REGIONAL CLIMATE MODEL SIMULATION OF THE CLIMATE EFFECTS OF THE THREE GORGE RESERVOIR WITH SPECIFIC APPLICATION TO THE SUMMER 2006 DROUGHT OVER THE SICHUANG-CHONGQING AREA

High resolution multi-seasonal regional climate model experiments were conducted to simulate the effects of the Three Gorge Reservoir(TGR) on the climate of the surrounding region,with specific application to the summer of 2006 severe drought over the Sichuan-Chongqing area,or Three Gorge Area(TGA).A 50×50 km resolution simulation with the domain covering the whole China was first completed.Then two double nested simulations were carried out at a 10-km grid spacing over the TGA,one without the inland water coverage of TGR and the other with.A sub-grid method was employed in these two simulations to make the final model resolution to be 2 km×2 km(10-2 km simulations).Results show that the 50-km model reproduces the basic climatology and the anomaly of the summer temperature and precipitation over China,including the heat wave and drought over the Sichuan-Chongqing area.The 10-2 km resolution simulation provides with more detail of local climate over TGA.Sensitivity experiments with and without the TGR showed that this had little or negligible effects except right over the TGR area.The averages of the changes over the area are very small both for temperature and precipitation.Most of the changes in the grid points are not statistically significant on the 90% level while most of the significant changes in temperature are found to be located over the water body of TGR.The changes show more noise than systematic effects outside the TGR.In summary,the heat wave and drought event over the Sichuan-Chongqing area in the summer of 2006 can be more attributed to the large-scale circulation than to a local forcing.Contribution of the TGR is negligible.