The in-flight two-point calibration of the AVHRR-2 radiometer introduces an error in the brightness temperature derived from the 11 mu m and 12 mu m channels, due to the non-linearity of the sensor response. The NOAA Users' Guide recommends assuming a negative value for the open space radiance to reduce this error for the range 225-310 K. This range however is too large for typical sea surface temperature variations, and differences as great as 0. 4 deg K are still present in the derived 11 mu m brightness temperature. This error is further amplified in the sea surface temperature, when estimated with the split window technique, as can be shown by radiative transfer model calculations. For this reason, a new practical calibration scheme is proposed to minimize the error due to the non-linearity of the sensor response, over the range of radiances from the sea surface.
IMPROVED CALIBRATION SCHEME FOR AVHRR-2.
Viola;
1987
Abstract
The in-flight two-point calibration of the AVHRR-2 radiometer introduces an error in the brightness temperature derived from the 11 mu m and 12 mu m channels, due to the non-linearity of the sensor response. The NOAA Users' Guide recommends assuming a negative value for the open space radiance to reduce this error for the range 225-310 K. This range however is too large for typical sea surface temperature variations, and differences as great as 0. 4 deg K are still present in the derived 11 mu m brightness temperature. This error is further amplified in the sea surface temperature, when estimated with the split window technique, as can be shown by radiative transfer model calculations. For this reason, a new practical calibration scheme is proposed to minimize the error due to the non-linearity of the sensor response, over the range of radiances from the sea surface.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
