本文關(guān)鍵詞：昆明準靜止鋒的生成機制研究　出處：《云南大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 昆明準靜止鋒 資料序列 生成機制 鋒生函數(shù)

【摘要】：本文利用2010年1月1日-2014年12月31日逐日ERA-Interim再分析資料、常規(guī)觀測資料,用昆明與貴陽溫度差異為參數(shù)對逐日資料進行普查,然后利用合成分析,相關(guān)分析等方法對所得昆明準靜止鋒過程序列進行了檢驗,最終建立了一個連續(xù)的昆明準靜止鋒時間序列。在確認所得昆明準靜止鋒過程序列的可靠性后,對2010-2014年間昆明準靜止鋒過程的氣候?qū)W特征進行了分析,并由此得到了昆明準靜止鋒的平均鋒線位置。隨后使用鋒生公式對昆明準靜止鋒過程逐一進行診斷分析,比較鋒生函數(shù)的各分項對昆明準靜止鋒生成的貢獻,以獲得昆明準靜止鋒的生成機制。研究結(jié)果表明：(1)用昆明與貴陽之間的溫度差值作為參數(shù),以標準化差值大于0.8倍標準差且持續(xù)兩天及以上為標準,可獲得一個連續(xù)的昆明準靜止鋒時間序列。通過與2004-2005冬春季和2010年兩個時段站點觀測資料的對比,發(fā)現(xiàn)上述準靜止鋒過程挑選方法簡單可行,所得昆明準靜止鋒過程序列具有較高的可靠性。(2)在2010-2014年的研究時段內(nèi),共挑出昆明準靜止鋒過程日343日,分為67次過程；平均每年68.6天,平均過程數(shù)13.4次,每次過程平均持續(xù)5天；從鋒面過程次數(shù)的年際變化來看,2010-2014年間鋒面過程數(shù)最多的是2010年,統(tǒng)計得到17次；過程數(shù)最少的是2013年,為11次。(3)通過Hewson提出的客觀定鋒方法對2008年1月-2月間的昆明準靜止鋒進行了客觀定鋒試驗,發(fā)現(xiàn)使用合適的鋒面定位函數(shù)和掩膜變量閾值可以由格點資料客觀確定出昆明準靜止鋒的鋒線位置。通過對不同高度、不同鋒面定位函數(shù)和不同掩膜變量閾值情況下的大量試驗,確定出了適合冬季昆明準靜止鋒客觀定鋒的定位函數(shù)和掩膜變量閾值。(4)對挑選出的準靜止鋒過程進行合成分析發(fā)現(xiàn),在800hPa以下,鋒面兩側(cè)存在明顯的溫度梯度,風場上也表現(xiàn)出明顯的風速或風向的輻合。而在700hPa以上溫度梯度和風場的輻合都減弱消失。但在不同層次上,鋒前鋒后的濕度場都沒有明顯的干濕對比。由溫度場和風場的合成結(jié)果發(fā)現(xiàn),平均來說,850hPa上昆明準靜止鋒鋒線的走向在27°N附近有一次轉(zhuǎn)折,在27°N-29°N之間,從105°E附近向西北延伸至102.5°E附近,鋒線呈西北-東南向；而在23°N-27°N之間,鋒線在104°E-105°E間呈準南北向分布。(5)利用運動學(xué)鋒生公式計算昆明準靜止鋒過程序列中逐日的鋒生函數(shù),發(fā)現(xiàn)在昆明準靜止鋒的平均位置附近,的確有鋒生函數(shù)的大值區(qū)出現(xiàn)；鋒生函數(shù)大值中心的位置和走向與平均鋒線的位置和走向基本一致。這一方面說明鋒生公式可以很好地描述昆明準靜止的的生成、維持,另一方面也反證了本文第二章中昆明準靜止鋒過程挑選的方法是可行的。通過對比鋒生函數(shù)四個分項平均值與各分項的格點平均鋒生強度發(fā)現(xiàn),對昆明準靜止鋒鋒生起直接作用的是水平輻散項和水平切變項,與垂直運動相關(guān)的傾斜項的作用則可以忽略。進一步分析鋒生函數(shù)在鋒生過程中的時間演變,發(fā)現(xiàn)非絕熱加熱項的作用對鋒面生成有觸發(fā)作用。(6)昆明準靜止鋒生成機制為：低層冷空氣西進遇到地形抬升,凝結(jié)潛熱釋放加熱氣柱；在此非絕熱加熱的強迫下,鋒面附近出現(xiàn)熱力間接環(huán)流,加劇鋒面前后的溫度梯度,觸發(fā)了昆明準靜止鋒的生成：此后水平運動的鋒生作用使昆明準靜止鋒進一步發(fā)展。
[Abstract]:The January 1, 2010 -2014 year in December 31st the daily ERA-Interim reanalysis data, conventional observation data, with Kunming and Guiyang as the temperature difference between the parameters of the census and use daily data, synthetic analysis, correlation analysis and other methods for the program listed Kunming quasi tested, finally established a Kunming quasi continuous time series. In the confirmation of the reliability the Kunming quasi process sequence, on the climatic characteristics of Kunming during the period of 2010-2014 quasi stationary process is analyzed, and the resultant average forward positions of the quasi stationary front in Kunming. Then use the formula of Kunming quasi stationary front frontogenesis process by diagnostic analysis, comparison of the sub frontogenesis function generated by the quasi stationary front in Kunming. The contribution to obtain the formation mechanism of the quasi stationary front in Kunming. The results show that: (1) in Kunming and Guiyang The temperature difference between as parameters, greater than 0.8 times the standard deviation and lasts for two days with the standardized difference and above the standard, can obtain a Kunming quasi continuous time series. By comparison with 2004-2005 in winter and spring and 2010 two period site observation, found on the quasi stationary process of selecting method is simple and feasible. The Kunming quasi sequence has high reliability. (2) in the study period of 2010-2014 years, were singled out Kunming quasi 343 days process, divided into 67 process; an average of 68.6 days per year, the average number of 13.4 times, each time the process lasted an average of 5 days; the number of the process from the inter annual change of front view during 2010-2014 process, the front is the largest number of statistics in 2010, 17; the number of process at least in 2013, 11. (3) objective method proposed by Hewson in front of the month of January 2008 -2 Kunming quasi objective of front test, found that the use of appropriate function and positioning the front mask by the grid data of variable threshold can objectively determine the Kunming quasi strike position. According to the different height, a large number of experiments with different functions and different positioning front mask variable threshold conditions, determine a suitable positioning function winter Kunming quasi objective front and mask variable threshold. (4) the synthesis analysis of quasi selected process found below 800hPa, both sides of the front has obvious temperature gradient, wind field also showed obvious convergence of wind speed and wind direction. At 700hPa above the temperature gradient and wind field the convergence of all go away. But at different levels, the humidity field front striker after all wet and dry contrasting. The results show that the synthetic results of wind and temperature field on average, 850hPa Kunming To the front of the quasi stationary front there is a turning point in the vicinity of 27 DEG N between 27 DEG N-29 DEG N, extending from near 105 DEG E to 102.5 DEG E to the northwest near the front, a northwest southeast direction; between 23 DEG N-27 DEG N, in front of 104 ~ E-105 ~ E between North and south is quasi to distribution. (5) the frontogenesis function to calculate the daily Kunming quasi process sequence using kinematic frontogenesis formula, found in the vicinity of the average position of the quasi stationary front in Kunming, there are large values of the frontogenesis function area; frontogenesis function position and value to the center and the average attack position and direction are consistent. On the one hand that formula can well describe frontogenesis generation, Kunming quasi stationary maintenance, on the other hand also reflects the method in the second chapter, Kunming quasi selection process is feasible. By contrast the four sub lattice frontogenesis function average value of each item are flat and The frontogenesis found Kunming quasi stationary front frontogenesis play a direct role is the horizontal divergence and horizontal shear, and the vertical movement of the tilting effect can be ignored. Further analysis of the frontogenesis function in time evolution in the frontogenesis process, found that the non adiabatic heating effect has the effect on triggering (frontogenesis. 6) Kunming quasi generation mechanism: low level cold air westward encountering terrain uplift, release of the latent heat of condensation heating gas column; this diabatic heating forced heat, indirect circulation near the front, increasing the temperature gradient and the front trigger generation, Kunming quasi stationary front frontogenesis: horizontal movement to Kunming since then the further development of the quasi stationary front.

【學(xué)位授予單位】：云南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：P441

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