發(fā)布時(shí)間：2017-12-31 13:19

  本文關(guān)鍵詞：東亞高空急流協(xié)同變化特征及其機(jī)理研究　出處：《南京大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 東亞高空急流 協(xié)同變化 極地增暖 局地波活動(dòng) 極端事件

【摘要】：東亞高空急流是北半球重要大氣環(huán)流系統(tǒng)之一。東亞副熱帶急流和極鋒急流的協(xié)同變化既可以反映中高緯度環(huán)流系統(tǒng)的作用,又可以反映低緯度環(huán)流信號(hào)的異常,還能夠與大氣低頻遙相關(guān)緊密聯(lián)系在一起,對(duì)東亞天氣氣候系統(tǒng)的影響起到橋梁或者紐帶的作用。本文利用NCEP/NCAR再分析資料,得到冬季東亞陸地上空高空急流的主要模態(tài),揭示出副熱帶急流和極鋒急流位置和強(qiáng)度的協(xié)同變化關(guān)系,進(jìn)而研究高空急流協(xié)同變化的氣候效應(yīng)。從熱力學(xué)和動(dòng)力學(xué)兩個(gè)方面分別討論急流協(xié)同變化的機(jī)理。評(píng)估AMIP模式對(duì)東亞高空急流協(xié)同變化的模擬能力,并分析極地增暖對(duì)東亞地區(qū)急流協(xié)同變化的影響。利用局地有限振幅波活動(dòng)及其能量平衡方程診斷出海冰融化對(duì)局地反氣旋波活動(dòng)以及對(duì)中緯度地區(qū)極端事件的影響機(jī)制。全文主要結(jié)論如下:一、東亞高空急流位置和強(qiáng)度的協(xié)同變化特征東亞地區(qū)高空急流包括副熱帶急流和極鋒急流。通過(guò)東亞地區(qū)急流核的分布確定了陸地上空這兩支急流的關(guān)鍵區(qū)域。對(duì)陸地上空緯向風(fēng)進(jìn)行EOF分析發(fā)現(xiàn),東亞陸地上空兩支急流變化的主要模態(tài)分別對(duì)應(yīng)副熱帶急流和極鋒急流位置和強(qiáng)度的反位相變化特征。當(dāng)兩支急流距離較近,即極鋒急流偏南、副熱帶急流偏北時(shí),兩支急流的強(qiáng)度均增強(qiáng);當(dāng)兩支急流互相遠(yuǎn)離,即極鋒急流偏北、副熱帶急流偏南時(shí),兩支急流的強(qiáng)度均減弱。從對(duì)應(yīng)的大氣環(huán)流異常來(lái)看,當(dāng)兩支急流靠近時(shí),東亞大槽減弱,東亞中緯度地區(qū)位勢(shì)高度增加,太平洋北部西風(fēng)減弱;而當(dāng)兩支急流遠(yuǎn)離時(shí),中緯度位勢(shì)高度減弱,東亞大槽增強(qiáng)。急流位置變化模態(tài)對(duì)應(yīng)的500hPa位勢(shì)高度異常分布在歐亞-太平洋地區(qū)呈現(xiàn)出正負(fù)正(或負(fù)正負(fù))的特征,與中緯度歐亞遙相關(guān)型相似;對(duì)應(yīng)的海平面氣壓場(chǎng)異常分布表現(xiàn)為極地區(qū)域與中緯度洋面的反位相變化,與北極濤動(dòng)相似。二、東亞高空急流協(xié)同變化的機(jī)制影響急流位置和強(qiáng)度變化的原因除了非絕熱加熱異常、海溫異常等外強(qiáng)迫因子外,大氣內(nèi)部動(dòng)力學(xué)過(guò)程也會(huì)通過(guò)波流相互作用對(duì)其產(chǎn)生一定的影響。因此,從熱力學(xué)和動(dòng)力學(xué)兩個(gè)方面分析影響急流位置和強(qiáng)度協(xié)同變化的可能機(jī)制。從熱力學(xué)方面看,當(dāng)兩支急流距離較近時(shí),從溫度平流方程得到非絕熱加熱以及水平熱量輸送的作用增加了南北溫度梯度,根據(jù)熱成風(fēng)原理,增大的經(jīng)向溫度梯度能夠增強(qiáng)副熱帶急流與極鋒急流的強(qiáng)度,從而使兩支急流的強(qiáng)度增加。當(dāng)兩支急流相距較遠(yuǎn)時(shí),非絕熱加熱以及水平熱量輸送的作用減弱,導(dǎo)致南北溫度梯度減小,從而減弱了兩支急流的強(qiáng)度。從動(dòng)力學(xué)方面來(lái)看,低層斜壓性與中緯度天氣尺度瞬變活動(dòng)聯(lián)系緊密而對(duì)副熱帶地區(qū)無(wú)顯著影響。當(dāng)兩支急流相距較近時(shí),天氣尺度瞬變波E矢量在極鋒急流區(qū)存在輻散中心,加強(qiáng)了該區(qū)域緯向風(fēng)速,從而使極鋒急流增強(qiáng)。當(dāng)兩支急流相距較遠(yuǎn)時(shí),輻散中心減弱甚至轉(zhuǎn)為輻合,從而使極鋒急流減弱。除此之外,定常波E-P通量通過(guò)增強(qiáng)或減弱緯向風(fēng)速來(lái)改變兩支急流的強(qiáng)度。兩支急流靠近時(shí),急流區(qū)均出現(xiàn)E-P通量輻散中心,增強(qiáng)了兩支急流的強(qiáng)度;兩支急流遠(yuǎn)離時(shí),輻散中心的減弱與輻合中心的出現(xiàn)使兩支急流強(qiáng)度均減弱。三、極地增暖對(duì)高空急流協(xié)同變化的影響通過(guò)AMIP試驗(yàn)將海冰融化的外源強(qiáng)迫單獨(dú)分離開(kāi)來(lái)分析海冰融化對(duì)東亞地區(qū)高空急流的位置和強(qiáng)度協(xié)同變化的影響,從AMIP海冰控制試驗(yàn)的模式數(shù)據(jù)分析海冰融化產(chǎn)生的風(fēng)場(chǎng)異�？梢缘玫�,該模式既能模擬出兩支急流強(qiáng)度協(xié)同變化,也能模擬出兩支急流位置協(xié)同變化。海冰融化導(dǎo)致兩支急流的強(qiáng)度都存在年際變化,但是整體趨勢(shì)不顯著;極鋒急流的位置不僅存在年際變化,還存在明顯的年代際變化,整體趨勢(shì)偏南2.5°左右,而副熱帶急流位置變化不明顯。進(jìn)一步利用EOF時(shí)間序列對(duì)緯向風(fēng)和經(jīng)向風(fēng)距平場(chǎng)進(jìn)行回歸可以看出,自20世紀(jì)90年代中后期,尤其是21世紀(jì)以來(lái),極地增暖致使極鋒急流強(qiáng)度減弱,主要表現(xiàn)為緯向風(fēng)異常減弱,經(jīng)向風(fēng)異常增加。四、極地增暖對(duì)北半球中緯度極端事件的影響及機(jī)制利用有限振幅波活動(dòng)方法分析500hPa位勢(shì)高度場(chǎng)得到局地波活動(dòng)特征,并通過(guò)量綱分析將局地波活動(dòng)分解成平均梯度和渦動(dòng)擾動(dòng)尺度兩項(xiàng),分別對(duì)應(yīng)著波活動(dòng)的熱力學(xué)變化和動(dòng)力學(xué)變化特征。對(duì)再分析資料和AMIP數(shù)據(jù)中計(jì)算出的有限振幅波活動(dòng)、擾動(dòng)尺度的趨勢(shì)分析得出,觀測(cè)數(shù)據(jù)中中緯度緯向平均波活動(dòng)的增加以及波動(dòng)經(jīng)向擾動(dòng)增加的趨勢(shì)無(wú)法在歷史模式尤其是海冰控制模式中模擬出來(lái),這說(shuō)明波活動(dòng)異常與北極地區(qū)的海冰融化無(wú)顯著的聯(lián)系,很有可能是由于大氣內(nèi)部變率的作用。但是從局地的波活動(dòng)變化特征中發(fā)現(xiàn)無(wú)論是再分析資料還是模式數(shù)據(jù),北半球中緯度尤其是歐亞中北部地區(qū)局地反氣旋波活動(dòng)均存在顯著的增加趨勢(shì)。而500hPa反氣旋波活動(dòng)往往與阻塞高壓等天氣系統(tǒng)聯(lián)系在一起,對(duì)局地天氣氣候的異常產(chǎn)生影響。反氣旋活動(dòng)大值中心南北兩側(cè)極端暖事件和極端冷事件概率均有所增加也證實(shí)了這個(gè)觀點(diǎn)。通過(guò)能量方程診斷分析發(fā)現(xiàn)極地海冰融化較快的巴倫支海-喀拉海地區(qū)的反氣旋波活動(dòng)水平輸送是歐亞地區(qū)反氣旋波活動(dòng)增加的源,與此同時(shí)水平輸送將極地地區(qū)冷空氣向南輸送造成極端冷事件的發(fā)生。
[Abstract]:The Asian jet is one of the important atmospheric circulation systems in the northern hemisphere. Coordinated variation of the East Asian subtropical westerly jet and polar front jet can reflect in the high latitude circulation system, but also can reflect the abnormal signal of the low latitude circulation, but also with the Atmospheric Low-Frequency teleconnection closely linked to the bridge, or the link to the influence of East Asian climate system. The weather by using NCEP/NCAR reanalysis data, the main modes of the winter East Asian jet stream over the land, to reveal the relationship between collaborative subtropical jet and polar front jet location and intensity, and climate effect of high-altitude jet changes. Discuss the mechanism of collaborative jet coordinated changes from two aspects of thermodynamics and dynamics respectively. Simulation capability of collaborative AMIP model to assess changes in the Asian jet, and the analysis of polar warming on the East Asian Jet collaborative change The influence of local. By using the finite amplitude wave activity and energy balance equation on the diagnosis of ice anticyclonic wave activity and on the mid latitude regions of extreme events influence mechanism. The main conclusions are as follows: first, concurrent changes in East Asia westerly jet location and intensity characteristics of East Asia westerly jet including subtropical jet and polar front the key area of land over the rapids. This two jets is determined by the distribution of East Asia. The jet core EOF analysis of zonal wind over the land, anti phase change characteristics of main modes of East Asian over land two jet changes respectively corresponding to the subtropical jet and polar front jet location and strength. When the two jets the short distance, namely the polar front southerly jet, north subtropical jet, strength of two jets increased; when the two jets away from each other, namely the polar front jet north subtropical acute Flow south, strength of two jets were decreased. The atmospheric circulation anomalies corresponding to the view, when close to two jets, the East Asian Trough weakened in mid latitude East Asia geopotential height increase, the North Pacific westerly weakened; and when away from the two jets, mid latitude potential high degree of weakening of East Asia trough enhancement. Jet position change mode corresponding to the 500hPa geopotential height anomaly distribution in Eurasia Pacific region showing a positive negative positive (or negative negative) characteristics, and mid latitude Eurasian teleconnection pattern is similar; the sea level pressure corresponding to the abnormal distribution for the polar regions and in the latitudes of phase, and the Arctic oscillation is similar. Two, the mechanism of the Asian Jet coordinated changes influence the position and intensity of the jet in addition to diabatic heating anomalies, SST anomalies of external forcing factors, internal atmospheric dynamic process will flow through the waves The interaction have a certain impact on it. Therefore, analysis of the impact of the possible mechanism of change of the position and intensity of collaborative jet from two aspects of thermodynamics and kinetics. From the thermodynamic aspect, when the two jet distance, from the temperature advection equation of non adiabatic heating and heat transfer level to increase the role of the north-south temperature gradient and according to the principle of thermal wind, increasing the meridional temperature gradient can enhance the subtropical westerly jet and polar front jet intensity, so that the intensity of two jets increases. When the distance of two jets is far away, the weakening effect of non adiabatic heating and heat transfer level, leading to the north-south temperature gradient decreases, thereby weakening the strength of two a. From the dynamic perspective, low-level baroclinicity and mid latitude synoptic scale transient activity is closely linked to the subtropical regions had no significant effect. When the distance of two a short day, Gas scale transient wave E vector divergence center in the polar front jet region, strengthens the regional zonal wind velocity, so that the polar front jet is enhanced. When the distance of two jets is far away, the divergence center weakened and even to convergence, so that the polar front jet weakened. In addition, Chang Bo E-P the amount of pass through increased or decreased zonal wind velocity to change the intensity of two jets. Near two jets, the jet appeared E-P flux divergence center, enhance the strength of two jets; from two jets, there is weakening and convergence center divergence center of the two jets are strong weakened. Three effects of warming on the polar jet coordinated changes through the AMIP test will be forced to separate exogenous ice separating effect analysis of coordinated changes in East Asia melting sea ice jet location and intensity, from the number of AMIP control test points according to the sea ice The wind of melting sea ice anomalies generated by the model can be obtained, which can simulate the change of collaborative two jet strength, can also simulate two jet location collaborative change. Sea ice melting leads to the strength of two jets have interannual variation, but the overall trend is not significant; the position of the polar front jet not only exist interannual variation there are obvious interdecadal changes, the overall trend of the south of about 2.5 degrees, and the change of position of the subtropical jet is not obvious. The further use of EOF time series of zonal wind and meridional wind anomaly field regression can be seen, since late 1990s, especially since twenty-first Century, the polar warming in polar front jet intensity mainly for the zonal wind anomaly weakened by an abnormal increase in wind. Four, the polar warming effect on the mid latitudes of the northern hemisphere and the mechanism of extreme events using finite amplitude wave activity analysis method 500hPa Potential height field characteristics of bureau ground wave activity, and by dimensional analysis bureau ground wave activities into average gradient and eddy scale two, which corresponds to the thermodynamic changes and dynamic change characteristics of wave activity. The analysis of calculation data and AMIP data in finite amplitude wave activity analysis of disturbance scale trend the increase in the observed data in the mid latitude zonal mean meridional wave activity and fluctuation disturbance increasing trend in history cannot mode especially simulated sea ice control mode, which shows that the wave activity had no significant relationship with the Arctic sea ice melts, it is probably due to the atmospheric internal variability effect. But from the variation of local wave activity found in both reanalysis data and model data, latitudes in the northern hemisphere especially the north central region of the Eurasian anticyclone wave activities are local A significant increasing trend. The 500hPa activity is often associated with anticyclonic wave blocking high weather system together, abnormal weather and climate impact on the anti cyclone activity value centre. The north and south sides of extreme warm events and extreme cold event probability increased also confirmed this point. Through the diagnosis analysis found that the polar energy equation sea ice melts faster the Barents Kara Sea region of the anticyclonic wave activity transportation is anticyclonic wave activity in Eurasia increased, at the same time the level of transmission will polar region cold air southward transport caused by extreme cold events.

【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：P442

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本文編號(hào)：1359945