1. 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

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

3. 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

4. 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.
Aerosol
Cloud-free ocean
Cloud-free land
Aerosol
Cloud
Liquid cloud top 4

5. 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

6. 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

7. 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

8. 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

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

10. 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.

11. Thank you !