Satellite-Based Climatologies Related to the Water Cycle

Abstract

The subject of “climate change” has stirred much interest worldwide over the past several decades. If indeed a global warming is underway, its impact on the global population could be catastrophic if decision makers are unprepared. Trends in variables such as snow cover and precipitation (i.e., components of the water cycle) are climate change indicators as they are coupled with temperature change. Global measurements from environmental satellites are crucial in obtaining estimates of such components. These measurements compliment surface measurements (which are restricted to populated land areas) and are the only source of information over ocean. Various long term records of water vapor, snow cover and precipitation have been established through the use of many satellite sensors. Polar orbiting environmental satellites (POES) offer global coverage while geostationary orbiting environmental satellite (GOES) offer more frequent observations than the POES, but do not provide global coverage. The research community has developed blending schemes to take advantage of the best attributes of all of the available satellite measurements and combine them with high quality ground measurements. In this manner, the best possible time series of variables related to the water cycle can be generated and maintained, and used to monitor climate variations. It is the purpose of this paper to describe the utilization of satellite measurements, illustrate some of the global monitoring applications of the time series and discuss what the future will bring.