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:短时强降水在陕什宁三省存在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类短时强降水慨念模型;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△θ_(sc)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△θ_(sc)、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。
The statistical characteristics of short-time heavy precipitation vary in different areas. Based on the- hourly automatic weather station precipitation data and NCEP reanalysis data with the resolution of 1°x1° in Shaanxi, Gansu, Ningxia from May to September during 2005--2010, the statistical analysis are con- ducted to explore the spatial-temporal distribution of short-time heavy precipitation in different class, syn- optic 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 associat- ed 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 be- cause of droughts season. Diurnal variation presents the bimodal distribution. Short time heavy precipitati- on （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. Spa- tial-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 va- por, 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 subtropi- cal high pattern is the most typical type in Shan-Gan-Ning Region. This pattern has the highest value of LCL and lowest of △θsc（500 hPa minus 850 hPa）, LI, K and CAPE, so the short-time heavy precipitation happens most frequent
出处
《应用气象学报》
CSCD
北大核心
2012年第6期691-701,共11页
Journal of Applied Meteorological Science
基金
国家科技支撑计划项目(2012BAH05B01)
关键词
短时强降水
时空分布
概念模型
物理量
short-time heavy precipitation
spatial-temporal distribution
conceptual model
physical pa-rameters
