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廣州地區(qū)天氣分型和降水預(yù)估

發(fā)布時間:2018-07-23 09:41
【摘要】:廣州位于我國沿海珠江三角洲城市群區(qū),常年受季風(fēng)影響,是強降水和城市內(nèi)澇的災(zāi)害高頻區(qū)。本文采用廣州增城站1990年1月至2013年9月的小時觀測資料、地面和高空 925hPa、850hPa、700hPa、600hPa、500hPa 的 JRA55 再分析資料、CMA熱帶氣旋最佳路徑、日本氣象廳地面天氣圖、歷史模擬和RCP2.6、RCP4.5、RCP8.5三種典型路徑下的IPSL-CM5A模式資料,通過天氣分型和降水量預(yù)估的方法分析了降水天氣特征和局地氣候變化。首先,通過主成分分析、聚類分析和判別分析建立CA(Cluster Analysis)天氣分型并通過逐步logistic回歸和非線性回歸建立日降水量模擬。CA天氣分型共包括38種天氣型,其中包括6種臺風(fēng)天氣型,分別對應(yīng)著臺風(fēng)位于增城以西、附近、以南、以北、附近(多發(fā)于春秋)和多天氣系統(tǒng)聯(lián)合影響這六種情況。降水模擬中,對于總降水事件和臺風(fēng)降水事件,小雨和中雨的模擬效果較好,大雨的模擬效果有待于提高。其次,通過SOM神經(jīng)網(wǎng)絡(luò)法建立SOM(Self-Organizing Map)天氣分型并分析各型的氣候意義及主要降水類。SOM天氣分型共包括20種天氣型,分布于4X5 SOM神經(jīng)網(wǎng)絡(luò)中,可識別出冬季風(fēng)和夏季風(fēng)的典型天氣形態(tài),沿神經(jīng)網(wǎng)絡(luò)邊界逆時針旋轉(zhuǎn)的高頻天氣型年循環(huán),和三種降水天氣類,分別為:前汛期鋒面類、后汛期臺風(fēng)類和非汛期冷高壓類。然后,通過統(tǒng)計降尺度,將歷史模擬和RCP2.6、RCP4.5、RCP8.5三種典型路徑下的IPSL-CM5A模式逐日區(qū)域格點資料降尺度成逐時站點資料。此統(tǒng)計降尺度方法的降尺度數(shù)據(jù)在增城有較好的模擬效果,可準確反應(yīng)出各氣象要素的日循環(huán)和年循環(huán)等特征,并表現(xiàn)出各氣象要素在不同情景下21世紀內(nèi)的時間變化。RCP2.6情景下,在21世紀初期至中期,增城區(qū)域溫度約升幅2℃,高溫日年頻率升至約60天,21世紀中期至末期,溫度變化不大;在21世紀內(nèi),濕度條件近乎不變。RCP4.5情景下,增城區(qū)域溫度升高、濕度減小,變化強度介于RCP2.6和RCP8.5之間。RCP8.5情景下,升溫幅度最大,在21世紀末會有更多的高溫日,濕度減弱,10m風(fēng)速中北風(fēng)分量減弱,高空西風(fēng)帶減弱。最后,依據(jù)統(tǒng)計降尺度后的模式數(shù)據(jù),基于CA天氣分型降水量模擬和SOM天氣分型分析,預(yù)估未來降水形勢。兩種天氣分型的預(yù)估結(jié)果相似:(1)三種典型情景下,21世紀均會有更熱更旱的趨勢;降水日數(shù)減少但平均日降水量變化較小,受臺風(fēng)影響的頻數(shù)和總降水量減少,極端降水事件可能增加,極端降水事件和臺風(fēng)帶來的災(zāi)害可能增加。(2)三種典型情景之間,RCP8.5的降水發(fā)生于更熱更旱的天氣型中的可能性最大,其次為RCP4.5,RCP2.6的可能性最小。SOM天氣分型未來降水預(yù)估中,在21世紀末期,RCP8.5的主要降水事件性質(zhì)發(fā)生變化,由暖濕的天氣型(4,1)轉(zhuǎn)而集中于熱干的天氣型(1,1)中;RCP4.5情景下也有此變化趨勢,但變化程度偏小;RCP2.6中主要降水事件依舊集中于天氣型(4,1)中。
[Abstract]:Guangzhou is located in the urban agglomeration of the Pearl River Delta along the coast of China. It is affected by monsoon and is the high frequency area of heavy rainfall and urban waterlogging. This paper uses the observation data of Guangzhou Zengcheng station from January 1990 to September 2013, the JRA55 reanalysis data of the ground and high altitude 925hPa, 850hPa, 700hPa, 600hPa, 500hPa, and the best path of the CMA tropical cyclone. The ground weather map of the Japan Meteorological Office, the historical simulation and the IPSL-CM5A model data under three typical paths of RCP2.6, RCP4.5 and RCP8.5 are used to analyze the precipitation weather characteristics and local climate change through the weather classification and the precipitation prediction method. First, the CA (Cluster Analysis) weather points are established by the principal component analysis, the cluster analysis and the discriminant analysis. 38 types of weather patterns, including 6 types of typhoon weather patterns, are composed of 6 types of weather patterns, which correspond to the six types of combined effects of typhoon located in the west of Zengcheng, South, north, near (mostly in spring and Autumn) and multi day gas system, respectively, in precipitation simulation. The total precipitation events and typhoon precipitation events, the simulation effect of the rain and the rain are better, the simulation effect of the heavy rain needs to be improved. Secondly, the SOM neural network method is used to establish the SOM (Self-Organizing Map) weather classification and to analyze the climatic significance of each type and the main precipitation type.SOM weather types, including 20 types of weather patterns, distributed in the 4X5 SOM neural network. In the collaterals, the typical weather patterns of the winter monsoon and the summer monsoon are identified, the high frequency synoptic cycle that rotates clockwise along the neural network boundary, and three kinds of precipitation weather types, respectively, the front season front, the late flood season typhoon and the cold and high pressure in the non flood season. Then, the historical simulation and the RCP2.6, RCP4.5, and RCP8.5 codes are made through the descending scale. The IPSL-CM5A model has a good simulation effect in Zengcheng, which can accurately reflect the characteristics of the daily cycle and the annual cycle of the meteorological elements, and show the time changes of the meteorological elements in the different scenarios in twenty-first Century. In the period of.RCP2.6, in the early and middle period of twenty-first Century, the temperature of Zengcheng region rose about 2 degrees C, the frequency of high temperature rose to about 60 days, and the temperature changed little in the middle to the end of twenty-first Century. In twenty-first Century, the humidity condition was almost unchanged in the.RCP4.5 situation, the temperature of Zengcheng region increased, the humidity decreased, and the change intensity was in the.RCP8.5 scenario between RCP2.6 and RCP8.5. In the end of twenty-first Century, there will be more hot days and more high temperature days in the end of twenty-first Century, the humidity is weakened, the north wind component in the 10m wind speed is weakened, and the high altitude westerly belt is weakened. Finally, based on the model data of the descending scale, based on the CA weather precipitation simulation and the SOM weather classification analysis, the future precipitation situation is estimated. The prediction results of the two types of weather classification are similar. (1) under the three typical scenarios, there will be a hotter and more drought trend in twenty-first Century; the number of precipitation days decreases but the average daily precipitation changes smaller, the frequency and total precipitation affected by the typhoon are reduced, the extreme precipitation events may increase, the extreme precipitation events and typhoons can increase. (2) three typical scenarios, the precipitation of RCP8.5 The most hot and dry weather pattern is most likely, followed by RCP4.5, RCP2.6, the minimum possibility of.SOM weather classification in the future precipitation prediction, in the late twenty-first Century, the main precipitation events of the RCP8.5 changed from the warm wet weather type (4,1) to the hot dry weather type (1,1); but the RCP4.5 scenario also has this trend, but there is this change trend, but the RCP4.5 situation also has this trend. The main precipitation events in RCP2.6 are still concentrated in the weather pattern (4,1).
【學(xué)位授予單位】:南京大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2017
【分類號】:P426.6;P44

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