The joint initialization of land and atmospheric variables is considered in a supplemental series of ensemble monthly forecasts. For precipitation, the increases in forecast skill appear strongest in May through July, whereas for air temperature, they are largest in August and September. The land initialization does cause a small but statistically significant improvement in precipitation and air temperature forecasts in this region. The 75 separate forecasts provide an adequate statistical basis for quantifying improvements in forecast skill associated with land initialization.Įvaluation of skill is focused on the Great Plains of North America, a region with both a reliable land initialization and an ability of soil moisture conditions to overwhelm atmospheric chaos in the evolution of the meteorological fields. Their usefulness is tested in this regard by performing retrospective 1-month forecasts (for May through September, 1979–93) with the NASA Global Modeling and Assimilation Office (GMAO) seasonal prediction system. ![]() These fields can be used as initial conditions for precipitation and temperature forecasts with an atmospheric general circulation model (AGCM). ![]() Forcing a land surface model (LSM) offline with realistic global fields of precipitation, radiation, and near-surface meteorology produces realistic fields (within the context of the LSM) of soil moisture, temperature, and other land surface states.
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