摘要
台风路径一直是天气预报的难点之一。本文研究了大气季节内振荡(ISO)对西北太平洋台风路径的影响,指出大气ISO对台风路径预报有重要参考意义。细化传统台风路径的划分方法,将台风路径进一步分为5种:西移型、西北移型、日本以西型、日本登陆型、日本以东型。分别对不同路径的台风所对应的低频流场进行超前滞后合成分析,发现台风生成时850hPa低频气旋的正涡度带走向往往预示着台风的未来走向,200hPa低频环流形势,意味着上层引导气流的方向,对台风的路径也有一定的指示作用。低频流场演变特征表明,大气ISO在对流层低层到中层通过低频气旋或低频反气旋的环流形势影响季风槽及副热带高压的位置和强度,从而影响台风的活动。低频气旋的作用使台风易于沿着低频气旋的正涡度带移动。菲律宾以东热带地区生成的低频气旋的加强有利于季风槽的加强和东伸,另外,它的经向北传对副热带高压的位置也有影响。在副热带地区存在大气ISO流型以低频波列的形式向西传播,对副热带高压的季节内时间尺度东西振荡有重要作用。热带与副热带地区大气ISO的共同作用,对台风路径有决定性意义。初步认为,对于西移路径和西北移路径,热带大气ISO的影响起着更为重要的作用;对于日本登陆型和日本以东型路径,副热带大气ISO的影响起着更为重要的作用。大气季节内振荡的环流场可以作为台风路径预报的依据之一。
Based on in-situ observed summertime air temperatures（OT） from 194 stations in China,NCEP/NCAR reanalysis 2-m temperatures（NT） and ERA-40 reanalysis 2-m temperatures（ET） on a monthly basis,a study is performed of the periods,variance,interannual and interdecadal variability of these temperature series by means of linear analysis,variance and wavelet treatments as well as EOF decomposition.Results suggest that（1） the values,anomalies,and trends are very close between the ET and the OT;the NT are lower compared with the OT and prior to 1965 the NT magnitudes and anomalies differ significantly from those of the OT and the ET,with higher similarity of the ET to the OT than that of the NT.Thus,in making periodic analysis of surface temperature,the ET are superior.Caution should be taken when the NT are applied,but their departures are somewhat credible after 1965.（2） The ET have similar linear trend and spatial mode to the OT,the trend of the NT is much greater compared with those of the OT and the ET,and the ET have higher ability to reproduce temperature trends in China on a long-term basis than the NT,which show uncertainties in long-range temperature variations in China.（3） The ET and the NT are capable of revealing the spatio-temporal patterns and variations of temperatures in China,but the ET are more correct,especially when the interdecadal variability is investigated of the temperatures in northern China north of 30°N.It is found that the ET and the NT have comparable ability to show the interannual variations.（4） The differences before and after 1976 in China are obvious in the three temperature datasets,with almost identical（not entirely coincident） trends and spatial distributions between the ET（the NT） and the OT.In addition,the NT before 1965 have a drawback similar to that of ＂PSFC＂,a problem that should not be ignored.
出处
《大气科学》
CSCD
北大核心
2010年第3期559-579,共21页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目2009CB421401
国家自然科学基金资助项目U0833602
国家自然科学基金资助项目40875049
关键词
台风路径
大气季节内振荡
季风槽
副热带高压
observations
NCEP/NCAR
ERA-40 project
surface temperature
climatic variability
