IWF/ÖAW GRAZ Jason-2 Altimeter Calibration Status Quo Walter Hausleitner, Jörg Weingrill Altimeter Calibration Workshop 2010 Graz, Austria
Jan 13, 2016
IWF/ÖAW GRAZ
Jason-2 Altimeter Calibration
Status Quo
Walter Hausleitner, Jörg Weingrill
Altimeter Calibration Workshop 2010
Graz, Austria
IWF/ÖAW GRAZ
Transponder Experiments
Transponder site on Gavdos, Greece
Jason-2 calibration –present statusproblems
IWF/ÖAW GRAZ
Transponder site
IWF/ÖAW GRAZ
Transponder instrument
Frequency / Bandwidth Centre Frequ. 13.7 GHz
Bandwidth: 600 MHz
Total gain: 77 dB
Intrument delay: 13.25 ns
IWF/ÖAW GRAZ
Ocean vs. point target response
IWF/ÖAW GRAZ
Point target response
IWF/ÖAW GRAZ
Calibration data availability 2009
Pass Cal Status Data
Date Cycle OK / fail S-IGDR SIMPACALCal. range
comm. Aux. Data
09 09 12 44 OK YES YES
09 09 22 45 fail YES YES
09 10 01 46 fail YES YES
09 10 11 47 OK YES YES
09 10 21 48 no CAL
09 10 31 49 OK YES
09 11 10 50 OK YES YES YES
09 11 20 51 fail YES
09 11 30 52 no CAL YES
09 12 10 53 no CAL YES
09 12 20 54 no CAL YES
09 12 30 55 no CAL YES YES
09 01 09 56 no CAL YES YES
09 01 19 57 no CAL YES YES
IWF/ÖAW GRAZ
Calibration data availability 2010
Pass Cal Status Data
Date Cycle OK / fail S-IGDR SIMPACAL
CalibrationRange
command Aux. Data
10 01 28 58 fail YES YES
10 02 08 59 no CAL YES YES
10 02 17 60 fail YES YES
10 02 27 61 no CAL YES YES
10 03 09 62 OK YES YES YES
10 03 19 63 fail YES YES
10 03 29 64 OK YES YES YES
10 04 08 65 fail YES YES
10 04 18 66 fail YES YES
10 04 28 67 no CAL YES
10 05 08 68 OK YES YES
10 05 17 69 fail YES
10 05 27 70 OK YES YES
10 06 06 71 OK YES
10 06 16 72 fail YES
IWF/ÖAW GRAZ
Data processing concept
Reproduce obs. corr.
Combine S-IGDR+Calibr.
Interp. TRP meas. corr.
Geometric Corr.
Precise range residual
Geophysical Corr.Atmospheric Corr.
S-IGDR data extraction
Calibration DataS-IGDR
Compute absolute times
Fit parabola to echo bins
IWF/ÖAW GRAZ
S-IGDR
Sensor Interim Geophysical Data Records (S-IGDRR)
NetCDF Files from podaac.jpl.nasa.gov1 Hz data + 20 Hz high-rate data
Waveforms
Latency: 2 days
Pass 018Descending Gavdos pass
Pass 018
IWF/ÖAW GRAZ
S-IGDR
S-IGDRRm data records used lat lat_20hz lon lon_20hz range_ku range_20hz_ku rad_wet_tropo_corr model_dry_tropo_corr iono_corr_alt_ku sea_state_bias_ku model_wet_tropo_corr
alt alt_20hz mean_sea_surface solid_earth_tide pole_tide inv_bar_corr hf_fluctuations_corr net_instr_corr_range_ku
IWF/ÖAW GRAZ
Jason-2 Calibration
S-IGDR error budget
From Jason-2 Products Handbook
IWF/ÖAW GRAZ
Calibration analysis concept
11 sec data gap
3 sec calibrationwaveforms
Computation of closest approach time from S-IGDR orbit
Identification of TRP echo bin for each elementary waveform
Parabola fit and determination of vertex
Tie vertex of parabola to closest orbit point for aligning the calibrations to the orbit
Derive absolute times for each TRP echo bin through the relative times given calibration interval and bin-size
IWF/ÖAW GRAZ
S-IGDR data interpolation
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Poseidon-2 elementary calibration
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TRP echo bin detection
Lagrange interpolation of TRP power response
Numerical differentiation and Gaussian curve fitting
Power dependent weighting for each bin
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Closest approach time/distance
Parabola fitting through TRP echo bins
Determination of fractional calibration number at parabola vertex
Aligning vertex with absolute time of closest approach
IWF/ÖAW GRAZ
Altimeter range commandDate 2009/11/10
Time 14:19:34
Date Exec. CAL2
Only known to integerseconds ?
Ho 4604232
LSB Ho .0073191518 m
NSPEC 3
NCAL 32
3.125 nsNS
PE
C *
0.0
5100
769
IWF/ÖAW GRAZ
Ambiguity of cal range
Altimeter range command 34 km
Ambiguity = (18/PRF)*c/2 PRF = 2058.513239 Hz
1310 km
Ambiguity + Calibration range 1344 km
IWF/ÖAW GRAZ
Altitude vs. Ku-band range
IWF/ÖAW GRAZ
Propagation and reflection effects
Source Uncorr. effect
Cycle 50Corr.
Wet
Troposph
0-30 cm 15 cm
Dry troposphere
230 cm 229.5 cm
Iono troposphere
0.2-20 cm 1.6 cm
Sea state bias
0-20 cm 8.8 cm
IWF/ÖAW GRAZ
Corrected range
m
IWF/ÖAW GRAZ
Sea surface height
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Geophysical corrections
Mean sea surface
Solid Earth tide
Geocentr. Ocean tide
Pole tide height
Inv. barom. height eff.
HF fluctuations of SST
IWF/ÖAW GRAZ
Geophysical corrections (cont’d)
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Interpolation effects
There is a significant difference between either
interpolating the individual corrections and sum up the interpolated corrections
Summing up the corrections and interpolate the sum of corrections
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Signal runtime corrections
r
Geoid
Ellipsoid
hS
Center of mass correctionAltimeter instrument delay
hT
href
SST
GPS Transponder/Altimetry
Dry troposphereWet troposphereIonosphere
Transponder delayOffset station markerSlant range correction
Solid Earth tidesPole tides
IWF/ÖAW GRAZ
TRP range residuals
r
Geoid
Ellipsoid
Calibration bin rangeAmbiguityAltimeter delayCoM CorrectionDry troposphereWet (water vapour)Ionosphere
TRP delay (electronic)TRP delay (geometric)Station marker eccentricitySlant range correction
TRP ell.heightSolid earth tides
Corrections
Effect Magnitude (m)
Orbital heightResidual
33738.0881310718.858 -5.173 0.471
- 3.972 -1.477 -0.824
251.169 -0.060
1344398.967 44.575
-2.297-0.116-0.016