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摘要
NEX-GDDP data has the advantages of high resolution and uniform resolution with all the models. However, there are few studies on evaluating the NEX-GDDP’s ability to simulate the extreme climate on the Qinghai-Xizang Plateau. Based on the daily observation dataset of meteorological stations for the period of 1986-2005 over the Qinghai-Xizang Plateau, this study selected ten extreme climate indices, i. e. , Frost days (FD) , Ice days (ID) , Min Tmin (TNn) , Max Tmax (TXx) , Warm spell duration indicator (WSDI) , Cold spell duration indicator (CSDI) , annual Total wet-day precipitation (PRCPTOT) , Consecutive dry days (CDD) , Consecutive wet days (CWD) and Max 1-day precipitation amount (Rx1day) , which can directly reflect the influence of climate change on social and economic activities and geographical landforms in the plateau area, and comprehensively evaluated the abilities of 21 models that participate the NASA Earth Exchange/Global Daily Downscaled Projection (NEX-GDDP) in simulating extreme climate indices. The main conclusions are drawn as follows: (1) Except for the average values of TNn and TXx calculated by all models are lower than the average values calculated from observation dataset, the average values of other extreme climate indices calculated by all models are higher than the average values calculated by observation dataset. With respect to the variation trend of extreme climate indices, the FD, ID, CSDI and CDD trends calculated by observation shows strong consistency with those calculated by all models while weak consistency was seen for others extreme climate indices. (2) Large differences in spatial simulation ability can be seen among the 21 models, and in terms of correlation coefficient (r) , the spatial simulation ability of all the models is better than that of time sequential simulation ability, while in terms of root mean square error (RMSE) , the ability of sequential simulation ability is better than that of spatial simulation. (3) According to the data used to identify the extreme climate indices, the extreme climate indices is divided into three categories:daily minimum temperature category (FD, TNn and CSDI) , daily maximum temperature category (ID, TXx and WSDI) and daily precipitation category (PRCPTOT, CDD, CWD and RX1day). Based on the 21 models’abilities to simulate the spatio-temporal variations of the extreme climate indices, five optimal modes for three extreme climate indices were selected as follows:① daily minimum temperature category:GFDL-ESM2G, GFDL-CM3, CCSM4, MIROC5 and ACCESS1-0. ② daily maximum temperature category:CanESM2, BNU-ESM, MIROC-ESM-CHEM, inmcm4 and CCSM4. ③ daily precipitation category:BNU-ESM, CanESM2, CSIRO-Mk3-6-0, MIROC-ESM and MIROC-ESM-CHEM. Based on the above statements, the above optimal models are recommended when the NEX-GDDP is used to investigate the extreme climate change over the Qinghai-Xizang Plateau in the future.
