Improved TOA broadband shortwave and longwave fluxes derived from satellites over the Tropical Western Pacific

Satellites provide valuable data coverage over large-scale regions. Their continuous monitoring of radiative properties, such as top-of-atmosphere broadband longwave and shortwave fluxes, can be a useful tool for evaluating climate change and studying cloud radiative interactions. One region of particular climatic importance is the Tropical Western Pacific region. This area was viewed by the Geostationery Operational Environmental Satellite-9 (GOES-9) from May 2003-October 2005, and is currently covered by MTSAT. While these geostationary satellites provide large-scale coverage, the narrowband visible and infrared measurements provide only a small portion of the total radiative flux. In order to derive broadband fluxes from this data, empirical narrowband-to-broadband flux conversion fits have been derived by matching twice-daily coincident broadband fluxes from the CERES instrument aboard the Terra satellite. The GOES-9 and MTSAT filter functions are quite different and, therefore, distinct fits are required for each.

Shortwave and longwave NB-BB fits for day and night, derived separately for dry (May-October) and wet (November-April) seasons, have been implemented within the VISST (Visible Infrared Solar Split-Window Technique) satellite cloud and radiative property retrieval framework. Fits derived for the entire GOES9 record (May03-Oct05), and for selected MTSAT data in 2007, are used to derive broadband fluxes covering the TWP region for these time periods. Validation will be performed with respect to available CERES fluxes, as well as modeled fluxes derived from Fu-Liou radiation code. This work represents ongoing efforts to provide a complete cloud and radiative property dataset for the TWP, covering 10°N-20°S, 120°E-180°E, from May 2003 to the present.