【摘要】：在全球氣候變化背景下,研究新疆地區(qū)降水變化的區(qū)域特征和影響降水的天氣形勢(shì),具有重要的科學(xué)和社會(huì)意義。本文選取新疆47個(gè)氣象站點(diǎn)1961-2013年的逐日降水資料,分析了新疆降水的時(shí)空分布演變特征,并利用EOF、REOF方法對(duì)新疆夏季降水進(jìn)行氣候分區(qū)。結(jié)果表明:新疆地區(qū)1961-2013年降水量呈現(xiàn)出持續(xù)增長(zhǎng)的趨勢(shì),1987年后進(jìn)入降水偏多期。一年中,夏季是對(duì)新疆全年降水量貢獻(xiàn)最大的季節(jié),主導(dǎo)了全年降水量的空間分布及全年降水的變化趨勢(shì)。新疆年降水量呈現(xiàn)北多南少,全疆降水量上升的趨勢(shì),西北部增長(zhǎng)較多。EOF的四個(gè)模態(tài)體現(xiàn)了全疆夏季降水變化的一致性,天山山脈的阻擋造成了南、北疆的變化差異,新疆東部與西部,中部天山山區(qū)及附近與其他地區(qū)夏季降水存在反相變化。REOF結(jié)果進(jìn)一步給出了新疆夏季降水異常的敏感區(qū)域,可將新疆地區(qū)細(xì)分為五個(gè)區(qū)域。五個(gè)區(qū)內(nèi)站點(diǎn)的平均年降水量均呈增長(zhǎng)趨勢(shì),夏季增長(zhǎng)趨勢(shì)最大,2區(qū)的平均年降水量最大,3、5區(qū)次之,且5區(qū)增長(zhǎng)趨勢(shì)最快。應(yīng)用SOM神經(jīng)網(wǎng)絡(luò)算法將包含新疆在內(nèi)的研究區(qū)域1961-2013年5-9月逐日的海平面氣壓場(chǎng)進(jìn)行天氣分型,得到35類天氣型。結(jié)合降水資料確定出影響新疆地區(qū),尤其是北疆夏季降水的主要天氣系統(tǒng)是發(fā)生在5月、7月和9月地面氣旋和地面高壓前的鋒面系統(tǒng)。每個(gè)天氣型對(duì)年降水量的貢獻(xiàn)表明,新疆近50%的平均年降水量期望值集中在對(duì)新疆降水貢獻(xiàn)較大的13個(gè)結(jié)點(diǎn),體現(xiàn)了 SOM天氣分型對(duì)研究新疆降水的重要性。NAO是新疆降水年際變化的重要因子之一,NAO指數(shù)與新疆年降水量呈負(fù)相關(guān),與年降水增量呈顯著負(fù)相關(guān)。在NAO異常年份,冰島低壓和北大西洋高壓強(qiáng)度異常,通過配合高空以及地面天氣系統(tǒng)的發(fā)展移動(dòng)進(jìn)而影響了新疆地區(qū)的降水活動(dòng)。因而掌握好NAO指數(shù)的異常變化規(guī)律及預(yù)測(cè),對(duì)于新疆地區(qū)的降水預(yù)報(bào)具有重要意義。
[Abstract]:Under the background of global climate change, it is of great scientific and social significance to study the regional characteristics of precipitation changes and the weather situation affecting precipitation in Xinjiang. In this paper, the daily precipitation data of 47 meteorological stations in Xinjiang from 1961 to 2013 are selected to analyze the temporal and spatial distribution of precipitation in Xinjiang, and the climatic zoning of summer precipitation in Xinjiang is carried out by using EOF,REOF method. The results show that the precipitation in Xinjiang region shows a continuous increasing trend from 1961 to 2013. After 1987, the precipitation is on the high side. Summer is the season that contributes most to the annual precipitation in Xinjiang in one year, which dominates the spatial distribution of annual precipitation and the changing trend of annual precipitation. The annual precipitation in Xinjiang is more and less in the north and south, and the precipitation in the whole of Xinjiang is rising. The four modes of EOF reflect the consistency of the summer precipitation changes in Xinjiang, and the blocking of the Tianshan Mountains causes the difference between the changes in the south and the north of Xinjiang, and the four modes of EOF reflect the consistency of the summer precipitation in Xinjiang. There are inverse variations of summer precipitation in eastern and western Xinjiang, central Tianshan mountain area and other areas. The REOF results further show the sensitive areas of summer precipitation anomaly in Xinjiang, which can be divided into five regions. The average annual precipitation of the five regions all showed an increasing trend, with the largest increasing trend in summer, the largest average annual precipitation in the two regions, the third in the fifth region and the fastest in the fifth region. The SOM neural network algorithm is used to classify the daily sea level pressure field from May to September from 1961 to 2013 in the study area including Xinjiang, and 35 types of weather patterns are obtained. Combined with precipitation data, the main weather systems affecting summer precipitation in Xinjiang, especially in northern Xinjiang, are the frontal systems which occur before the surface cyclones and surface high in May, July and September. The contribution of each climate type to the annual precipitation indicates that nearly 50% of the expected annual precipitation in Xinjiang is concentrated in the 13 nodes which contribute more to the precipitation in Xinjiang. NAO is one of the important factors in the inter-annual variation of precipitation in Xinjiang. The NAO index is negatively correlated with the annual precipitation in Xinjiang and negatively correlated with the annual precipitation increment. The SOM weather classification is of great importance to the study of precipitation in Xinjiang. In the year of NAO anomaly, the intensity anomaly of Icelandic low and North Atlantic high influenced the precipitation activity in Xinjiang by cooperating with the development and movement of high altitude and surface weather system. Therefore, it is of great significance to master the abnormal variation law and forecast of NAO index for precipitation forecast in Xinjiang.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P426.6

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