西北太平洋强台风频数与ENSO年际联系的年代际变化机理研究

发布时间：2018-07-08 09:00

本文选题：西北太平洋 + 强TC频数　；参考：《南京信息工程大学》2014年硕士论文

【摘要】：本文主要利用美国国家环境预报中心(National Centers for Environmental Prediction,简称NCEP)及美国国家大气研究中心(National Center for Atmospheric Research,简称NCAR)1949-2008年的月平均再分析资料以及英国哈德莱观测中心(Hadley Centre)月平均海平面温度(SST)和美国关岛联合台风警报中心(JointTyphoon Warning Center,简称JTWC)每6小时定位时次best-track资料,分析西北太平洋强热带气旋(TC4、5)年频数与Nino3.4指数相关关系年代际变化的原因及可能机理。我们研究发现在1949-1968(第一阶段)和1989-2008(第三阶段)年间强TC年频数与厄尔尼诺-南方涛动(El Nino-Southern Oscillation, ENSO)关系密切分别为0.69和0.70,而在1969-1988年间(第二阶段)两者相关只有0.07。而且在第二阶段,强TC频数偏少,平均每年4.85个,第一、三阶段强TC频数却偏多,年平均分别为7.60和7.75个。不仅强TC年频数以及与ENSO的相关关系在第二阶段发生转变,其生成位置和路径在第二阶段与第一、三阶段也有差异,第二阶段,强TC主要生成在160°E以东,20°N以南,路径以西移为主,而第一、三阶段,强TC主要生成范围偏大,向北向东扩展,路径以向北转向偏多。以上的年代际变化的可能机理,通过分析结果表明：第二阶段与第一阶段相比强TC频数偏少,且与ENSO的相关关系较弱,主要是因为第二阶段在8-10月印度洋海温明显比第一阶段偏暖,导致西北太平洋和热带中太平洋地区有异常的反气旋,同时较高海平面气压和对流层输出温度,较低的中层比湿,这些因子对第二阶段的台风最大可能强度(Maximum Potential Intensity, MPI)指数在整个中北太平洋和南海地区的负异常均有贡献。此外,中层相对水汽较少、垂直风切变较强和高层辐合底层辐散,这些要素的变化导致第二阶段西北太平洋热带气旋生成东南象限的潜在生成指数(Genesis Potential Index, GPI)指数西北-东南走向的负异常。因此,在第二阶段的各个因子都不利于TC的生成和发展。对于生成位置与路径的转变,可以从引导气流看出：第二阶段赤道附近存在异常的东风气流和反气旋环流,导致强TC生成位置偏西偏南,路径以西移为主。而对比第三阶段与第二阶段,第三阶段8—10月在赤道中太平洋SST明显偏暖,在热源的西北侧即在西北太平洋激发气旋型Rossby波,从而产生气旋式环流,是第三阶段强台风频数增多,且与ENSO关系密切的原因,也对MPI指数的正异常有较大的贡献。MPI指数在赤道中太平洋较大,对于MPI指数的影响因子,除了SST,中层比湿的贡献也较大。此外,对于GPI指数的影响因子,中层相对湿度偏大,850hPa绝对涡度为正异常,这些要素导致第三阶段的GPI指数在西北太平洋东南部的正值中心。对于路径和生成位置,从引导气流可以看到,西北太平洋东南部存在较大的气旋性环流和向西向北的气流,有利于TC路径的转折,生成位置也向东向北扩展。同时还对不同类型的ENSO现象进行了分析,结果表明：中太平洋增暖CPW比东太平洋增暖EPW更有利于TC的发展,强TC频数偏多,而东太平洋变冷EPC与东太平洋增暖EPW相比则EPC不利于TC的增强,强TC频数偏少。此外,本文使用ECHAM4.6版模式,对以上年代际变化的可能机理通过一个控制试验和三个敏感性试验来模拟,一个控制性试验是使用观测到的气候月平均海温场进行的,三个敏感性试验分别为：第一阶段强迫热带印度洋增暖(TIO)、第二阶段强迫中太平洋增暖(CP)和热带印度洋和中太平洋同时增暖(TIO-CP)。分析结果表明：第一阶段与第二阶段的变化主要是因为第二阶段在8-10月印度洋海温明显比第一阶段偏暖,而对比第二阶段与第三阶段的变化,则是由于第三阶段8-10月在赤道中太平洋SST明显偏暖。
[Abstract]:In this paper, the monthly mean reanalysis data of the 1949-2008 years of the National Center for environmental prediction (National Centers for Environmental Prediction, abbreviated as NCEP) and the National Center for Atmospheric Research (National Center for Atmospheric Research, for short) and the monthly mean sea level of the UK's Hadley observation center are mainly used. Temperature (SST) and the United States Guam Joint Typhoon Warning Center (JointTyphoon Warning Center, abbreviated as JTWC) locate the time best-track data every 6 hours, analyze the causes and energy mechanism of the interdecadal variation of the annual frequency of the Northwest Pacific strong tropical cyclone (TC4,5) and the Nino3.4 index, and we have found that in the 1949-1968 (first stage) and 198. The strong TC year frequency in the 9-2008 (third stage) years and the El Nino Southern Oscillation (El Nino-Southern Oscillation, ENSO) are closely related to 0.69 and 0.70 respectively, while in the 1969-1988 years (second stage) the correlation is only 0.07. and in the second stage, the strong TC frequency is less, the average per year is 4.85, and the strong TC frequency is much more than the first, third stage. They are 7.60 and 7.75 respectively. Not only the strong TC year frequency and the correlation with ENSO change in the second stage, but also the formation position and path are also different in the second stage and the first, third stage. The second stage, the strong TC is mainly formed in the east of 160 E, 20 degree N to the west, and the path is moved westward, while the first, third stage, the strong TC generation range. The second stage of the second stage is less than the first stage, and the relative relationship with the ENSO is weak, mainly because the sea temperature in the India ocean is obviously warmer than the first stage in the second stage in the 8-10 month, leading to the northwest too much. There are abnormal anticyclones in the Pingyang and the mid tropical Pacific regions, with higher sea level and tropospheric output temperatures and lower middle level specific humidity. These factors contribute to the negative anomalies of the maximum possible intensity (Maximum Potential Intensity, MPI) of the second stage of typhoon in the Taiping ocean and the South China Sea. The relative water vapor is relatively less, the vertical wind shear is stronger and the high rise convergence bottom divergence. These changes lead to the negative anomaly of the Genesis Potential Index (GPI) index of the southeast quadrant of the northwestern Pacific tropical cyclone in the second stage. Therefore, all the factors in the second stage are not conducive to TC. Generation and development. For the transformation of the generating position and path, it can be seen from the guiding airflow that there is an abnormal easterly flow and anticyclone circulation near the second stage of the equator in the second stage, which leads to the westward deviation of the strong TC formation position and the main path westward, while the third and second stages are compared, and the third stage of the equatorial Pacific is obvious in the third stage from 8 to October. In the northwestern side of the heat source, the cyclone type Rossby wave is excited in the northwest side of the heat source, which produces cyclonic circulation, which is the third stage strong typhoon frequency, which is closely related to the ENSO, and also has great contribution to the positive anomaly of the MPI index. The.MPI index is larger in the equator and the Taiping ocean in the equator, and the factors affecting the MPI index are in addition to SST, The contribution of the layer to the humidity is also larger. In addition, the relative humidity of the middle layer is large and the absolute vorticity of the 850hPa is positive. These factors lead to the GPI index of the third stage in the positive center of the southeast of the Northwest Pacific. For the path and the generating position, the south-east of the Northwest Pacific can be seen larger from the guiding air flow. The cyclonic circulation and westward northward flow are beneficial to the turning of the TC path and the expansion of the generating position from the east to the north. At the same time, the different types of ENSO phenomena are also analyzed. The results show that the warmer CPW in the central Pacific is more conducive to the development of TC than the eastern Pacific, and that the strong TC frequency is more than that of the East Pacific, while the East Pacific is cooled EPC and the East Pacific. Compared with the increase of EPW, EPC is not conducive to the enhancement of TC, and the strong TC frequency is less. In addition, this paper uses the ECHAM4.6 model to simulate the possible mechanism of the interdecadal change through a control test and three sensitivity tests. A controlled trial is carried out using the observed climate monthly mean sea temperature field, and the three sensitivity tests are respectively The first phase forced the tropical India ocean warming (TIO), the second phase forced the central Pacific warming (CP) and the tropical India and the central Pacific Ocean heating (TIO-CP). The results showed that the first and second stages were mainly due to the second stage in the 8-10 month India ocean temperature obviously warmer than the first stage, and the contrast second. The change of stage and third stage is due to the obvious warming of SST in the equatorial central Pacific in the third phase and 8-10 months.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P444;P732

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