中國南方持續(xù)性低溫雨雪冰凍事件環(huán)流分型特征
發(fā)布時間：2018-09-11 17:52
【摘要】：針對1980年以來南方持續(xù)性低溫雨雪冰凍事件的8次過程及其相關(guān)降水溫度觀測資料和大氣環(huán)流再分析資料,利用客觀分析方法進行環(huán)流分型并分析其關(guān)鍵分型特征。結(jié)果表明,我國南方持續(xù)性低溫雨雪冰凍事件至少有兩種大尺度環(huán)流分型,具體表現(xiàn)為:1)單阻型:500 hPa阻塞高壓位于貝加爾湖地區(qū),東亞大槽位置偏東,高度場上中亞以及我國大部分地區(qū)以負異常為主,事件極有可能發(fā)生在AO正位相背景下;高層(200hPa)副熱帶急流位于青藏高原西側(cè)部分異常增強;低層(850 hPa)冷空氣經(jīng)我國東北部向西南方向輸送;低層(850 hPa)水汽輸送主要為兩條,分別為經(jīng)孟加拉灣的西南低空急流和來自南海的偏南氣流;多數(shù)個例對流層低層具有逆溫結(jié)構(gòu);2)雙阻型:500 hPa阻塞高壓位于烏拉爾山地區(qū)和鄂霍茨克海地區(qū),東亞大槽比單阻型事件期間的東亞大槽強度更強,位置偏西,極地位勢高度場主要處于正異常,事件多半可能發(fā)生在AO負位相背景下;高層(200 hPa)副熱帶急流主要在東亞中緯度區(qū)域異常增強,并且急流正異常中心相較于單阻型更偏北;低層(850 hPa)冷空氣經(jīng)貝加爾湖南下影響我國;低層(850 hPa)水汽輸送主要為西南低空急流;對流層下層大氣沒有明顯逆溫層。此外,通過對事件期間行星尺度羅斯貝波能量頻散診斷分析,揭示了行星尺度羅斯貝波能量頻散對于事件期間大尺度異常環(huán)流的穩(wěn)定維持以及南支槽的活動有著重要作用。2016年1月21日至25日,我國大部分地區(qū)遭受強寒潮事件。此次大范圍強寒潮事件發(fā)生較快,持續(xù)時間短。從大尺度環(huán)流背景角度分析此次事件的特征及成因,并與2008年持續(xù)性低溫雨雪冰凍事件作比較,經(jīng)過研究發(fā)現(xiàn):1)阻塞高壓區(qū)域有較強的能量頻散,而其上游并未有明顯能量輸送到阻塞區(qū)域,從而使阻塞高壓演變快速并崩潰,而2008年持續(xù)性低溫雨雪冰凍雪事件則是由于阻塞區(qū)域上游不斷有能量輸送至阻塞區(qū),使得阻塞高壓不斷維持,形成穩(wěn)定的阻塞形勢;2)地面西伯利亞高壓比2008年持續(xù)性低溫雨雪冰凍事件異常偏強,冷空氣也異常偏強,不利于降水的發(fā)生;3)中低緯度低槽系統(tǒng)不活躍,使得水汽輸送較弱,而2008年中低緯度低槽系統(tǒng)較強且活躍,為2008年事件提供充足的水汽;4)西太平洋副熱帶高壓相較于2008年事件期間位置偏東偏南,自南海水汽輸送較弱;5)冷空氣路徑與雙阻型持續(xù)性低溫雨雪冰凍事件相同。
[Abstract]:Based on the 8 processes of the continuous low temperature rain and snow freezing events in southern China since 1980 and the related precipitation temperature observation data and the atmospheric circulation reanalysis data, the circulation classification and its key classification characteristics are analyzed by objective analysis method. The results show that there are at least two types of large-scale circulation patterns for the persistent low temperature, rain and snow freezing events in southern China, which are manifested as: 1) the single resistance type of the 500 hPa blocking high is located in Baikal Lake region, and the East Asian trough is located eastward. In Central Asia and in most parts of China, the events may occur in the background of AO positive phase, the 200hPa subtropical jet is located in the west of Qinghai-Xizang Plateau, and the subtropical jet is enhanced in the west of Qinghai-Xizang Plateau. The cold air in the lower layer (850 hPa) is transported to the southwest through the northeast of China, and the vapor transport in the lower layer (850 hPa) is mainly in the southwest of the Bay of Bengal and the southerly stream from the South China Sea. In most cases, the tropospheric lower layer has a temperature inversion structure 2) the double resistance type hPa blocking high is located in the Ural Mountains and the Okhotsk Sea. The East Asian trough is stronger in intensity and westward than the East Asian trough during the single resistive event. The polar geopotential height field is mainly in positive anomaly, most of the events may take place in the AO negative background, the upper (200 hPa) subtropical jet is mainly anomalous in the mid-latitude region of East Asia, and the center of the positive anomaly of the jet is farther north than that of the single-resistive type. The cold air in the lower layer (850 hPa) affects China south of Baikal Lake, the vapor transport in the lower layer (850 hPa) is mainly in the southwest low level jet stream, and there is no obvious inversion layer in the lower troposphere atmosphere. In addition, through the diagnosis and analysis of the energy dispersion of the planetary scale Rossberg wave during the event, It is revealed that the energy dispersion of the planetary Rossby wave plays an important role in maintaining the large scale anomalous circulation and the activity of the southern branch trough during the event. From January 21 to 25, 2016, most areas of China suffered from strong cold wave events. The large-scale strong cold wave events occurred quickly, the duration of a short period. The characteristics and causes of the event are analyzed from the point of view of large-scale circulation background, and compared with the persistent low temperature, rain, snow and freezing events in 2008. It is found that there is a strong energy dispersion in the blocking high pressure region of 1: 1. However, there is no obvious energy flowing upstream to the blocking area, which causes the blocking high to evolve rapidly and collapses. However, the persistent low temperature, rain, snow and frozen snow events in 2008 are due to the continuous energy transfer from the upstream of the blocking area to the blocking area. This makes the blocking high constantly maintained and forms a stable blocking situation. 2) the Siberian high on the ground is unusually stronger than the persistent low temperature, rain, snow and freezing events in 2008, and the cold air is also unusually strong. The low trough system in middle and low latitudes is not active, which makes the water vapor transport weaker, while in 2008, the low trough system in middle latitude and low latitude is stronger and more active. To provide sufficient water vapor for the 2008 event) the position of the Western Pacific subtropical high is eastward and southward during the 2008 event, and the water vapor transport from the South China Sea is weaker than that of the South China Sea. 5) the cold air path is the same as the double resistive persistent low temperature rain and snow freezing event.
【學位授予單位】：中國氣象科學研究院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P434;P429
[Abstract]:Based on the 8 processes of the continuous low temperature rain and snow freezing events in southern China since 1980 and the related precipitation temperature observation data and the atmospheric circulation reanalysis data, the circulation classification and its key classification characteristics are analyzed by objective analysis method. The results show that there are at least two types of large-scale circulation patterns for the persistent low temperature, rain and snow freezing events in southern China, which are manifested as: 1) the single resistance type of the 500 hPa blocking high is located in Baikal Lake region, and the East Asian trough is located eastward. In Central Asia and in most parts of China, the events may occur in the background of AO positive phase, the 200hPa subtropical jet is located in the west of Qinghai-Xizang Plateau, and the subtropical jet is enhanced in the west of Qinghai-Xizang Plateau. The cold air in the lower layer (850 hPa) is transported to the southwest through the northeast of China, and the vapor transport in the lower layer (850 hPa) is mainly in the southwest of the Bay of Bengal and the southerly stream from the South China Sea. In most cases, the tropospheric lower layer has a temperature inversion structure 2) the double resistance type hPa blocking high is located in the Ural Mountains and the Okhotsk Sea. The East Asian trough is stronger in intensity and westward than the East Asian trough during the single resistive event. The polar geopotential height field is mainly in positive anomaly, most of the events may take place in the AO negative background, the upper (200 hPa) subtropical jet is mainly anomalous in the mid-latitude region of East Asia, and the center of the positive anomaly of the jet is farther north than that of the single-resistive type. The cold air in the lower layer (850 hPa) affects China south of Baikal Lake, the vapor transport in the lower layer (850 hPa) is mainly in the southwest low level jet stream, and there is no obvious inversion layer in the lower troposphere atmosphere. In addition, through the diagnosis and analysis of the energy dispersion of the planetary scale Rossberg wave during the event, It is revealed that the energy dispersion of the planetary Rossby wave plays an important role in maintaining the large scale anomalous circulation and the activity of the southern branch trough during the event. From January 21 to 25, 2016, most areas of China suffered from strong cold wave events. The large-scale strong cold wave events occurred quickly, the duration of a short period. The characteristics and causes of the event are analyzed from the point of view of large-scale circulation background, and compared with the persistent low temperature, rain, snow and freezing events in 2008. It is found that there is a strong energy dispersion in the blocking high pressure region of 1: 1. However, there is no obvious energy flowing upstream to the blocking area, which causes the blocking high to evolve rapidly and collapses. However, the persistent low temperature, rain, snow and frozen snow events in 2008 are due to the continuous energy transfer from the upstream of the blocking area to the blocking area. This makes the blocking high constantly maintained and forms a stable blocking situation. 2) the Siberian high on the ground is unusually stronger than the persistent low temperature, rain, snow and freezing events in 2008, and the cold air is also unusually strong. The low trough system in middle and low latitudes is not active, which makes the water vapor transport weaker, while in 2008, the low trough system in middle latitude and low latitude is stronger and more active. To provide sufficient water vapor for the 2008 event) the position of the Western Pacific subtropical high is eastward and southward during the 2008 event, and the water vapor transport from the South China Sea is weaker than that of the South China Sea. 5) the cold air path is the same as the double resistive persistent low temperature rain and snow freezing event.
【學位授予單位】：中國氣象科學研究院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P434;P429
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