Modeled Areal Evaporation Trends over the Conterminous United States

Long-term (1961–1990) areal evapotranspiration (AE) has been modeled with the help of 210 stations of the Solar and Meteorological Surface Observation Network within the conterminous United States. Modeled AE, averaged over all stations, has shown an overall increase of about 2–3% in the period 1961–1990, both on an annual basis and over the warm season (May–September). The rate of increase has differed among three geographic regions: the eastern, central, and western United States, with the largest modeled increase found in the east, followed by the central part of the United States. In the western part of the continent, modeled AE has, in fact, stayed constant. Of these trends, only the ones over the eastern part of the conterminous United States are statistically significant.