Earth Radiation Budget: Results of Outgoing Longwave Radiation fromNimbus-7,NOAA-9, and ERBS Satellites

Abstract

Eighteen months of wide field-of-view (WFOV) outgoing longwave radiation (OLR) measurements from the Earth Radiation Budget Experiment (ERBE) NOAA-9 and NOAA-10 spacecraft have been deconvolved to produce resolution-enhanced flux maps at the top of the atmosphere. NOAA-9 had a 0230 LST equator-crossing time, and NOAA-10 a 0730 LST equator-crossing time. Intercomparison of these results with ERBE scanner and numerical filtered WFOV results is made. Results have also been compared with corresponding months of deconvolved results from the Nimbus-7 spacecraft (1200 LST equator crossing). Comparisons have been made of zonal profile plots of OLR for the different sensors and of contour maps of differences in OLR between sensors. In general Nimbus-7 OLR results show reasonable agreement with NOAA-9 and NOAA-10 over most regions of the globe. The largest differences occur over the extratropies, noticeably over land and especially over deserts. This study suggests that long-term monitoring of OLR with WFOV sensors is feasible for globally averaged trends to an accuracy of less than 1 W m−2, for the global absolute mean to within 3 W m−2, and for regional monthly means to within 8 W m−2 for most of the globe. Global averages for numerical filtered and deconvolved NOAA-9 WFOV results are consistently higher than Nimbus-7 deconvolved results because NOAA-9 results over land and deserts are higher. However, the ERBE NOAA-9 scanner gives smaller values of OLR over most regions ofthe globe than either the NOAA-9 WFOV numerical filtered or WFOV deconvolved results.