Abstract
Regional climate change arises from two processes which, in the real climate system, cannot be separated from each other: local radiative forcing and advection of air masses from regions which themselves have been subject to climate change. In this study, we present an experimental design based on a regional climate model allowing for the assessment of global and local effects on future climate change in Asia. We carry out two runs which are characterized by increasing greenhouse gas concentrations within the model domain, but one (the control run) is one-way nested into a global control run at the lateral and oceanic boundaries while the other (the forced run) is one-way nested into a consistently forced global simulation. The aim is to improve our understanding of the mechanisms of climate change in a regional context. It turns out that temperature and precipitation changes in Asia are indeed mostly related to changes in the advected air masses which enter along the lateral boundaries. Regionally confined greenhouse forcing only affects the atmospheric heating rate while precipitation and atmospheric circulation features remain more or less unchanged. Temperature changes in the forced experiment are partly governed by warmer air masses penetrating the lateral boundaries and partly by a modification of atmospheric circulation processes, including a tendency towards a double-trough structure over Central Asia and changing temperature advection. The trend pattern of precipitation is much more heterogeneous in space but can partly be attributed to changes in horizontal wind divergence and vertical velocity.
Published Version
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