Synoptic-based evaluation of climatic response to vegetation change over southern Africa

摘要

The results of regional climate model (RCM) simulations of the effects of vegetation change in southern Africa are analysed to asses the role of synoptic forcing in land atmosphere interactions. A self-organizing map (SOM) is used to identify the dominant large-scale features in the atmospheric boundary conditions used to force the RCM. The fields used to characterize the large-scale circulation are geopotential height at 850 and 500 hPa and total precipitable water between these two levels. For each of the patterns (nodes) identified in these variables by the SOM, the mean RCM-simulated response to vegetation change is evaluated. Notable differences are seen in the response of precipitation, near-surface temperature and geopotential heights to the land surface change between different nodes. Conditions characterized by strong sub-tropical anticyclones and low atmospheric moisture show the greatest temperature and geopotential height changes and are most sensitive to changes in radiative fluxes, whereas precipitation and surface hydrological processes are more sensitive under conditions of weak subsidence and high levels of atmospheric moisture. Copyright (C) 2009 Royal Meteorological Society