A simplified method for estimating the total water vapor content over sea surfaces using NOAA-AVHRR channels 4 and 5

A simplified method for estimating the total amount of atmospheric water vapor, , over sea surfaces using NOAA-AVHRR Channels 4 and 5 is presented. This study has been carried out using simulated AVHRR data at 11 and 12 m (with MODTRAN 3.5 code and the TIGR database) and AVHRR, PODAAC, and AVISO databases provided by the Louis Pasteur University (Strasbourg-France), NASA-NOAA, and Météo France, respectively. The method is named linear atmosphere–surface temperature relationship (LASTR). It is based on a linear relationship between the effective atmospheric temperature in AVHRR Channel 4 and sea surface temperature. The LASTR method was compared with the linear split-window relationship (LSWR), which is based on a linear regression between and the difference of brightness temperature measured in the same channels ( = 4 5). The results demonstrate the advantage of the LASTR method, which is capable of estimating from NOAA-14 afternoon passes with a bias accuracy of 0.5 g cm 2 and a standard deviation of 0.3 g cm , compared with the obtained by the AVISO database. In turn, a global bias accuracy of 0.1 g cm 2 and a standard deviation within 0.6 g cm 2 have been obtained in comparison with the included in the PODAAC database derived from the special sensor microwave/imager (SSM/I) instrument.