Simulation of regional climate change under IPCC A2 scenario in southeast China

Abstract: A variable-grid atmospheric general circulation model, LMDZ, with a local zoom over southeast China is used to investigate climate changes in terms of both means and extremes in southeast China. Two time slices of 30 years are chosen to represent respectively the end of the 20th century and the middle of the 21st century. The boundary conditions were taken from the outputs of three global coupled climate models: Institut Pierre-Simon Laplace (IPSL), Centre National de Recherches Météorologiques (CNRM) and Geophysical Fluid Dynamics Laboratory (GFDL). Some preliminary results from a two-way nesting system between LMDZ-global and LMDZ-regional are also presented. The evaluation of simulated temperature and precipitation for the current climate shows that LMDZ reproduces generally well the spatial distribution of mean climate and extreme climate events in southeast China, but the model has systematic cold biases in temperature and tends to overestimate the extreme precipitation, the two-way nesting model can reduce the “cold bias” to some extent compared to the one-way nesting model. Scenario results using A2 emissions show that in all seasons there is a significantly increase for mean, daily-maximum and minimum temperature in the entire region, associated with a decrease in the number of frost days and with an increase in the heat wave duration. The magnitudes and main spatial patterns of the changes in temperature extremes show a quite good consistency among the three global scenarios and between the one-way and two-way nesting models. A warming environment will also give rise to changes in extreme precipitation events. Precipitation extremes are projected to increase over most of southeast China, and this in a quite consistent manner among the three global scenarios.

Keywords: climate change, climate extremes, variable-grid model, southeast Chinac