昆明准静止锋的生成机制研究

发布时间：2017-12-31 18:30

本文关键词：昆明准静止锋的生成机制研究　出处：《云南大学》2016年博士论文　论文类型：学位论文

【摘要】：本文利用2010年1月1日-2014年12月31日逐日ERA-Interim再分析资料、常规观测资料,用昆明与贵阳温度差异为参数对逐日资料进行普查,然后利用合成分析,相关分析等方法对所得昆明准静止锋过程序列进行了检验,最终建立了一个连续的昆明准静止锋时间序列。在确认所得昆明准静止锋过程序列的可靠性后,对2010-2014年间昆明准静止锋过程的气候学特征进行了分析,并由此得到了昆明准静止锋的平均锋线位置。随后使用锋生公式对昆明准静止锋过程逐一进行诊断分析,比较锋生函数的各分项对昆明准静止锋生成的贡献,以获得昆明准静止锋的生成机制。研究结果表明：(1)用昆明与贵阳之间的温度差值作为参数,以标准化差值大于0.8倍标准差且持续两天及以上为标准,可获得一个连续的昆明准静止锋时间序列。通过与2004-2005冬春季和2010年两个时段站点观测资料的对比,发现上述准静止锋过程挑选方法简单可行,所得昆明准静止锋过程序列具有较高的可靠性。(2)在2010-2014年的研究时段内,共挑出昆明准静止锋过程日343日,分为67次过程；平均每年68.6天,平均过程数13.4次,每次过程平均持续5天；从锋面过程次数的年际变化来看,2010-2014年间锋面过程数最多的是2010年,统计得到17次；过程数最少的是2013年,为11次。(3)通过Hewson提出的客观定锋方法对2008年1月-2月间的昆明准静止锋进行了客观定锋试验,发现使用合适的锋面定位函数和掩膜变量阈值可以由格点资料客观确定出昆明准静止锋的锋线位置。通过对不同高度、不同锋面定位函数和不同掩膜变量阈值情况下的大量试验,确定出了适合冬季昆明准静止锋客观定锋的定位函数和掩膜变量阈值。(4)对挑选出的准静止锋过程进行合成分析发现,在800hPa以下,锋面两侧存在明显的温度梯度,风场上也表现出明显的风速或风向的辐合。而在700hPa以上温度梯度和风场的辐合都减弱消失。但在不同层次上,锋前锋后的湿度场都没有明显的干湿对比。由温度场和风场的合成结果发现,平均来说,850hPa上昆明准静止锋锋线的走向在27°N附近有一次转折,在27°N-29°N之间,从105°E附近向西北延伸至102.5°E附近,锋线呈西北-东南向；而在23°N-27°N之间,锋线在104°E-105°E间呈准南北向分布。(5)利用运动学锋生公式计算昆明准静止锋过程序列中逐日的锋生函数,发现在昆明准静止锋的平均位置附近,的确有锋生函数的大值区出现；锋生函数大值中心的位置和走向与平均锋线的位置和走向基本一致。这一方面说明锋生公式可以很好地描述昆明准静止的的生成、维持,另一方面也反证了本文第二章中昆明准静止锋过程挑选的方法是可行的。通过对比锋生函数四个分项平均值与各分项的格点平均锋生强度发现,对昆明准静止锋锋生起直接作用的是水平辐散项和水平切变项,与垂直运动相关的倾斜项的作用则可以忽略。进一步分析锋生函数在锋生过程中的时间演变,发现非绝热加热项的作用对锋面生成有触发作用。(6)昆明准静止锋生成机制为：低层冷空气西进遇到地形抬升,凝结潜热释放加热气柱；在此非绝热加热的强迫下,锋面附近出现热力间接环流,加剧锋面前后的温度梯度,触发了昆明准静止锋的生成：此后水平运动的锋生作用使昆明准静止锋进一步发展。
[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.

【学位授予单位】：云南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P441

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