北大西洋热带气旋生成频数变化对海温异常响应特征的研究

CONTRIBUTION OF MAJOR SSTA MODES TO TROPICAL CYCLONE GENESIS FREQUENCY OVER THE NORTH ATLANTIC

利用美国国家飓风中心(National Hurricane Center,NHC)的Best Track Data(HURDAT2)数据和美国国家预报中心/大气研究中心(NCEP/NCAR)大气再分析资料,运用广义平衡反馈分析方法(GEFA),研究多个海盆主要海表温度异常(SSTA)模对北大西洋热带气旋生成频数(TCGN)气候变率的强迫作用。(1)北大西洋TCGN的气候变率对北大西洋三极型模态(NA1)和太平洋mega-ENSO式模态(P1)具有显著的响应,对应的响应振幅分别为0.45和-0.28,即当NA1(P1)的时间系数增加(减小)1个标准差时,北大西洋TCGN将增加0.45(0.28)个。(2)TCGN对NA1、P1的气候变率、年代际变率有显著响应,但对年际变率响应不显著。(3)北大西洋TCGN在1995年前后发生异常变化,从平均8个增加到12.6个,NA1、P1对1995年后的TCGN异常增加的贡献分别为27%、45%。(4)NA1对北大西洋TC环境场的强迫中心多集中在20°N附近,而P1的多位于20°N以南以及墨西哥湾地区,为TC生成提供有利的动力和热力条件。

IContribution of major sea surface temperature anomaly(SSTA)modes to tropical cyclone genesis frequency(TCGN)over North Atlantic are analyzed based on the Best Track Data(HURDAT2)of National Hurricane Center(NHC)in 1970—2017、the monthly mean SST data of Hadley Center of sea ice and SST、NCEP/NCAR reanalysis monthly mean data and the generalized equilibrium feedback assessment(GEFA)method.The main conclusions are as follows:(1)TCGN climatic variability in North Atlantic has a significant response to NA1 and P1,the feedback intensities are 0.45 and-0.28.(2)TCGN interdecadal variability in North Atlantic has a significant response to NA1 and P1,but the response is non-significant when it comes to interannual variability.(3)The average of TCGN in 1970—1995 is 8,while it rises to 12.6 in the later period.The contributions of NA1 and P1 in the later period GEFA are 27%and 45%.(4)When it comes to the local environment,the significant response areas to NA1 are located in 20°N.And the significant response areas to P1 are located in south of 20°N and the gulf of Mexico.