Diurnal to Annual Precipitation Sensitivity to Convective and Land Surface Schemes

Abstract

Precipitation?s diurnal to annual variance distribution and atmospheric water cycle component interactions are examined globally for sensitivity to convective and land surface schemes. The main regional features of statistics identified in previous reanalyses are robust in unconstrained continuous simulations corresponding to the reanalyses? convective and land surface schemes. A change from the simplified Arakawa?Schubert (SAS) to the relaxed Arakawa?Schubert (RAS) convection scheme reorganizes the variance of rainfall at low latitudes to a redder spectrum. Despite the potential increase in soil moisture memory, a change from the Oregon State University (OSU2) to the Noah land surface model does not noticeably affect the variance distribution of precipitation. The competition between dynamic and thermodynamic sources of precipitation?s variability is affected by the choice of both the land surface model and the convective scheme. Noah reduces evaporation?s role over land, with vapor convergence compensating, while RAS/SAS sensitivities result in complex regional redistributions of component covariance.