21世纪增暖情景下西北太平洋热带气旋频数的预估

摘要

利用IPCC发布的5个全球气候模式在高(SRESA2)、低(SRES B1)两种不排放情景下的预报集成结果,对21世纪大尺度环境进行分析,进而对西北太平洋夏季热带气旋(TC)的频数进行预估.结果表明:两种情景下热带西北太平洋均呈现500 hPa位势高度偏高、太平洋东部海表温度偏高、低层菲律宾以东为异常反气旋性环流控制的特征.这种大尺度环境不利于TC生成,在高排放情景下或21世纪中叶后该环境特征更显著.未来TC频数总体呈减少的趋势,低排放情景下的TC频数变化趋势比高排放情境下平缓,TC频数存在年代际和年际变化.%Using the forecasts of the five general circulation models distributed by the IPCC, the large-scale environment over the western North Pacific (WNP) under the high (SRES A2) and low (SRES B1) emission scenarios in the 21st century are projected. The results show that the 500 hPa geopotential height over the tropical WNP and the sea surface temperature, especially in the east-central tropic Pacific, both will be above normal. Furthermore, the low-level anomalous anti-cyclonic circulation will cover the region east to the Philippines in the 21 st century. Thus the large-scale environment will not be conducive to the formation of tropical cyclones (TCs), and such an environment will be more remarkable under the SRES A2 scenario or after the mid-21st century. The frequency of TC will possibly decline, but the decreasing trend under the SRES Bl scenario will be weaker than that under the SRES A2. There will still be interdecadal and interannual fluctuations of TC frequency in the 21st century.