【摘要】：位于海南島東部的瓊東上升流是南海北部陸架上升流系統(tǒng)的強(qiáng)中心之一,其溫鹽特征的變化對(duì)局地生態(tài)、漁業(yè)、氣候等有直接影響。南海和西太平洋生成的熱帶氣旋在移動(dòng)過(guò)程中常與瓊東上升流區(qū)不期而遇。探究熱帶氣旋對(duì)瓊東上升流的影響規(guī)律和機(jī)制,具有重要的科學(xué)意義和應(yīng)用價(jià)值。本文利用近30年的衛(wèi)星遙感資料和2013年現(xiàn)場(chǎng)觀測(cè)資料,對(duì)過(guò)境瓊東上升流區(qū)的熱帶氣旋引起的海表溫度(SST)和溫鹽結(jié)構(gòu)變化進(jìn)行分析。結(jié)果顯示,與開(kāi)闊大洋顯著不同,瓊東上升流區(qū)SST變化存在降溫、基本不變和降溫三種類型。1982-2011年過(guò)境瓊東上升流區(qū)的36例熱帶氣旋中,有為17例引起降溫、16例SST基本不變,3例引起升溫。平均升溫2.1oC大于平均降溫-1.5oC。SST變化與熱帶氣旋要素的統(tǒng)計(jì)關(guān)系顯示,與氣旋過(guò)境時(shí)長(zhǎng)相比,熱帶氣旋強(qiáng)度和入射角度對(duì)SST變化幅度影響更大。2013年8月熱帶氣旋“飛燕”過(guò)境瓊東上升流區(qū),上升流區(qū)SST上升,尤其是氣旋路徑右側(cè)上升流中心升溫幅度最大為1oC。氣旋前后現(xiàn)場(chǎng)觀測(cè)斷面的對(duì)比分析顯示,瓊東上升流區(qū)整個(gè)水層的溫鹽特性和層結(jié)結(jié)構(gòu)發(fā)生顯著變化。等溫線和等密線的向岸爬升和躍層深度向岸變淺在熱帶氣旋過(guò)境后消失。近岸區(qū)表層增溫且混合層和躍層顯著加深(平均15 m),近岸淺層整層升溫。離岸區(qū)表層溫度降低,混合層和躍層深度基本不變。整個(gè)斷面,躍層基本水平分布于20 30 m水層,并出現(xiàn)30 40 km的次中尺度波動(dòng)信號(hào)。對(duì)瓊東上升流區(qū)溫度變化機(jī)制的分析發(fā)現(xiàn),熱帶氣旋在外海引起的非線性海面孤立波向近岸的熱輸送是SST升溫的主要機(jī)制,觀測(cè)的SST升溫與熱帶氣旋入射角度的關(guān)系與理論結(jié)果吻合。熱帶氣旋過(guò)境瓊東上升流區(qū)引起的溫度變化特征取決于熱帶氣旋引起的局地垂向?qū)α骱突旌线^(guò)程的熱損失、局地風(fēng)場(chǎng)驅(qū)動(dòng)的近岸Ekman輸送和外海非線性孤立波向岸熱輸?shù)南鄬?duì)大小。
[Abstract]:The Qiongdong upwelling in the eastern part of Hainan Island is one of the strong centers of the upwelling system in the northern shelf of the South China Sea. The variation of its temperature and salt characteristics has a direct influence on the local ecology, fishery and climate. The tropical cyclones formed in the South China Sea and the Western Pacific are often encountered in the eastward upwelling zone. It is of great scientific significance and practical value to study the influence of tropical cyclones on the upwelling of eastern Qiongdong. Based on the satellite remote sensing data of nearly 30 years and the field observation data in 2013, the changes of sea surface temperature (SST) and temperature and salt structure caused by tropical cyclones in the upwelling area of eastern Hainan are analyzed in this paper. The results show that, in contrast to the open ocean, there are three types of SST variation in the East Hainan upwelling zone: cooling, basically unchanged and cooling. From 1982 to 2011, 36 cases of tropical cyclones in the East Hainan upwelling zone were transited. There were 17 cases of hypothermia, 16 cases of SST remained unchanged, 3 cases of temperature. The statistical relationship between mean warming 2.1oC and tropical cyclone elements is greater than that of average cooling 1.5oC.SST, which is compared with the cyclones transit time. The intensity and incidence angle of tropical cyclone have more influence on the range of SST. In August 2013, tropical cyclone "Feiyan" transited the upwelling area of Qiongdong, and the upwelling area SST increased, especially the upwelling center on the right side of the cyclone path was the largest one. The comparative analysis of the observed sections before and after the cyclone shows that the characteristics of temperature and salt and the stratification structure of the whole water layer in the upwelling area of east Qiongdong have changed significantly. The isotherm and isodilinear climbing along the shore and the depth of the cline shallowing disappear after the transit of the tropical cyclone. The surface layer of the inshore area is heated and the mixing layer and cline layer are obviously deepened (average 15 m), the whole shallow layer of the nearshore layer is warming up.) The surface temperature of the offshore zone decreases and the mixing and cline depths remain unchanged. In the whole section, the basic horizontal distribution of the cline is in the water layer of 20 ~ 30 m, and the sub-mesoscale wave signal of 30 ~ 40 km appears. Based on the analysis of the temperature variation mechanism in the upwelling zone of eastern Hainan, it is found that the thermal transport of nonlinear sea solitary waves to the shore caused by tropical cyclones in the open sea is the main mechanism of SST warming. The relationship between the observed SST temperature and the incidence angle of tropical cyclone is in agreement with the theoretical results. The characteristics of temperature variation caused by tropical cyclones passing through the upwelling zone of eastern Hainan depend on the local heat loss of vertical convection and mixing process caused by tropical cyclones. The relative magnitude of the near-shore Ekman transport driven by local wind field and the offshore nonlinear solitary wave to shore heat transport.
【學(xué)位授予單位】：廣東海洋大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：P732.6

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本文編號(hào)：2268498