台风“Chanchu”变性过程位涡及锋生特征分析
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摘要
利用非静力中尺度WRF模式输出的0601号"Chanchu"台风模拟资料分析了台风变性过程中的结构演变特征,并从位涡的角度,利用湿位涡方程对"Chanchu"变性过程中强度减弱但却能引发强风暴雨的原因进行了探讨。分析表明:台风在变性过程中,尺度逐渐增大并与东移南下的高空槽不断接近,在与高空槽相互作用之前,台风眼壁及外围雨带雷达回波减弱,最大风速减小,最大风速半径圈向外拓展;高低层位涡相接之后,由于高层正位涡的下传携带冷空气侵入台风,在低层锋区上诱发出气旋性环流,进而重新引发强对流,并在角动量的输送作用下,台风外围环流风速再次增大。变性后高空槽和台风在位相上仍有一定距离,高空槽仅与台风的外围环流相互作用,冷空气没有入侵台风内部,这是"Chanchu"没有重新加强的原因之一。利用锋生函数对引起锋生的各分量进行分析,结果显示非绝热加热是造成锋生的主要原因,散度和变形项的贡献次之,倾斜项对锋生几乎没有贡献。
This paper uses data from numerical simulations of the non-hydrostatic mesoscale model WRF on typhoon "Chanchu"(0601) to investigate the structural evolution characteristics of Extratropical Transition(ET), and uses the moist potential vorticity equation to discuss why weakening typhoon "Chanchu" can still cause heavy storm during ET from the perspective of Potential Vorticity(PV). The analysis shows that "Chanchu" gradually expands and becomes nearly collocated with the upper trough upstream moving southeasterly. Before the interaction between trough and typhoon, the maximum wind speed decreases and RMW expands outward, accompanied by the reduction of radar reflectivity of eyewall and outer rain bands. After the upper-level and lower-level PVs meet, the cyclonic circulation is induced in the front area of the lower layer due to incursion of cold air associated with downward transportation of positive-PV from upper-level, and then the deep convection is retriggered. Under the transportation effect of the angular momentum, the wind speed of peripheral circulation of typhoon increases once again. After ET, there is still a certain distance in phase between the trough and typhoon. The upper trough only interacts with peripheral circulation of the typhoon and the cold air fails to intrude into the TC inner area, which is one of the reasons why "Chanchu" does not reintensify. The contribution of the four contributing terms to frontogenesis is analyzed based on frontogenesis function, the result shows that the diabatic heating term is the main contributor to frontogenesis, followed by the divergence and deformation terms, while the tilting term is negligible.
This paper uses data from numerical simulations of the non-hydrostatic mesoscale model WRF on typhoon "Chanchu"(0601) to investigate the structural evolution characteristics of Extratropical Transition(ET), and uses the moist potential vorticity equation to discuss why weakening typhoon "Chanchu" can still cause heavy storm during ET from the perspective of Potential Vorticity(PV). The analysis shows that "Chanchu" gradually expands and becomes nearly collocated with the upper trough upstream moving southeasterly. Before the interaction between trough and typhoon, the maximum wind speed decreases and RMW expands outward, accompanied by the reduction of radar reflectivity of eyewall and outer rain bands. After the upper-level and lower-level PVs meet, the cyclonic circulation is induced in the front area of the lower layer due to incursion of cold air associated with downward transportation of positive-PV from upper-level, and then the deep convection is retriggered. Under the transportation effect of the angular momentum, the wind speed of peripheral circulation of typhoon increases once again. After ET, there is still a certain distance in phase between the trough and typhoon. The upper trough only interacts with peripheral circulation of the typhoon and the cold air fails to intrude into the TC inner area, which is one of the reasons why "Chanchu" does not reintensify. The contribution of the four contributing terms to frontogenesis is analyzed based on frontogenesis function, the result shows that the diabatic heating term is the main contributor to frontogenesis, followed by the divergence and deformation terms, while the tilting term is negligible.
引文
[1] Hart R E, Evans J L. A climatology of the extratropical transition of Atlantic tropical cyclones. J. Climate, 2001, 14(4): 546-564.
[2] Kofron D E, Ritchie E A, Tyo J S. Determination of a consistent time for the extratropical transition of tropical cyclones. Part I: examination of existing methods for finding “ET Time”. Mon. Wea. Rev., 2010, 138(12): 4328-4343.
[3] Evans J L, Hart R E. Objective indicators of the life cycle evolution of extratropical transition for Atlantic tropical cyclones. Mon. Wea. Rev., 2001, 131(5): 909-925.
[4] Klein P M, Harr P A, Elsberry R L. Extratropical transition of western North Pacific tropical cyclones: an overview and conceptual model of the transformation stage. Wea. Forecasting, 2000, 15(4): 373-395.
[5] Hart R E. A cyclone phase space derived from thermal wind and thermal asymmetry. Mon. Wea. Rev., 2003, 131(4): 585-616.
[6] Harr P A, Elsberry R L. Extratropical transition of tropical cyclones over the western North Pacific. Part I: evolution of structural characteristics during the transition process. Mon. Wea. Rev., 2000, 128(8): 2613-2633.
[7] Kofron D E, Ritchie E A, Tyo J S. Determination of a consistent time for the extratropical transition of tropical cyclones. Part II: potential vorticity metrics. Mon. Wea. Rev., 2010, 138(12): 4344-4361.
[8] 寿绍文. 位涡理论及其应用. 气象, 2010, 36(3): 9-18. SHOU Shaowen. Theory and application of potential vorticity. Meteorological Monthly (in Chinese), 2010, 36(3): 9-18.
[9] Bosart L F, Lackmann G M. Postlandfall tropical cyclone reintensification in a weakly baroclinic environment: a case study of hurricane David (September 1979). Mon. Wea. Rev., 1995, 123(11): 3268-3291.
[10] McTaggart-Cowan R, Gyakum J R, Yau M K. Sensitivity testing of extratropical transitions using potential vorticity inversions to modify initial conditions: hurricane earl case study. Mon. Wea. Rev., 2001, 129(7): 1617-1636.
[11] Thorncroft C, Jones S C. The extratropical transitions of hurricanes Felix and Iris in 1995. Mon. Wea. Rev., 2000, 128(4): 947-972.
[12] Atallah E H, Bosart L F. The extratropical transition and precipitation distribution of hurricane Floyd (1999). Mon. Wea. Rev., 2003, 131(6): 1063-1081.
[13] 王凯, 张雪婷, 王云峰, 等. 热带气旋的温带变性过程对中纬度下游环流的影响. 气象科学, 2014, 34(2): 179-186. WANG Kai, ZHANG Xueting, WANG Yunfeng, et al. Impact of extratropical transition of tropical cyclone on the mid-latitude downstream flow.Journal of the Meteorological Sciences (in Chinese), 2014, 34(2): 179-186.
[14] WANG Qian, LI Qingqing, FU Gang. Determining the extratropical transition onset and completion times of Typhoons Mindulle (2004) and Yagi (2006) using four methods. Wea. Forecasting, 2012, 27(6): 1394-1412.
[15] LI Qingqing, WANG Qian. Re-examination of the potential vorticity metrics for determining extratropical transition onset and completion times using high-resolution data. Acta Meteor. Sin., 2013, 27(4): 502-508.
[16] 曹楚, 王忠东, 刘峰, 等. 2013年“菲特”台风暴雨成因及湿位涡诊断分析. 气象与环境科学, 2016, 39(4): 86-92. CAO Chu, WANG Zhongdong, LIU Feng, et al. Diagnostic analysis of moist potential vorticity for heavy rain caused by “Fitow” (2013) Typhoon. Meteorological and Environmental Sciences (in Chinese), 2016, 39(4): 86-92.
[17] 陈德花, 寿绍文, 张玲, 等. “碧利斯”引发强降水过程的湿位涡诊断分析. 暴雨灾害, 2008, 27(1): 37-41. CHEN Dehua, SHOU Shaowen, ZHANG Ling, et al. Diagnostic analysis of moist potential vorticity for heavy rain caused by “Billis” Typhoon. Torrential Rain and Disasters (in Chinese), 2008, 27(1): 37-41.
[18] 杨博雷, 闵锦忠, 王仕奇, 等. 北京7.21暴雨低涡演变的湿位涡分析. 气象科学, 2016, 36(6): 721-731. YANG Bolei, MIN Jinzhong, WANG Shiqi, et al. Moist potential vorticity analysis of the mesoscale vortex in the heavy rainfall on July 21, 2012 of Beijing.Journal of the Meteorological Sciences (in Chinese), 2016, 36(6): 721-731.
[19] 韩桂荣, 何金海, 樊永富, 等. 变形场锋生对0108登陆台风温带变性和暴雨形成作用的诊断分析. 气象学报, 2005, 63(4): 468-476. HAN Guirong, HE Jinghai, FAN Yongfu, et al. The transfiguration frontogenesis analyses on 0108 landfall Typhoon extratropical transition and heavy rain structure. Acta Meteorologica Sinica (in Chinese), 2005, 63(4): 468-476.
[20] 雷小途, 汤杰. 锋生过程在台风变性再增强中的作用——0108台风"桃芝"模拟研究//国家973计划“台风登陆前后异常变化及机理研究”项目2009年度学术年会. 北京, 2010: 83-87. LEI Xiaotu, TANG Jie. The role of frontogenesis in post-extratropical Typhoon reintensification—a numerical study of Typhoon “Toraji” (0108)//973 Program of China Entitled “Unusual Variation of Landfalling Tropical Cyclones and Associated Physical Mechanisms” Academic Annual Conference of 2009 (in Chinese). Beijing, 2010: 83-87.
[21] Klein P M, Harr P A, Elsberry R L. Extratropical transition of western North Pacific tropical cyclones: midlatitude and tropical cyclone contributions to reintensification. Mon. Wea. Rev., 2002, 130(9): 2240-2259.
[22] 姜丽萍, 夏冠聪, 尤红, 等. “珍珠”台风强度及路径异常的分析. 台湾海峡, 2008, 27(1): 124-128. JIANG Liping, XIA Guancong, YOU Hong, et al.Analysis on the abnormal intention and track of typhoon “Chanchu”. Journal of Oceanography in Taiwan Strait (in Chinese), 2008, 27(1): 124-128.
[23] 曹美兰, 王坚侃, 陈梅汀. “珍珠”的定位定性误差和舟山大暴雨分析//中国气象学会2006年年会. 北京: 中国气象学会, 2006. CAO Meilan, WANG Jiankan, CHEN Meiting. Qualitative and positioning error of “Chanchu” and analysis of heavy rainfall in Zhoushan// Chinese Meteorological Society Annual Meeting of 2006. Beijing: Chinese Meteorological Society (in Chinese), 2006.
[24] 姜有山, 束宇, 李力, 等. 基于湿位涡和积雪效率的降雪预报技术探讨. 气象科学, 2017, 37(5): 659-665. JIANG Youshan, SHU Yu, LI Li, et al. Investigation on snowfall forecasting skills based on moist potential vorticity and efficiency of snow accumulation. Journal of the Meteorological Sciences (in Chinese), 2017,37(5): 659-665.
[25] Miller J E. On the concept of frontogenesis. J. Meteor., 1948, 5(4): 169-171.
[26] 吴国雄, 蔡雅萍, 唐晓菁. 湿位涡和倾斜涡度发展. 气象学报, 1995, 53(4): 387-405. WU Guoxiong, CAI Yaping, TANG Xiaojing. Moist potential vorticity and slantwise vorticity development. Acta Meteorologica Sinica (in Chinese), 1995, 53(4): 387-405.
[27] Shin J H, ZHANG Dalin. The impact of moist frontogenesis and tropopause undulation on the intensity, size, and structural changes of hurricane sandy (2012). J. Atmos. Sci., 2017, 74(3): 893-913.
[28] 李兆慧, 王东海, 王建捷, 等. 一次暴雪过程的锋生函数和急流—锋面次级环流分析. 高原气象, 2011, 30(6): 1505-1515. LI Zhaohui, WANG Donghai, WANG Jianjie, et al. Analysis on frontogenesis function and jet-front secondary circulation in a snowstorm process. Plateau Meteorology (in Chinese), 2011, 30(6): 1505-1515.
[29] 韩桂荣, 唐晓文, 魏建苏. 登陆台风变性发展与消亡的对比分析. 气象科学, 2007, 27(1): 35-41. HAN Guirong, TANG Xiaowen, WEI Jiansu. The extratropical transition analyses on two landfall Typhoons. Scientia Meteorologica Sinica (in Chinese), 2007, 27(1): 35-41.
[2] Kofron D E, Ritchie E A, Tyo J S. Determination of a consistent time for the extratropical transition of tropical cyclones. Part I: examination of existing methods for finding “ET Time”. Mon. Wea. Rev., 2010, 138(12): 4328-4343.
[3] Evans J L, Hart R E. Objective indicators of the life cycle evolution of extratropical transition for Atlantic tropical cyclones. Mon. Wea. Rev., 2001, 131(5): 909-925.
[4] Klein P M, Harr P A, Elsberry R L. Extratropical transition of western North Pacific tropical cyclones: an overview and conceptual model of the transformation stage. Wea. Forecasting, 2000, 15(4): 373-395.
[5] Hart R E. A cyclone phase space derived from thermal wind and thermal asymmetry. Mon. Wea. Rev., 2003, 131(4): 585-616.
[6] Harr P A, Elsberry R L. Extratropical transition of tropical cyclones over the western North Pacific. Part I: evolution of structural characteristics during the transition process. Mon. Wea. Rev., 2000, 128(8): 2613-2633.
[7] Kofron D E, Ritchie E A, Tyo J S. Determination of a consistent time for the extratropical transition of tropical cyclones. Part II: potential vorticity metrics. Mon. Wea. Rev., 2010, 138(12): 4344-4361.
[8] 寿绍文. 位涡理论及其应用. 气象, 2010, 36(3): 9-18. SHOU Shaowen. Theory and application of potential vorticity. Meteorological Monthly (in Chinese), 2010, 36(3): 9-18.
[9] Bosart L F, Lackmann G M. Postlandfall tropical cyclone reintensification in a weakly baroclinic environment: a case study of hurricane David (September 1979). Mon. Wea. Rev., 1995, 123(11): 3268-3291.
[10] McTaggart-Cowan R, Gyakum J R, Yau M K. Sensitivity testing of extratropical transitions using potential vorticity inversions to modify initial conditions: hurricane earl case study. Mon. Wea. Rev., 2001, 129(7): 1617-1636.
[11] Thorncroft C, Jones S C. The extratropical transitions of hurricanes Felix and Iris in 1995. Mon. Wea. Rev., 2000, 128(4): 947-972.
[12] Atallah E H, Bosart L F. The extratropical transition and precipitation distribution of hurricane Floyd (1999). Mon. Wea. Rev., 2003, 131(6): 1063-1081.
[13] 王凯, 张雪婷, 王云峰, 等. 热带气旋的温带变性过程对中纬度下游环流的影响. 气象科学, 2014, 34(2): 179-186. WANG Kai, ZHANG Xueting, WANG Yunfeng, et al. Impact of extratropical transition of tropical cyclone on the mid-latitude downstream flow.Journal of the Meteorological Sciences (in Chinese), 2014, 34(2): 179-186.
[14] WANG Qian, LI Qingqing, FU Gang. Determining the extratropical transition onset and completion times of Typhoons Mindulle (2004) and Yagi (2006) using four methods. Wea. Forecasting, 2012, 27(6): 1394-1412.
[15] LI Qingqing, WANG Qian. Re-examination of the potential vorticity metrics for determining extratropical transition onset and completion times using high-resolution data. Acta Meteor. Sin., 2013, 27(4): 502-508.
[16] 曹楚, 王忠东, 刘峰, 等. 2013年“菲特”台风暴雨成因及湿位涡诊断分析. 气象与环境科学, 2016, 39(4): 86-92. CAO Chu, WANG Zhongdong, LIU Feng, et al. Diagnostic analysis of moist potential vorticity for heavy rain caused by “Fitow” (2013) Typhoon. Meteorological and Environmental Sciences (in Chinese), 2016, 39(4): 86-92.
[17] 陈德花, 寿绍文, 张玲, 等. “碧利斯”引发强降水过程的湿位涡诊断分析. 暴雨灾害, 2008, 27(1): 37-41. CHEN Dehua, SHOU Shaowen, ZHANG Ling, et al. Diagnostic analysis of moist potential vorticity for heavy rain caused by “Billis” Typhoon. Torrential Rain and Disasters (in Chinese), 2008, 27(1): 37-41.
[18] 杨博雷, 闵锦忠, 王仕奇, 等. 北京7.21暴雨低涡演变的湿位涡分析. 气象科学, 2016, 36(6): 721-731. YANG Bolei, MIN Jinzhong, WANG Shiqi, et al. Moist potential vorticity analysis of the mesoscale vortex in the heavy rainfall on July 21, 2012 of Beijing.Journal of the Meteorological Sciences (in Chinese), 2016, 36(6): 721-731.
[19] 韩桂荣, 何金海, 樊永富, 等. 变形场锋生对0108登陆台风温带变性和暴雨形成作用的诊断分析. 气象学报, 2005, 63(4): 468-476. HAN Guirong, HE Jinghai, FAN Yongfu, et al. The transfiguration frontogenesis analyses on 0108 landfall Typhoon extratropical transition and heavy rain structure. Acta Meteorologica Sinica (in Chinese), 2005, 63(4): 468-476.
[20] 雷小途, 汤杰. 锋生过程在台风变性再增强中的作用——0108台风"桃芝"模拟研究//国家973计划“台风登陆前后异常变化及机理研究”项目2009年度学术年会. 北京, 2010: 83-87. LEI Xiaotu, TANG Jie. The role of frontogenesis in post-extratropical Typhoon reintensification—a numerical study of Typhoon “Toraji” (0108)//973 Program of China Entitled “Unusual Variation of Landfalling Tropical Cyclones and Associated Physical Mechanisms” Academic Annual Conference of 2009 (in Chinese). Beijing, 2010: 83-87.
[21] Klein P M, Harr P A, Elsberry R L. Extratropical transition of western North Pacific tropical cyclones: midlatitude and tropical cyclone contributions to reintensification. Mon. Wea. Rev., 2002, 130(9): 2240-2259.
[22] 姜丽萍, 夏冠聪, 尤红, 等. “珍珠”台风强度及路径异常的分析. 台湾海峡, 2008, 27(1): 124-128. JIANG Liping, XIA Guancong, YOU Hong, et al.Analysis on the abnormal intention and track of typhoon “Chanchu”. Journal of Oceanography in Taiwan Strait (in Chinese), 2008, 27(1): 124-128.
[23] 曹美兰, 王坚侃, 陈梅汀. “珍珠”的定位定性误差和舟山大暴雨分析//中国气象学会2006年年会. 北京: 中国气象学会, 2006. CAO Meilan, WANG Jiankan, CHEN Meiting. Qualitative and positioning error of “Chanchu” and analysis of heavy rainfall in Zhoushan// Chinese Meteorological Society Annual Meeting of 2006. Beijing: Chinese Meteorological Society (in Chinese), 2006.
[24] 姜有山, 束宇, 李力, 等. 基于湿位涡和积雪效率的降雪预报技术探讨. 气象科学, 2017, 37(5): 659-665. JIANG Youshan, SHU Yu, LI Li, et al. Investigation on snowfall forecasting skills based on moist potential vorticity and efficiency of snow accumulation. Journal of the Meteorological Sciences (in Chinese), 2017,37(5): 659-665.
[25] Miller J E. On the concept of frontogenesis. J. Meteor., 1948, 5(4): 169-171.
[26] 吴国雄, 蔡雅萍, 唐晓菁. 湿位涡和倾斜涡度发展. 气象学报, 1995, 53(4): 387-405. WU Guoxiong, CAI Yaping, TANG Xiaojing. Moist potential vorticity and slantwise vorticity development. Acta Meteorologica Sinica (in Chinese), 1995, 53(4): 387-405.
[27] Shin J H, ZHANG Dalin. The impact of moist frontogenesis and tropopause undulation on the intensity, size, and structural changes of hurricane sandy (2012). J. Atmos. Sci., 2017, 74(3): 893-913.
[28] 李兆慧, 王东海, 王建捷, 等. 一次暴雪过程的锋生函数和急流—锋面次级环流分析. 高原气象, 2011, 30(6): 1505-1515. LI Zhaohui, WANG Donghai, WANG Jianjie, et al. Analysis on frontogenesis function and jet-front secondary circulation in a snowstorm process. Plateau Meteorology (in Chinese), 2011, 30(6): 1505-1515.
[29] 韩桂荣, 唐晓文, 魏建苏. 登陆台风变性发展与消亡的对比分析. 气象科学, 2007, 27(1): 35-41. HAN Guirong, TANG Xiaowen, WEI Jiansu. The extratropical transition analyses on two landfall Typhoons. Scientia Meteorologica Sinica (in Chinese), 2007, 27(1): 35-41.