night - day difference
0.0114 ± 0.0015 m 0.0036 ± 0.0017 m
???
?
12 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Validation with radio sonde data: PAYE • reference: Real-time monitoring• All plots available on http://www.swisstopo.ch/pnac – similar
monitoring system as EGVAP with traffic light symbols• Radio sonde data with a time delay available
13 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Availability
• Meteo processing and coordinate monitoring closely related• Availability is important: 99.66% LPT_; 96.49% LPTR
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14 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Example heavy snow fall: PAYE
December 2008 - Status
PAYE
15 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Example heavy snow fall: PAYE (2)
December 2008 – coordinates 20 cm off (height) !
1 point = 1 hour1 point = 1
hour1 point = 30 Seconds (kinem.)
Positioning service monitor
16 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Example heavy snow fall: PAYE (3)
December 2008 - ZTDs
• ZTD parameters are highly biased in case of heavy snow falls – as also the corresponding coordinates…
17 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Example heavy snow fall: PAYE (4)
December 2008 – ZTDs eliminated in postprocessing
18 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Example heavy snow fall: PAYE (5)
• Antennas are quite sensitive to surrounding – replacement of 6 antennas in May 2009 with chokering antennas (after extensive snow tests in the Alps); further antenna replacements planned.
Case 2, January 2009 – picture of the antenna – only a small bias in the coordinates (3 cm in height)
19 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Tomography
• GANUWE Project- Swiss project funded by the Swiss Federal Office of the
Environment FOEN- Partners: ETH Zurich + MetoSwiss- External partner: swisstopo
• Goal: Make tomography usable in numerical weather prediction
• Follow up project of phD (Kruse, Troller) and “local networks” (Lutz)
• Results prepared by D. Perler (ETHZ)
20 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Improvements
• Data- GLONASS supported- ZTD estimates based on
absolute phase center variations
- More GNSS stations• Computational
- Kalman filter implementation (instead collocation)
- Voxel parametrization (constant, multi-linear, spline)
- Simulator (point measurements, ZTD, Slant-delay, Double-differences)
Simulation of more satellite systems:gain for GNSS tomography
21 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
GNSS tomography: data flow
GNSS-double-differences
GNSS-ZTD
Surface meteo
Radio sondes
measurements
Tomographysoftware
AWATOS 2Weather model
Spectrometer
MeteoSwiss
swisstopo
MeteoSwiss
22 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Results with real Data from the GPS Network
• Comparison between tomographic solutions and radio sounding observations
• Non-constant parameterized solutions have smaller standard deviation than the constant parameterized ones.
• Spline/bilinear solution at noon oscillates above 6km.
23 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
Results with data from the GPS network
video
• Outlook:
project with dense network (2-3 km resolution) and low-cost L1 receiver planned
24 Swiss Federal Office of Topography swisstopo
swisstopo Report 2009 for EGVAP
“Climatology” for Geodesists
downward movementrise
1 mm/yrDerived from10 years GPS analysis
Thank you for your attention