Statistical Characteristics of Short-time Heavy Precipitation in Shan-Gan-Ning Region from May to September in Recent 6 Years
-
摘要: 利用2005—2010年5—9月加密自动气象站1 h降水资料对陕甘宁三省不同强度短时强降水时空分布特征、天气学概念模型以及物理量特征进行研究,结果表明:短时强降水在陕甘宁三省存在4个活跃区和3个不活跃区;7—8月是短时强降水的多发期,两大峰值出现在7月下旬和8月中旬,日变化呈双峰分布,1 h降水量≥30 mm的短时强降水具有夜间多发性;通过典型个例的综合分析,建立了低槽-副高型、低涡-远距离台风型、两高切变型3类短时强降水概念模型;从物理量场来看,3类短时强降水均具有丰富的水汽和不稳定层结 (能量)、高于发生冰雹的0℃层高度、较厚的暖云厚度,且均发生在弱风切变环境中;低槽-副高型最为典型,其抬升凝结高度最高,500 hPa与850 hPa假相当位温差Δθse、抬升指数,K指数,对流有效位能量值最低,短时强降水发生频次高,1 h降水量大多在25 mm以内。低涡-远距离台风型水汽条件最好,深厚湿区、次天气尺度Ω系统和较低的抬升凝结高度使短时强降水发生范围最广,强度更强。两高切变型降水强度最大、持续时间最短并具有突发性, 其Δθse、抬升指数、K指数、对流有效位能最高,0~3 km垂直风切变最强,对流性特征明显,特别是强天气威胁指数接近300,强降水发生的同时往往伴有雷暴。Abstract: The statistical characteristics of short-time heavy precipitation vary in different areas. Based on thehourly automatic weather station precipitation data and NCEP reanalysis data with the resolution of 1°× 1° in Shaanxi, Gansu, Ningxia from May to September during 2005—2010, the statistical analysis are conducted to explore the spatial-temporal distribution of short-time heavy precipitation in different class, synoptic conceptual models and their features of physical parameter. The results indicate there are 4 active and 3 inactive areas of short-time heavy precipitation in Shan-Gan-Ning Region.Hourly precipitation above 80 mm could occur in both areas. Short-time heavy precipitation (over 30 mm per hour) is closely associated with special terrain such as wind ward slop of mountain and trumpet-shaped terrain. Short-time heavy precipitation is active in July and August, followed by June and September. The severe rainfall occurs mostly in late June and mid-August, and the cumulative frequency is slightly smaller in early August because of droughts season. Diurnal variation presents the bimodal distribution. Short-time heavy precipitation (over 30 mm per hour) shows the characteristic that severe precipitation tends to occur in the evening (2000—0800 BT). With the increase of precipitation intensity, that feature becomes more obvious. Spatial-temporal distribution features above are closely associated with the large-scale atmospheric circulation. All 3 kinds of synoptic conceptual model have common features in physical quantities filed: Ample of vapor, convective unstablestratification, instable energy, high 0℃ isotherm height, thick warm cloud layer, and weak wind shear. Despite common features, each model has its unique features.Trough and subtropical high pattern is the most typical type in Shan-Gan-Ning Region. This pattern has the highest value of LCL and lowest of Δθse(500 hPa minus 850 hPa), LI, K and CAPE, so the short-time heavy precipitation happens most frequently and the hourly precipitation is seldom more than 25 mm. Low vortex and typhoon far away pattern has the most favorable vapor condition and its deep wet area, sub-synoptic scale Ω system, lowest LCL results in broad precipitation areas and stronger precipitation. Shear between two high pressure pattern has the highest contribution of Δθse, LI, K, CAPE and strongest vertical wind shear (0—3 km), which leads to the most sever precipitation. Short-time heavy precipitation of this pattern occurs more suddenly and doesn't last long, when the SWEAT reaches near 300. It can also be found that the occurrence of short-time heavy precipitation is often accompanied by thunderstorm.
-
图 6 陕甘宁地区短时强降水概念模型 (绿色区域为短时强降水落区)(a) 低槽-副高型,(b) 低涡-远距离台风型,(c) 两高切变型
Fig. 6 The conceptual model of short-time heavy precipitation in Shan-Gan-Ning Region (area with short-term heavy precipitation is green)(a) trough and subtropical high pattern, (b) low vortex and typhoon far away pattern, (c) shear between two high pressure patterns
表 1 各类概念模型物理量平均值
Table 1 Average physical parameters of each short-time heavy precipitation conceptual model
物理量 低槽-副高型 低涡-远距离台风型 两高切变型 水汽总量/mm 58.23 64.72 56.31 700 hPa水汽通量散度/(10-7g/(cm2·hPa·s)) -6.23 -12.46 -8.55 500 hPa和850 hPa假相当位温差Δθse/℃ -5.64 -7.71 -10.62 500 hPa和850 hPa温度差ΔT/℃ -24.51 -26.38 -29.27 抬升指数/℃ -3.12 -4.03 -4.61 对流有效位能/(J·kg-1) 257.43 639.62 1019.76 K指数/℃ 36.47 36.25 38.83 0℃层高度/gpm 5513.81 5207.74 5381.32 抬升凝结高度/gpm 915.93 837.63 872.51 暖云层厚度/gpm 4597.88 4370.11 4508.81 0~3 km垂直风切变/s-1 0.0027 0.0023 0.0044 强天气威胁指数 242.62 233.59 295.62 -
[1] 杨金虎, 江志红, 王鹏祥, 等.西北地区东部夏季极端降水量非均匀性特征.应用气象学报, 2008, 19(1): 111-112. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20080118&flag=1 [2] 季晓玲, 桑建人, 马筛艳, 等.贺兰山东麓宁夏一次极值暴雨过程分析.气象科技, 2010, 30(3): 333-334. http://www.cnki.com.cn/Article/CJFDTOTAL-QXKX201003008.htm [3] 李明, 高维英, 杜继稳, 等.远距离台风影响下的陕西大暴雨分析.干旱区研究, 2011, 28(3): 514-515. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGQX201010002261.htm [4] 铃伟妙, 罗亚丽, 张人禾, 等.引发舟曲特大泥石流灾害强降雨过程成因.应用气象学报, 2011, 22(4): 386-387. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20110401&flag=1 [5] 马鹤年.高原东北侧暴雨期间的四股气流.陕西气象, 1979(6): 31-35. http://www.cnki.com.cn/Article/CJFDTOTAL-SXQI197906004.htm [6] 王式功, 杨德保, 张武, 等.甘肃河西中部"87.6"罕见暴雨成因分析.中国干旱, 1994, 14(2): 24-29. http://www.cnki.com.cn/Article/CJFDTOTAL-ZGSS402.003.htm [7] 白肇烨, 徐国昌, 孙学筠, 等.中国西北天气.北京:气象出版社, 1988:250-254. [8] 西北暴雨编写组.西北暴雨.北京:气象出版社, 1992:6-8. [9] 刘勇, 张科翔. 2002年6月8日佛坪突发性特大暴雨天气过程分析.应用气象学报, 2005, 16(1): 61-64. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20050108&flag=1 [10] 慕建利, 杜继稳, 张弘, 等.一次诱发山地灾害突发性暴雨数值模拟及诊断分析.气象, 2005, 31(12): 38-40. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200512007.htm [11] 武麦凤, 王旭仙, 孙健康, 等. 2003年渭河流域5次致洪暴雨过程的水汽场诊断分析.应用气象学报, 2007, 18(2): 226-229. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20070238&flag=1 [12] 李晓霞, 寿绍文, 张铁军, 等. "8.19"西北东部大到暴雨诊断分析和数值模拟.气象, 2006, 32(2): 84-86. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200602014.htm [13] 王劲松, 李耀辉, 康凤琴, 等.西北地区东部一次暴雨的数值模拟试验.高原气象, 2002, 21(3): 263-266. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200203005.htm [14] 王楠, 刘勇, 郭大梅.用多普勒雷达资料对一次区域性暴雨的中尺度分析.气象, 2007, 33(8): 32-34. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGQX200611001134.htm [15] 毕宝贵, 刘月巍, 李泽椿. 2002年6月8—9日陕南大暴雨系统的中尺度分析.大气科学, 2004, 28(5): 752-756. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK200405008.htm [16] 慕建利, 杜继稳, 梁生俊, 等.中β尺度系统造成的大暴雨过程数值模拟与诊断分析.气象, 2006, 32(8): 25-28. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200608003.htm [17] 陈静, 矫梅燕, 李川.青藏高原东侧一次β中尺度对流系统的数值模拟.高原气象, 2003, 22(增刊): 96-98. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX2003S1012.htm [18] 杨诗芳, 郝世峰, 冯晓伟, 等.杭州短时强降水特征分析及预报研究.科技通报, 2010, 26(4): 495-496. http://www.cnki.com.cn/Article/CJFDTOTAL-KJTB201004006.htm [19] 尹承美, 梁永礼, 冉桂平, 等.济南市区短时强降水特征分析.气象科学, 2010, 30(2): 263-266. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-SDKX201012001004.htm [20] 苏永玲, 何立富, 巩远发, 等.京津冀地区强对流时空分布与天气学特征分析.气象, 2011, 37(2): 181-183. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX201102008.htm [21] 陕西省减灾协会.陕西省重大自然灾害综合研究与防御对策.西安:陕西科学技术出版社, 1993:65-67. [22] 王政宇.喇叭口地形对降水的作用.气象, 1982, 8(1): 17-18. doi: 10.7519/j.issn.1000-0526.1982.01.007 [23] 卓嘎, 谢金南, 马镜娴.登陆台风与我国降水的统计关系.高原气象, 2000, 19(2): 260-264. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200002015.htm [24] 李岩瑛, 钱正安, 薛新玲, 等.西北干旱区夏半年深厚的混合层与干旱气候形成.高原气象, 2009, 28(1): 47-49. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200901006.htm [25] 雷雨顺.特大暴雨的夜间多发性.自然杂志, 1980, 3(10): 775-776. http://www.cnki.com.cn/Article/CJFDTOTAL-ZRZZ198010021.htm [26] Tang M C, Reiter E R. Plateau monsoons of the northern hemisphere: A comparison between North American and Tibet. Mon Wea Rev, 1984, 112: 617-620. doi: 10.1175/1520-0493(1984)112<0617:PMOTNH>2.0.CO;2 [27] 张养才, 叶一舫.中国亚热带西部山区夜雨特征的农业气候学研究.地理科学, 1994, 14(1): 31-34. http://www.cnki.com.cn/Article/CJFDTOTAL-DLKX199401004.htm [28] 井喜, 贺文彬, 毕旭, 等.远距离台风影响陕北突发性暴雨成因分析.应用气象学报, 2005, 16(5): 655-656. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20050584&flag=1 [29] 马鹤年.次天气尺度Ω系统和暴雨落区.暴雨文集.长春:吉林人民出版社, 1978: 171-176. [30] 刘建文, 郭虎, 李耀东, 等.天气分析预报物理量计算基础.北京:气象出版社, 2005:214-215.