Abstract
In an atmospheric general circulation model (AGCM), the physical bounds on soil moisture content and the nonlinear relationship between soil moisture and evaporation lead to distinct geographical patterns in key surface energy and water balance variables. In particular, simple hydrological considerations suggest—and extensive AGCM simulations confirm—that the variance and skew of seasonally averaged [June–August (JJA)] air temperature on the planet should be maximized in specific, and different, regions: a variance maximum should appear on the dry side of the soil moisture variance maximum, and a positive skew maximum should appear on the wet side of the temperature variance maximum. These ideas are tested with multidecade observational temperature data from the Global Historical Climatology Network (GHCN). In the United States, where sufficient data exist, the predicted patterns in the seasonal temperature moments show up where expected. These results suggest that hydrological considerations do indeed control the patterns of seasonal temperature variance and skew in nature.
Corresponding author address: Randal Koster, Global Modeling and Assimilation Office, Code 610.1, NASA Goddard Space Flight Center, Greenbelt, MD 20771. Email: randal.d.koster@nasa.gov
