TRMM Tropical Rainfall Measuring Mission
3B42 V6, RTThe combined instrument rain calibration algorithm (3B-42) uses an
optimal combination of 2B-31, 2A-12, SSMI, AMSR and AMSU precipitation estimates (referred to as HQ), to adjust IR estimates from geostationary IR observations. Near-global estimates are made by calibrating the IR brightness temperatures to the HQ estimates. The 3B-42 estimates are scaled to match the monthly rain gauge analyses
used in 3B-43.
0.25 Deg 3-hourly 50N - 50S 1998-today
IRCPC IR Brightness Temperatures
The Climate Prediction Center/NCEP/NWS is now making available globally-merged (60N-60S) pixel-resolution IR brightness temperature data (equivalent blackbody temps), merged from all available geostationary satellites (GOES-8/10, METEOSAT-7/5 & GMS). The availability of data from METEOSAT-5, which is located at 63E at the present time, yields a unique opportunity for total global (60N-60S) coverage.
4km 1/2-hourly 60N - 60S 2000-today
IRP - IR derived Precipitation
Basic idea,
IR ~ Temperature
Cold ~ Clouds
Clouds ~ Precip
So,
IR ~ Precip
IRP in the W. Hemisphere
For each 1/4 degree pixel
and pentad (1-72)
for given month (2001-2009)
for given threshold (260-300K)
regress (TRMM daily rain rate) onto (%IR below TH)
Find the TH with the best correlation,
that becomes your model for that point
Apply this to .05 degree IR data to get .05 deg IRP
FTIPP Calculations
FTIPP = FCLIM * (%TRMM + %IRP)/2
%TRMM = (TRMM.data + ) / (TRMM.clim + )%IRP = (IRP.data + ) / (IRP.clim + )