MWR Calibration pre-launch & post launch

Transcription

1 MWR Calibration pre-launc & post launc Juan Cruz Gallo (CONE) Daniel Omar Rocca (IR) inwood Jones (CFRS) Sayak Biswas (CFRS) 9- July Seattle, Wasington, US

2 MWR Radiometric Calibration Plan Pre-launc Receivers calibration using ot/cold loads Calibration and Stability laboratory End to end calibration on ermo Vacuum Camber using absorbers feeds witout reflectors Post-launc Cold Sky Montly satellite CSC maneuver Vicarious Calibration Inter-satellite Calibration of 9 July 9-,

3 MWR Pre-launc calibration Pre-launc calibration will be performed using two Independent metods: ) By CONE-IR Radiometer transfer function: uses empirical linear regression equation (termal vac data) Used for level- processing (counts to eart scene brigtness temp, ap ) ntenna: ntenna pattern correction ) By CFRS eoretical radiometric transfer function (counts to ap ) Switc Matrix matematical model Relates antenna brigtness temp ( ant receiver input to eart scene brigtness temp ( ap ) collected by feeds inear receiver transfer function 3 of 9 July 9-,

4 4 of 9 July 9-, MWR Pre-launc calibration Receivers calibration using ot/cold laboratory Note: based on Calibration of Passive Microwave Polarimeters tat Use Hybrid Coupler-Based Correlators, J R Piepmeier IEEE rans Geosci Remote Sensing, Vol 4, No, February 4) Offset matrix temperature matrix Brigtness Gain matrix output matrix Voltage at detector : : G : V : o V V V V U U U m p v v m m mv p p pv vv m p v o o o o G G G G G G G G

5 Pre-launc calibration a Receiver Calibration Raw Data Ca, Cn, Co C D C o n C C a a V V o n V V a a ( OR NR R R ) ' ( - ) F F: Pysical ntenna (Horn) emperature : ntenna Radiation Eficiency e components temperature must be controlled ºC and tey temperature measured wit an accuracy of C a (F C F C ) O ( )(FC F C ) F ( FC ) F C D a F C F D a F C N ON D F 3 F 4 F D 5 Quadratic correction are been considered to improve te residual non linearity of te diode detectors N 5 of 9 July 9-,

6 6 of 9 July 9-, Radiometer Calibration Plan Determination of te i coeficients 5 N N N C C C D D D F D F F F D F F D F F F i are estimated by multi-linear regression of data taken wen teir temperatures were varied in a linearly independent manner, tis data is taken during te termal Vacuum est is procedure was used by opex calibration eam (IEEE:OPEX Poseidon Microwave Radiometer (MR): I Instrument Description and ntenna emperature Calibration) C C Were denotes te matrix transpose operation e vector of coefficients,, is estimated from te data by minimum squared error inversion: N D D F F F 5 4 3

7 Pre-launc calibration 7 of 9 July 9-,

8 ntenna pattern correction Ulaby-ntenna Pattern Correction M M ' - - M M S - - M F ' ( - ) F : ntenna pparent emperature F: Pysical ntenna (Horn) emperature : ntenna Radiation Efficiency M: ntenna Main obe Efficiency S: Side-obe emperature contribution S Main 4 π - obe Main 4 π - obe P ( θ, ) F F n ( θ, ) n ( θ, ) dω dω M Go Do Main obe 4π 4π F F n ( θ, ) n ( θ, ) 4Go F n ( θ, ) dω dω dω Fn(,)= Normalized Radiation Pattern Go=Maximum Power Gain Do=Maximum Directivity 8 of 9 July 9-,

9 ntenna pattern correction 9 of 9 July 9-,

10 CFRS Pre-launc calibration Calculate individual feed-orn pat losses for bot pols Model teoretical radiative transfer based on dissipative losses and leakage coupling Validate model using CONE termal vacuum test data Receiver: Non-linearity analysis using noise diode deflection test of 9 July 9-,

11 Cold-Space Radiometric Calibration During SC-D pitc maneuver MWR antenna beams will view cold-space Cosmic brigtness temp b = 73 K Isotropic and omogeneous llows radiometric inter-calib between 4 MWR beams Validation of radiometric transfer function Does not assess antenna pattern affects on calibration of 9 July 9-,

12 Inter-Sat Radiometric Calibration Normalizes MWR s b calibration to oter conical scanning radiometer systems WindSat Polarimetric Radiometer RMM Microwave Imager SSMI MSR everages off NS s microwave radiometer Intersat Calib Working Group (X-cal) activities Uses near-simultaneous and spatially collocated b observations between a pair of sat radiometers b normalization to account for expected freq and geometry differences omogeneous ocean and land scenes of 9 July 9-,

13 Near-Simultaneous Matc-up Data Sets GDS Env Parameters MWR b Data Matc-up Data File Collocated Points WindSat C b Data Matc-ups witin ±45 minutes & spatial quantization of one degree latitude & longitude ousands of collocation files generated / day 3 of 9 July 9-,

14 MWR Swat Direction scending Q/SC-D orbit is lower altitude, terefore Q travels faster and laps WindSat every ~ days Fligt Direction Swat Direction 4 of 9 July 9-,

15 MWR Swat MWR swat to te rigt of sat sub-track for ascending track WindSat & quarius orbits drift into and out of pase Orbit Pasing period ~ 3 days to repeat ground track Collocation efficiency > 6% Worst case temporal collocation ± 45 min (alf-orbit period) 65 km 7 km 38 km Swat 5 of 9 July 9-,

16 Q/WindSat Collocations for 45 rs pprox 9, collocations in 45 rs (± 5 o at) (5 o x 5 o ) & ± 45 min window pprox Million ocean collocations in 5 monts 6 of 9 July 9-, 6

17 Warm Bias (and) Calibration argets Example of MI/WindSat x blackbody calibration sites ± r 7 of 9 July 9-,

18 Conclusions Pre-launc Calibration will be cecked using two metods: CONE-IR based on empirical data CFRS based on radiometer pysical model Intercomparison of two independent metods Post-launc calibration Inter-satellite calibration using WindSat CSC Oter possibility will be studied eg Vicarius calibration 8 of 9 July 9-,