Outgoing longwave radiation from the TOVS Pathfinder Path a data set

Abstract

A new outgoing longwave radiation (OLR) and clear-sky outgoing longwave radiation (COLR) data set derived from the Goddard TIROS operational vertical sounder (TOVS) Pathfinder Path A retrievals is introduced. Comparisons of OLR and COLR from TOVS Path A and the. Earth Radiation Budget Experiment (ERBE) have been carried out for the period February 1985 to May 1989. In the OLR comparison, advanced very high resolution radiometer (AVHRR) OLR has also been included. The mean OLR differences and standard deviations of the differences between TOVS and ERBE are, in general, within 5 W m-2. The differences AVHRR minus ERBE, and AVHRR minus TOVS OLR are close to -4 and -7 W m-2, respectively. However, over oceanic subtropical regions, AVHRR OLR differs by -8 to -12 W m-2 compared with the other two data sets. The differences of TOVS and ERBE COLR over most regions are within ±4 W m-2, with standard deviations of differences between 4 and 12 W m-2. The OLR and COLR data sets have larger discrepancies over snow/ice-covered polar regions. Interannual variability of the OLR and COLR are compared for 1986-1988 in terms of their monthly mean anomalies. The global mean monthly ERBE OLR and COLR anomalies have somewhat larger magnitudes (-3.0 to 1.5 and -2.0 to 1.0 W m-2, respectively) compared with the other data sets (-1.0 to 1.0 and -0.7 to 0.7 W m-2, respectively). Both sets of ERBE anomalies appear to be influenced by the change of satellite from NOAA 9 to NOAA 10. The results of this study indicate that TOVS Path A and ERBE OLR and COLR are of comparable accuracy. The TOVS Path A data set covers a substantially longer time period (1985-1998) than ERBE and would be very useful in climate research studies. Copyright 1999 by the American Geophysical Union.