Synergism of SeaWinds and AMSR

Because of the conservation of mass, the divergence of the moisture transport integrated over the depth of the atmosphere should balance the fresh water flux (evaporation-precipitation) at the surface. Monitoring these two terms is critical to the characterization of the hydrological cycle and climate change. Direct in situ measurements of moisture transport, evaporation, and precipitation are extremely sparse over ocean. The three terms were estimated independently using spaceborne microwave scatterometer and radiometers and the similar geographical distribution, as shown in the figure, is one of the best validation of the estimation technique and a clear demonstration of the science synergism of the two instruments. (courtesy of W. iii ABSTRACT A combination of spaceborn scatterometer and radiometer provides us with instantaneous observation of various physical parameters of air-sea interface, such as wind speed and direction, water vapor content, sea surface temperature (SST), and rain rate, which are essential to scientific studies of global climate changes. The combined observation also plays an important role in the operational applications, such as weather forecast and disaster prevention. The Japanese earth observation satellite, Advanced Earth Observing Satellite-II (ADEOS-II), which carried a microwave scatterometer, SeaWinds, and a microwave radiometer, Advanced Microwave Scanning Radiometer (AMSR), was launched by the National Space Development Agency of Japan (NASDA) in December 2002, and the simultaneous observation was started. However, ADEOS-II failed in October 2003. A follow-up mission is required to continue the data flow for the operational applications and scientific studies. The Japan Aerospace Exploration Agency (JAXA) is now proposing a new mission called Global Change Observation Mission-W (GCOM-W) that will carry a microwave scatterometer and radiometer. This mission will also offer unique opportunities to address key issues of the Earth Science Enterprise (ESE) at the National Aeronautics and Space Administration (NASA). The simultaneous operation of the active and passive microwave sensors will contribute to improve sensor algorithms to estimate physical parameters. The radiometer measurements will be used by the scatterometer for rain flagging and improving wind retrieval under rain. Scatterometer wind will be able to correct wind direction dependence of the radiometer measurements. The simultaneous observation of the water vapor, precipitation and marine surface vector winds will have a significant impact on studies of the water-energy cycle, which is one of the most important scientific topics and social issues. The mission will provide a unique data set to investigate the balance among horizontal convergence/divergence of the water vapor, evaporation …