河套地区一次寒潮天气的环流形势分析

利用常规气象观测资料和Micaps提供的相关资料,对2009年9月19—20日在河套地区发生的寒潮天气的环流形势及物理量进行分析。分析表明:在寒潮爆发前期,500hPa系统,蒙古西部的冷中心强度≥-32℃,且温度场滞后于高度场,为冷空气爆发南下提供了最基本条件;700hPa河套地区及上游≥16m.s-1的西北风急流基本形成,等温线与等高线交角≥45°且10个纬距内有4条及以上等温线的密集区;850hPa河套地区有≥16℃的暖中心,高空槽前后的西北风速≥18 m.s-1,温度线与高度线的夹角>45°;地面蒙古气旋的暖性性质为寒潮爆发的前期提供了有利的热力条件,地面冷锋后部冷高压轴线接近南北向,且冷高压中心强度≥1040hPa,3h变压≥3hPa。

Analysis on Circulation Situation of a Cold Wave Weather in Hetao Area

Using the routine observational data and MICAPS related data, the circulation situation and physical quantity of cold wave weather on September 19-20, 2009 in Hetao area was analyzed. The results showed that in the early days of cold wave outburst, the cold center intensity in Mongolia west in 500hPa was greater than or equal to -32℃, moreover temperature field lagged behind height field, it provided basic condition for cold air erupted and moved south. The northwest wind jet stream that was greater than or equal to 16m·s^-1 in Hetao area and upstream in 700hPa was formed basically, the crossing angle of isotherm and contour line was greater than or equal to 45°, there are more than four isothermal in ten latitude distance as well. There are a warm center that was greater than or equal to 16℃ in Hetao area in 850hPa, the northwest wind was greater than or equal to 18 m·s^-1 in the front and back of upper trough, the intersection angle of temperature linear and height linear was greater than 45°, the warm Mongolia cyclone provided heating power condition for cold wave outburst, the axis direction of cold high pressure was near to NS-trending, the center intension of cold high pressure was greater than or equal to 1040hPa, variation air pressure of three hours was greater than or equal to 3hPa.