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 status problems

IWF/ÖAW GRAZ Transponder site

IWF/ÖAW GRAZ Transponder instrument  Frequency / Bandwidth  Centre Frequ 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 PassCal StatusData DateCycleOK / failS-IGDRSIMPACAL Cal. range comm.Aux. Data OK YES failYES failYES OK YES no CAL OK YES OKYES failYES no CALYES no CALYES no CALYES no CALYES no CALYES no CALYES

IWF/ÖAW GRAZ Calibration data availability 2010 PassCal StatusData DateCycleOK / failS-IGDRSIMPACAL Calibration Range commandAux. Data failYES no CALYES failYES no CALYES OKYES failYES OKYES failYES failYES no CALYES OKYES failYES OKYES OKYES failYES

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.gov  1 Hz data + 20 Hz high-rate data  Waveforms  Latency: 2 days  Pass 018  Descending 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 calibration waveforms  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

IWF/ÖAW GRAZ Poseidon-2 elementary calibration

IWF/ÖAW GRAZ TRP echo bin detection  Lagrange interpolation of TRP power response  Numerical differentiation and Gaussian curve fitting  Power dependent weighting for each bin

IWF/ÖAW GRAZ 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 command Date2009/11/10 Time14:19:34 Date Exec. CAL2Only known to integer seconds ? Ho LSB Ho m NSPEC3 NCAL ns NSPEC *

IWF/ÖAW GRAZ Ambiguity of cal range  Altimeter range command  34 km  Ambiguity = (18/PRF)*c/2  PRF = 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 50 Corr. Wet Troposph 0-30 cm15 cm Dry troposphere 230 cm229.5 cm Iono troposphere cm1.6 cm Sea state bias 0-20 cm8.8 cm

IWF/ÖAW GRAZ Corrected range    m

IWF/ÖAW GRAZ Sea surface height

IWF/ÖAW GRAZ 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)

IWF/ÖAW GRAZ 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

IWF/ÖAW GRAZ Signal runtime corrections r Geoid Ellipsoid hShS Center of mass correction Altimeter instrument delay hThT h ref SST GPS Transponder/Altimetry Dry troposphere Wet troposphere Ionosphere Transponder delay Offset station marker Slant range correction Solid Earth tides Pole tides

IWF/ÖAW GRAZ TRP range residuals r Geoid Ellipsoid Calibration bin range Ambiguity Altimeter delay CoM Correction Dry troposphere Wet (water vapour) Ionosphere TRP delay (electronic) TRP delay (geometric) Station marker eccentricity Slant range correction TRP ell.height Solid earth tides Corrections EffectMagnitude (m) Orbital height Residual