Hobart Australia March 2007 Willy Bertiger Ocean Surface Topography Science Team Meeting GPS-Based Precise Orbit Determination: Jason-1 Status Willy Bertiger, Bruce Haines, Shailen Desai Jet Propulsion Laboratory, California Inst. of Tech., Pasadena CA Pascal Willis Institut Geographique National/Institut de Physique du Globe de Paris, France March, 2007 Ocean Surface Topography Science Team Meeting Hobart, Australia
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Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting GPS-Based Precise Orbit Determination: Jason-1 Status Willy Bertiger,
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Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
GPS-Based Precise Orbit Determination: Jason-1 Status
Willy Bertiger, Bruce Haines, Shailen DesaiJet Propulsion Laboratory, California Inst. of Tech., Pasadena CA
Pascal WillisInstitut Geographique National/Institut de Physique du Globe de
Paris, France
March, 2007
Ocean Surface Topography Science Team Meeting
Hobart, Australia
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
• Better Understanding of GPS Phase Centers based on GRACE Dynamics and Calibrations
• JEM03 – GRACE Static Gravity Field (vs GGM02C)
– AOD1B Release 4 ( vs none )
• Sub-daily density variations in atmosphere, gravitational effect
• ITRF2005 (vs ITRF2000)
Release 07a Incremetal Changes Relative to Release 06b (March 2006)
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
GRACE As An Antenna Instrument For GPS Trans. Calibration
• Daily precise orbit solutions spanning two years (2004–06)
• One s/c at a time• Dynamical POD to preserve link
between scale and GM
– CD and 1 cpr acc. reset every rev. per UT/CSR approach
• GPS ephemeris and clock offsets fixed to precise values (JPL/IGSAC)
• GRACE antenna a priori PCV model from anechoic chamber:
• 30-sec GPS data– Carrier (LC) only and carrier + code (LC +
PC) solutions performed. No Z apriori• Postfit residuals binned according to az/el of
transmitters.– Least-squares fit to antenna map– Iterate until converged (12XLC, 5XLC/PC)
–15
0
15mm
0
December 11, 2006 BJH 4Fall AGU 2006
mm
-10
+10
GRACE-Based Phase-Center Variation (PCV)
Maps Reveal GPS Antenna Elements
-12
+18
mm
Block II/IIA PCV
Block IIR-B(M) PCV
-10
+10
mm
Block IIA Antenna(Mader and Czopek, 2002)
Block IIR-A PCV
PCV for Ionosphere-free Carrier (LC) with Mean Offset Removed
December 11, 2006 BJH 5Fall AGU 2006
T/P Radial Antenna Offset Explained
-100
-50
0
50
100
-12
-8
-4
0
4
8
12
1994.0 1996.0 1998.0 2000.0 2002.0 2004.0 2006.0
Time Series of T/P and Jason-1 Radial Antenna Offset EstimatesNoneIGSJPLBCDBCD
Nominal (Gipsy) ModelGRACE-Based GPS PCV Maps
mm
ppb
Year
TOPEX/Poseidon Jason-1
GRACE Data SpanUsed In
PCV Maps
D
-8.2953701Minimum
8.5058155Maximum
0.60300648Sum
19Points
0.031737183Mean
1.1129774Median
4.6419038RMS
4.7689914Std Deviation
22.743279Variance
1.0940817Std Error
-0.039184551Skewness
-0.92282638Kurtosis
Slope = +3.7 ± 0.1 mm/yr
Slope = +0.1 ± 0.1 mm/yr
Bias = +55.6 ± 0.8 mm
B
48.259182Minimum
60.715157Maximum
1056.7383Sum
19Points
55.617803Mean
55.645386Median
55.716286RMS
3.4020173Std Deviation
11.573722Variance
0.78047629Std Error
-0.39930782Skewness
-0.57790671Kurtosis
Bias = +0.0 ± 1.1 mm
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
JASON Calibration (3 Iterations)
• Dynamic JASON runs 2002-JAN-14 to 2006-JAN-01• Very similar in appearance to release 06b (last year)
Phase Code
-400 400-30 30
mm mm
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Release 07a Comparison with GDRB
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
GDRB-ITRF2000, Rel07a/GSFC-ITRF2005
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Reference Frame, Differences with GSFC SLR/DORIS
Model Errors, GPS?Some Pattern with GDRB
-15
-10
-5
0
5
10
15
20 -100
-50
0
50
1000 50 100 150
X MeanY MeanZ Mean
BetaM
ea
n D
iffe
ren
ce
(m
m)
Be
ta (d
eg
ree
s)
Cycle
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Geographic Radial Comparison to GDR-B
-16 160
mmmm
Cycles 21-39 Cycles 150-169
RMS: 1.9 mm RMS: 3.5 mm
-16 160
ITRF2000 - 05 Z ~ 11.5ITRF2000 - 05 Z ~ 5.1
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Geographic Radial Comparison to GSFC SLR+DORIS
-16 160
mmmm
Cycles 21-39 Cycles 150-169
RMS: 2.9 mm RMS: 3.4 mm
-16 160
GSFC and JPL Rel07a both use ITRF2005
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Release 06b - Release 07a
mm
Cycles 141-146
RMS: 1.8 mm
-16 160
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Xover Tests
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting
Xover Tests
Hobart Australia March 2007Willy Bertiger Ocean Surface Topography Science Team Meeting