CERES ADM

[zhengyueyueming]

I am very confused about the CERES ADM validation section. I want to know if the direct integration method mentioned in flux validation can only be used when CERES is in RAP mode.
(Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth’s Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part II: Validation)

[ASDC - cheyenne.e.land]

Hello,

Taking one season in 2002 for Terra as an example, the directly integration approach is:

1. construct one set of regional (10x10-degree) all-sky ADMs by using both cross-track and RAP observed radiances in JJF 2002, in this sample, ~184 days of observations of FM1 and FM2 are used.
2. construct another set of all-sky ADMs corresponding to (1) by predicted radiances from Terra ADMs in the same period.
3. Apply ADMs in (1) and (2) to cross-track observations in July 2002, convert the fluxes to the 24h averages, and evaluate the differences.

Thanks,

[zhengyueyueming]

Thank you so much sir,
Can the flux obtained in RAP mode be considered as the true value? This is because it captures radiance from all directions, right? According to the scanning modes displayed on the CERES website, I downloaded data for specific dates when the RAP observation mode was active, such as Terra being in RAP mode on July 16, 2022. The flux in this data is derived from radiances observed from various directions, correct? Can I consider this as the true flux to validate other products?

[ASDC - cheyenne.e.land]

Hello,

In terms of quality, the flux obtained in cross-track should be considered better than that obtained in RAP mode. The flux uncertainties obtained from RAP mode are larger than that in cross-track. The data collected in RAP mode are mainly used to build ADMs, the empirical model to invert flux from directional measurements of radiances.
Particularly, because Terra's orbit is unable to maintain its nominal height now, the height of its orbit becomes lower and equatorial cross-time moves away from 10:30 AM. The purpose of putting Terra in RAP mode from 2021 is mainly for the future research purposes and using of fluxes inverted from RAP mode should take caution.

Thanks,
ASDC