中国地区IPCC A1B情景下21世纪中期气候变化的数值模拟试验

A numerical simulation for mid-21st century climate change over China under IPCC A1B scenario

利用MM5V3区域气候模式单向嵌套ECHAM5全球环流模式的结果,对中国地区实际温室气体浓度下当代气候(1981—2000年)及IPCC A1B情景下21世纪中期气候(2041—2060年)分别进行了水平分辨率为50 km的模拟试验。首先检验全球和区域模式对当代气候的模拟情况,结果表明:区域模式对中国地区地面温度和降水空间分布的模拟能力优于全球模式;与实际观测相比,区域模式模拟的地面温度在中国大部分地区偏低,模拟的降水量偏多,降水位置偏北。IPCCA1B情景下中国地区21世纪中期气候变化的模式结果显示:各季节地面温度在全国范围内都将比当代升高1.2～3.9℃,且升温幅度具有北方大于南方、冬季大于夏季的时空分布特征;降水变化具有一定的区域性和季节性,秋季和冬季降水在全国大部分地区都将增加10%～30%,春季和夏季降水则呈现"北方减少、南方增多"的趋势,变化幅度在-10%～10%之间。21世纪中期地面温度和降水变化还具有一定的年际特征:地面温度在中国地区各子区域均表现为上升趋势,升温速率在0.7～0.9℃/10a之间,温度变率也比当代有所增大;降水在西北地区略呈下降趋势,在其它子区域均为上升,降水变率的变化具有区域性特征。

This paper analyzes the both 20-year simulations by MM5V3 regional climate model,which is nested in one-way mode within ECHAM5 general circulation model.Two sets of 50 km grid spacing simulation for present climate（1981-2000,real CO2 scenario） and mid-21st century climate（2041-2060,IPCC A1B scenario） over China are conducted.Present climate simulation results show that MM5V3 model has the better capability to simulate the spatial patterns of surface air temperature and precipitation when comparing to ECHAM5 model,though in most areas surface air temperature is underestimated and precipitation is overestimated.The climate change simulation by MM5V3 under IPCC A1B scenario indicates that the seasonal mean surface air temperature will increase 1.2-3.9 ℃ in mid-21st century,with a stronger trend in winter and the increasing magnitude from south to north.The seasonal precipitation undergoes a significant change as well.Autumn and winter mean precipitation will remarkably increase with a range of 10% to 30% over most parts of China.Meanwhile,spring and summer mean precipitation will increase in southern China and decrease in northern China both about-10% to 10%.Furthermore,the changes of surface air temperature and precipitation also have the inter-annual characteristics.Annual mean surface air temperature indicates the increasing trend in all sub-regions,with the increase rate by 0.7-0.9 ℃/10 a.The variability of surface air temperature will increase in all sub-regions.Annual mean total precipitation also shows the increasing trend in all sub-regions except Northwest China.