NOAA-11 AVHRR/2 - THERMAL CHANNEL CALIBRATION UPDATE

Central wavenumber values for the thermal channels of the Advanced Very High Resolution Radiometer/2 (AVHRR/2) sensor onboard the NOAA-11 satellite have been re-evaluated. The NOAA-11 AVHRR/2 central wavenumber values were incorrectly specified on the launch of the satellite (Planet 1988) and in the subsequent editions of the NOAA Polar Orbiter Data Users Guide (Kidwell 1991 a, b). This Letter lists the correct values of the NOAA-11 AVHRR/2 central wavenumbers and details the differences that use of these corrected values makes to estimates of derived brightness temperature. Resultant changes in channel 3 and 4 brightness temperature are found to be insignificant but channel 5 brightness temperatures are 0.34-0.44 deg K higher than those calculated with the incorrect central wavenumbers. Updating the central wavenumbers is shown to cause 'split window' sea surface temperature estimates to decrease by 0.6-1.7 deg K whereas 'triple-window' estimates generally decrease by 0.34-0.42 deg K.