【作者】 吴磊；

【导师】 谈哲敏；

【作者基本信息】 南京大学 ， 大气科学， 2013， 硕士

【摘要】 本文利用2001-2011年西北太平洋的观测资料,针对至少达到热带风暴强度的热带气旋(TCs),研究了TC尺度的特征。在这里,TC尺度包括内核尺度和外围尺度,它们分别用最大风速半径(RMW)和方位角平均的8级风圈半径(17.5m s-1风速半径；R17)来定义。通过分析TC尺度的统计特征,研究发现：(1)RMW主要集中在20-80km,它的平均值为47.8km；R17主要集中在80-280km,它的平均值为194.2km。(2)对2004-2011年西北太平洋和北大西洋的R17进行了比较,验证了西北太平洋TCs的平均R17比北大西洋TCs的大。(3)平均的RMW在1月最大,之后随月份增加而趋向于减小；平均的R17在10月最大,2月最小。(4)平均RMW的最小值(20-40km)主要位于台湾近海,而平均R17的最大值(大于250km)主要位于日本西南部和中国黄海、渤海。同时本文研究了TC尺度和TC强度的关系,结果发现：(1)随着TC强度的增大,RMW趋向于减小,R17趋向于增大。(2)通过对所有TC生命期中的尺度和强度的合成分析,发现在TC的发展(减弱)期,RMW以减小(增大)为主,R17以增大(减小)为主。(3)在TC的减弱期,相比于TC强度,R17更容易受到环境因子的作用。(4)快速增强(RI)过程和不同强度类型都容易影响RMW,而不容易影响R17。本文进一步分析了TC尺度和环境因子的关系。在这里,环境因子包括热力学因子(海表面温度和出流层温度)、动力学因子(移动速度和垂直风切)和相对湿度。本文还引入了新的经验最大可能强度(MPInew),它综合考虑了影响TC的热力学因子和动力学因子。结果发现：(1)热力学因子对TC尺度几乎没有影响。(2)动力学因子对R17的分组前90%的样本具有负效应,但是对RMW几乎没有影响。(3)MPInew对R17的分组前90%的样本具有正效应,但是对RMW几乎没有影响,这验证了热力学因子和动力学因子对TC尺度的影响有限。(4)相对湿度是一个很重要的环境因子,它对R17的分组前50%的样本具有正效应,但是它对RMW几乎没有影响。更多还原

【Abstract】 The observations of tropical cyclones (TCs) with at least tropical storm intensity during2001-2011over the western North Pacific are used to study the characteristics of TC size. In this study, the TC size contains inner-core and outer size, which are defined respectively as the radius of maximum wind (RMW) and the azimuthally averaged radius of gale-force wind (R17).The statistical characteristics of TC size are investigated.(1) The RMW distribution mostly ranges from20to80km and the mean RMW is47.8km, while the R17distribution mostly ranges from80to280km and the mean R17is194.2km.(2) By comparing the R17of the TCs between the western North Pacific and the North Atlantic during2004-2011, we confirm that the mean R17in the western North Pacific is larger than that in the North Atlantic.(3) The mean RMW in January is largest and then tends to decrease with month; the mean R17in October is largest and is smallest in February.(4) The smallest mean RMW (20-40km) is mostly located in the coastal waters of Taiwan, while the largest mean R17(more than250km) mostly lies in the southwest part of Japan and the Yellow Sea and Bohai Sea in China.Meanwhile, the relationship between TC size and TC intensity is studied.(1) When the TC intensity increases, the RMW tends to decrease but the R17tends to increase.(2) Comparison of the size and intensity of all TCs during their lifetime demonstrates that in the developing (weakening) stage of the TC, the RMW mostly decreases (increases) and the R17mostly increases (decreases).(3) In the developing stage of the TC, the R17is more easily affected by environmental factors than TC intensity.(4) Rapid intensification (RI) process and different intensity categories of the TC both easily affect the RMW, but they don’t easily influence the R17. Further, the relationship between TC size and environmental factors are also studied. In this study, the environmental factors include the thermodynamic factors (sea surface temperature and outflow temperature), the dynamical factors (translational speed and vertical wind shear) and the relative humidity. This paper also brings in the new empirical maximum potential intensity (MPInew) which incorporates the thermodynamic and dynamical factors of the TC. The finds are summarized as follows.(1) The thermodynamic factors hardly affect TC size.(2) The dynamical factors are negative to top90%grouped samples of the R17, but it hardly affects the RMW.(3) The MPInew are positive to top90%grouped samples of the R17, but it hardly affects the RMW, which confirms that the thermodynamic and dynamical factors have limited effect on TC size.(4) The relative humidity is a very important environmental factor and is positive to top50%grouped samples of the R17, but it hardly affects the RMW.更多还原