6th Aquarius/SAC-D Science Meeting July 2010 Seattle, Washington, USA MWR Calibration pre-launch & post launch Juan Cruz Gallo (CONAE) Linwood Jones (CFRSL) Daniel Omar Rocca (IAR) Sakay Biswas (CFRSL)

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 2 of 19 July 19-21, 2010 Pre-launch  Receivers calibration using hot/cold loads Calibration and Stability laboratory  End to end calibration on Thermo Vacuum Chamber using absorbers feeds without reflectors Post-launch  Cold Sky Monthly satellite CSC maneuver  Vicarious Calibration  Inter-satellite Calibration MWR Radiometric Calibration Plan

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 3 of 19 July 19-21, 2010 MWR Pre-launch calibration Pre-launch calibration will be performed using two Independent methods: 1)By CONAE-IAR Radiometer transfer function: uses empirical linear regression equation (thermal vac data) Used for level-1 processing (counts to earth scene brightness temp, T ap ) Antenna: Antenna pattern correction 2)By CFRSL Theoretical radiometric transfer function (counts to T ap ) Switch Matrix mathematical model Relates antenna brightness temp (T ant receiver input to earth scene brightness temp (T ap ) collected by feeds Linear receiver transfer function

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 4 of 19 July 19-21, 2010 MWR Pre-launch calibration Receivers calibration using hot/cold laboratory Note: based on ”Calibration of Passive Microwave Polarimeters that Use Hybrid Coupler-Based Correlators”, J. R. Piepmeier IEEE Trans. Geosci. Remote Sensing, Vol. 42, No. 2, February 2004).

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 5 of 19 July 19-21, 2010 Pre-launch calibration Ta Receiver Calibration Raw Data Ca, Cn, Co The components temperature must be controlled  1 ºC and they temperature measured with an accuracy of  0.1 C TFA: Physical Antenna (Horn) Temperature  L: Antenna Radiation Eficiency Quadratic correction are been considered to improve the residual non linearity of the diode detectors

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 6 of 19 July 19-21, 2010 Radiometer Calibration Plan Determination of the  i coeficients  i are estimated by multi-linear regression of data taken when their temperatures were varied in a linearly independent manner, this data is taken during the thermal Vacuum Test. This procedure was used by Topex calibration Team (IEEE:TOPEX Poseidon Microwave Radiometer (TMR): I. Instrument Description and Antenna Temperature Calibration) Where T T denotes the matrix transpose operation. The vector of coefficients,, is estimated from the data by minimum squared error inversion:

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 7 of 19 July 19-21, 2010 Pre-launch calibration

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 8 of 19 July 19-21, 2010 Antenna pattern correction TA: Antenna Apparent Temperature TFA: Physical Antenna (Horn) Temperature  L: Antenna Radiation Efficiency  M: Antenna Main Lobe Efficiency TSL: Side-Lobe Temperature contribution Ulaby-Antenna Pattern Correction Fn( ,  )= Normalized Radiation Pattern Go=Maximum Power Gain Do=Maximum Directivity

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 9 of 19 July 19-21, 2010 Antenna pattern correction

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 10 of 19 July 19-21, 2010 CFRSL Pre-launch calibration Calculate individual feed-horn path losses for both pols Model theoretical radiative transfer based on dissipative losses and leakage coupling Validate model using CONAE thermal vacuum test data Receiver: Non-linearity analysis using noise diode deflection test.

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 11 of 19 July 19-21, 2010 Cold-Space Radiometric Calibration During SAC-D pitch maneuver MWR antenna beams will view cold-space –Cosmic brightness temp T b = 2.73 K –Isotropic and homogeneous Allows radiometric inter-calib between 24 MWR beams –Validation of radiometric transfer function Does not assess antenna pattern affects on calibration

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 12 of 19 July 19-21, 2010 Inter-Sat Radiometric Calibration Normalizes MWR’s T b calibration to other conical scanning radiometer systems –WindSat Polarimetric Radiometer –TRMM Microwave Imager –SSMI –AMSR Leverages off NASA’s microwave radiometer Inter- sat Calib Working Group (X-cal) activities –Uses near-simultaneous and spatially collocated T b observations between a pair of sat radiometers –T b normalization to account for expected freq and geometry differences –homogeneous ocean and land scenes

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 13 of 19 July 19-21, 2010 Near-Simultaneous Match-up Data Sets Match-ups within ±45 minutes & spatial quantization of one degree latitude & longitude Thousands of collocation files generated / day MWR Tb Data WindSat L1C Tb Data GDAS Env. Parameters Match-up Data File Collocated Points

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 14 of 19 July 19-21, 2010 MWR Swath Direction Ascending Swath Direction Flight Direction AQ/SAC-D orbit is lower altitude, therefore AQ travels faster and laps WindSat every ~ 2 days

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 15 of 19 July 19-21, 2010 MWR Swath MWR swath to the right of sat sub-track for ascending track WindSat & Aquarius orbits drift into and out of phase –Orbit Phasing period ~ 30 days to repeat ground track Collocation efficiency > 60% –Worst case temporal collocation ± 45 min (half-orbit period) 380 km 272 km 652 km Swath

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 16 of 19 July 19-21, 2010 Approx 19,000 collocations in 45 hrs (± 50 o Lat) (0.5 o x 0.5 o ) & ± 45 min window Approx 1 Million ocean collocations in 5 months 16 AQ/WindSat Collocations for 45 hrs

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 17 of 19 July 19-21, 2010 Warm Bias (Land) Calibration Targets Example of TMI/WindSat 1°x1° blackbody calibration sites ± 1hr

6th Aquarius/SAC-D Science Meeting Seattle. MWR Calibratio – Jones-Gallo 18 of 19 July 19-21, 2010 Conclusions Pre-launch Calibration will be checked using two methods: CONAE-IAR based on empirical data CFRSL based on radiometer physical model Intercomparison of two independent methods Post-launch calibration Inter-satellite calibration using WindSat CSC Other possibility will be studied e.g. Vicarius calibration