Errors in high‐latitude SSTs and other geophysical products linked to NOAA‐14 AVHRR channel 4 problems

Abstract
Errors in brightness temperatures for channel 4 in the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA‐14 spacecraft are examined. The errors involve a low frequency of occurrence for some values, and a corresponding enhancement of frequency for others. Errors appear to be related to the conversion of analog to digital values. Unfortunately, it is not possible to identify and separate erroneous values. The most apparent errors in geophysical products derived from AVHRR's channel 4 occur at low brightness temperatures, therefore sea surface temperatures in high latitudes (below about 6°C) and cloud‐related products must be used with caution, as they may have systematic errors as large as 0.5°C.