Updated ATOVS coefficient files for both RTTOV v5 and RTTOV v6 are now available from the NWPSAF web site at:
Satellites covered in the ATOVS files are NOAA-10 to NOAA-16.
They include the following changes to the original files:
NOAA-16 coefficients added
HIRS coeffs based on improved IR LbL transmittances (this changes the BTs by ~0.1K and the Jacobians have a spurious increase for the top level removed)
MSU/AMSU coeffs are based on improved Microwave LbL transmittances.
Changes in some channels are significant:
> AMSU
> Chan new-old BT degK
> 5 0.145
> 6 0.308
> 7 0.343
> 8 0.205
> 9 1.247E-03
> 10 -0.265
> 11 -0.464
> 12 -0.624
> 13 -0.978
> 14 -0.568
We believe the new transmittances lead to a better fit to the data
and other models.
Therefore if you use the new files you will see differences for ALL
satellites. Of course you can just cut and paste the file to add the NOAA-16
coeffs to your existing coef file if
you don't want to change the N-10 to N-15 simulations.
For both RTTOV v5 and RTTOV v6 you will need to update the cparam.h include file to add an extra NOAA satellite and recompile the code. You should set the parameters to:
INTEGER, PARAMETER :: JPNOAA = 12
INTEGER, PARAMETER :: JPTOVS = 16
Also posted on the web site are RTTOV v6 coefficients for NOAA-16 AVHRR
and the GOES-8/10/11 IR sounder channels (but note you need a software
patch available from
me to use the latter).
If you have any problems with these new files please let me know,
Roger Saunders
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