AMSU-A onboard Metop-A, B anc C

[nicolas meyus]

Hi,

I would like to know if AAPP treats AMSU observations differently for Metop-A, -B, and -C when determining brightness temperatures. In other words, does AAPP consider the AMSU-A instrument to be strictly identical across Metop-A, B, and C, or does it apply platform-specific calibrations?

Regards,
Nicolas.

[Nigel Atkinson]

Dear Nicolas,

Yes, AAPP does have some instrument specific constants that are applied during the calibration (amsuacl). They are in the amsua_clparams.dat file.

Some of the variables are used for quality control, such as the gross limits for warm and cold calibration counts (channel-dependent). Other variables have an influence on the brightness temperatures, such as the nonlinearity parameters and the warm and cold corrections. There are also some engineering constants such as the polynomial coefficients to concert PRT counts to physical temperature.

Reference: Mo, 1996.

Then in the preprocessing (atovin), when converting from antenna temperatures to brightness temperatures, there are antenna pattern corrections that are also instrument specific. These are held in fdf.dat.

Regards,

Nigel

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