台湾岛附近台风异常路径特征及其预报不确定性的初步研究

发布时间：2018-01-16 00:32

本文关键词：台湾岛附近台风异常路径特征及其预报不确定性的初步研究　出处：《中国气象科学研究院》2017年硕士论文　论文类型：学位论文

【摘要】：目前热带气旋(Tropical Cyclone,TC)路径预报能力已有很大提高,但异常路径的预报能力仍然比较薄弱。我国台湾岛附近区域地形复杂,TC异常路径频发。论文首先对1949-2014年台湾岛附近区域(116°E-126°E,19°N-29°N)内530个TC的运动特征进行统计分析。其次采用个例诊断和集合天气学分析方法,讨论台风Morakot(0908)异常路径成因及其预报不确定性。最后通过数值敏感性试验,探讨台湾岛地形对Morakot异常路径的影响。统计表明,台湾岛附近区域TC右折频次比左折多约10%,其中岛屿西北部至台湾海峡北部右折频次明显多于左折,而台湾岛东岸沿海则是左折多于右折。TC路径大角度的异常偏折容易出现在台湾岛东北侧、西南侧及台湾海峡南端。异常加速(减速)主要出现在台湾岛东岸(海峡南部)。约33%TC经过台湾岛区域时伴随次生低压(secondary low pressure center,SC)。SC可出现在中央山脉东西两侧,最容易出现在台湾岛西北方。TC中心与其次生低压一般各分布于中央山脉异侧,少数在同侧。SC代替原台风中心形成不连续路径的TC个例占总登陆台湾岛TC总数的36%。利用中尺度数值模式WRF模拟结果,诊断分析台风Morakot(0908)缓慢过岛的不连续路径发生原因,发现除西太平洋副热带高压(副高)影响及双台风效应外,过岛台风的结构变化是一个重要原因。Morakot异常路径与台湾地形附近台风环流内SC的发生发展有关。SC替代台风中心形成不连续路径的过程,是台风低层环流从分裂到重组、台风正涡度柱从垂直到倾斜再恢复垂直的缓慢变化过程,增加了Morakot在台湾岛附近的活动时间。对ECMWF发布的TC路径集合预报结果进行分析,发现对Morakot过台湾岛缓慢西行的不连续路径,不论早期远离台湾岛还是临近登陆前的预报结果都具有较大的不确定性。利用集合天气学分析方法分析集合成员预报成功和失败的原因,结果表明,早期TC路径预报误差主要来自于模式对副高、西南气流、双台风等大尺度环境场描述的差异,导致TC西行过岛和登岛前北折的路径预报分歧。而后期临近登陆时环境引导气流较弱,地形与TC环流相互作用产生的SC活动是路径预报成功与否的关键因子。成功预报集合成员SC发展更强,与原台风中心距离更近,最终代替TC中心,导致西行过岛的不连续路径。而失败预报集合成员的SC发展较弱,且距台风中心较远,未能代替TC中心产生西行过岛的不连续路径,而是在台湾岛东部海域转向北上。进一步利用中尺度数值模式WRF开展不同高度台湾岛地形对Morakot异常路径影响的敏感性试验。发现地形作用使台风移向容易偏折,移速波动大,过岛时间长,并可激发次生低压,导致台风不连续路径。当去除台湾地形,台风路径摆动小,过岛时间短,无次生生低压和不连续路径发生。
[Abstract]:The tropical cyclone (Tropical Cyclone, TC) path prediction capability has been greatly improved, but the prediction ability of abnormal path is still relatively weak. Near Taiwan island terrain in China is complex, frequent TC abnormal path. Firstly, 1949-2014 near the island of Taiwan region (116 degrees E-126 degrees E, 19 degrees N-29 degrees N) motion feature in 530 TC were analyzed. The diagnosis of case and collection of synoptic analysis methods, the discussion of typhoon Morakot (0908) abnormal path causes and forecast uncertainty. Finally through numerical sensitivity experiments on Taiwan island shape effect on Morakot abnormal path. The statistics show that the Taiwan island region near the TC right fold frequency ratio left about 10% fold, the northwest of the island to the northern Taiwan Strait right fold frequency significantly more than the left fold, and the east coast of Taiwan coastal is left off more than the right folding.TC path of large angle deflection is prone to abnormal In the island of Taiwan northeast, southwest and south of the Taiwan Strait. The abnormal acceleration (deceleration) occurred mainly in the east coast of Taiwan (the South). About 33%TC through the Taiwan island area with secondary low (secondary low pressure center, SC.SC) can be seen in the two side of the central mountain range, most likely to occur in the island of Taiwan North West.TC center and the secondary low general distribution in the central mountain range from side to side, a few on the same side of.SC instead of the original typhoon center form a case of the TC continuous path of the total land in Taiwan island TC 36%. of the total number of the mesoscale numerical model WRF simulation results, the diagnostic analysis of typhoon Morakot (0908) is not a continuous path slow island the causes, in addition to the Western Pacific subtropical high (SH) and double typhoon effect, the structure change of typhoon is one of the important reasons of.Morakot abnormal path and Taiwan terrain near the typhoon circulation in SC Discontinuous path formation related to the occurrence and development of.SC instead of the center of typhoon, the typhoon low level circulation from fragmentation to restructuring, the typhoon positive vorticity column from vertical to tilt to the slow recovery of the change process of vertical, increased Morakot in Taiwan near the island of time. The TC path ECMWF release of the ensemble results are analyzed. Find a continuous path on Morakot island of Taiwan slowly westward, it has greater uncertainty from early or near the island of Taiwan before landing the prediction results. Using synoptic analysis set set of reasons, members of forecasting the success and failure of the results show that early TC path prediction error mainly comes from the mode of the subtropical high. The southwest airflow, two typhoons and other large scale environmental field description of differences, resulting in TC over the island and landed westbound route forecast North off the island. The differences and close to the late landing environment guide The airflow is weak, terrain and TC circulation caused by the interaction of SC activity is the key factor for the success of the path prediction. The successful prediction of the ensemble members SC to develop stronger, and the distance from the original typhoon center near, to eventually replace the TC center, leading to the continuous path passing through the island. Westbound failed ensemble members of the SC development is weak, and far away from the typhoon center, not a continuous path to replace the TC generated in the center of westbound passing through the island, but in the eastern waters of Taiwan island to the north. Further sensitivity test using the mesoscale numerical model WRF to carry out the effect of different height of the Taiwan topography of Morakot abnormal path. The effect of terrain to the typhoon moving to find easy deflection, speed fluctuation the big island, too long time, and can stimulate secondary low, resulting in a typhoon discontinuous path. When removing the terrain of Taiwan, the typhoon path swing small island too short time, no secondary depression and discontinuous path development Students.

【学位授予单位】：中国气象科学研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P444;P457.8

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