Meteorological Satellite Center Japan Meteorological Agency Visible channel vicarious calibration methodology and recent progress at JMA Meteorological Satellite Center Japan Meteorological Agency Prepared for GSICS Tele-conference, 08 Dec. 2009

Vicarious calibration and GEO-MODIS approach Pros and cons ISCCP Absolute coefficients (Slope)

Calibration Methodology Vicarious calibration Rebuild visible calibration table, Based on comparison of observation with simulation. Radiative transfer calculation To make simulation accurately, RT calculation is done on temporally and spatially stable area = Reference target The reference target should be over wide range of brightness to obtain reliable regression line. Cloud-free ocean : Dark site Cloud-free land : Medium brightness site Uniform liquid Cloud Top : Bright site RT calculation requires some inputs depending on each type of the reference site. Stripe noise removal Sensitivity difference between detectors are estimated. Regression line Simulation Offset 3 Observation 3

Necessary data set and tools Input factors to RT calculation: Sun and satellite location Atmospheric profile WV, Pressure, Temperature (JRA-25 or JCDAS) Ozone (TOMS) Scattering particle (depends on target type) Aerosol or Cloud (retrieval from MODIS L1B) Surface condition (depends on target type) Land surface reflectivity (MODIS BRDF MOD43) or Sea surface wind speed (JRA-25 or JCDAS) Tools: RT calculation code (RSTAR) Aerosol retrieval tool (REAP) Cloud property retrieval tool (CAPCOM) Cf. http://www.ccsr.u-tokyo.ac.jp/~clastr/ Aerosol Cloud-free ocean Cloud-free land Aerosol Cloud Liquid cloud top 4

Consistency check of the approach The radiance simulation approach is evaluated by using MODIS data. MODIS carries onboard calibrators for visible bands and it is well-calibrated. Its observations are reliable. Computation and observation show good consistency RMSE is around 1% MODIS Radiance comparison Liquid Cloud MODIS L1B Aerosol Cloud Sim. Radiance retrieve RT calc compare Atmos. prof. Simulated radiance Cloud-free Land Cloud-free Sea 5 MODIS L1B (Band-1) 5

Results GMS-5 MTSAT-1R Calibration between 2000–2003 is completed The calibration coefficients are stable MTSAT-1R The approach is also confirmed for MTSAT-1R Processing of past data can be started soon GMS-5 Reflectivity Observation Computation MTSAT-1R Reflectivity Observation Computation Trend of the slope

JMA’s sunphotometer site Validation method Comparison of retrieved product with ground observation or other satellites’ product Retrieved cloud optical thickness vs MODIS prod. Retrieved aerosol opt. thickness vs Ground obs. Retrieved downward solar flux vs Ground obs. Example : Aerosol optical thickness (AOT) Underestimated AOT is improved JMA’s sunphotometer site RMSE of AOT Original Recalibrate

Recent progress Test to apply the approach for other GEO satellites is in progress under a joint research with Chiba Univ. Deep Convective Cloud is under investigation as a brightest target Trial case MTSAT-2 GOES-10 GOES-8 MTSAT-1R Observation Computation DCC

Under construction Monitoring web page Monitoring webpage is in preparation ... Under construction

Comment Note CGMS37 Recommendation It is reasonable to “Combine” the GEO-LEO ray-match approach with another calibration approach using invariant target. I agree that cloud target is important and more study should be done. The algorithm to retrieve the input data to vicarious calibration, i.e., atmospheric profile, aerosol, and cloud, should be consistent with the radiative transfer code for simulation. (e.g. If the input data is retrieved by using the code 6S, the simulation of radiance should be examined by using 6S.) Validation method is also necessary. Note CGMS37 Recommendation CEOS WG CV and GSICS to study and report on inter comparisons of vicarious calibrations and trends in visible channels obtained from various land sites.

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