Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle: Focus on Shortwave and Longwave Radiative Fluxes

The overall goal of this MEaSUREs Project is to develop consistent, long-term Earth System Data Records (ESDRs) for the major components of the terrestrial water cycle at a spatial resolution of 0.5 degree at climatic time scale. The shortwave (SW) and longwave (LW) radiative fluxes at the Earth's surface determine the exchange of energy between the land and the atmosphere and consequently, control the hydrologic cycle. Environmental satellites are considered as useful tools for providing information on surface radiative fluxes at various temporal and spatial scales, allowing improvement in estimation of terrestrial water and energy storage and oceanic heat fluxes. During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, at present, satellite based estimates differ from each other and long term observations at global scale are not readily available. There is a need to utilize existing records of satellite observations and to improve currently available estimates. This requires updates to inference schemes so that new knowledge and most recent auxiliary information can be fully utilized. This paper reports on improvements introduced to an existing methodology to estimate shortwave (SW) radiative fluxes within the atmospheric system, on the development of a new inference scheme for deriving LW fluxes, the implementation of the approach with the ISCCP DX observations and improved atmospheric inputs for the period of 1983-2007, evaluation against ground observations, and comparison with independent satellite methods and numerical models. The resulting ESDRs from the entire MEaSUREs Project are intended to provide a consistent basis for estimating the mean state and variability of the land surface water cycle at a spatial scale relevant to major global river basins. Supported under NASA Grant NNX08AN40A, NRA/Research Opportunities in Space and Earth Sciences-2006.