利用Micaps、物理量场剖面及海岛自动站等同步资料,对2009年l1月8～12日发生在河北区域性大暴雪高影响天气过程进行诊断分析.结果表明,大暴雪成因为3个不同时空尺度系统影响所致:8日降雨与强锋区弱切变南压及前期大雾抬升有关；9～ 10日暴雪是在天气尺度锋区的特定环流背景下,不同层面的温、湿场的“三支”气流辐合区恰好覆盖河北东部；11 ～12日中-大雪为环流快速调整后新生低槽东移所致；物理量诊断分析表明,9～10日石家庄地区强降雪时段850 hPa以下为下沉气流即升压降雪,渤海至太行山区偏东风和比湿大值区从8日持续到10日;11 ～12日新一轮低值系统垂直速度大值区中心为-10.0 hPa/h,12h后倾45°,中心值为-7.0hPa/h,明显系统降雪时比湿中心高度达600 hPa,移到河北东部降雪时高度回落至700 hPa,与850 hPa的高比湿区形成上下叠加的形式,并随着系统快速东移入海,到20:00河套冷空气已进入太行山区西部降雪逐渐停止,低值系统迅速东移至华北东部出现中-大雪天气.华北东部降雪前渤海大干16 m/s偏东风维持时间大于18h,950 hPa以下渤海中心区域主导风向水汽输送对强降雪落区动态变化具有指示意义;相对不同地区衍生的灾害性天气与持续降雪、持续低温及地形有关.%A regional snow storm in Heibei on November 8-12, 2009 was analyzed with Micaps, physical field profile and synchronous data from island stations. The results showed that the storm was caused by factors in three different spatial and temporal scales, rain on November 8 was caused by the southward movement of weak shear in the strong frontal zone and fog lifted early on; snow storm on November 9-10 was due to the specific circulation context of synoptic-scale frontal zone, convergence zone of three air currents from different levels of temperature and humidity which just covered east of Hebei; snow during November 11-12 was caused by eastward movements of new trough generated when circulation was quickly adjusted. As indicated by the physical analysis, during heavy snowfall in Shijiazhuang region on November 9 -10, air below 850 hpa was downdraft, i. e. snow from increased air pressure, and high-u region of easterly from Bohai Sea to Taihang Mountains and specific humidity lasted from 8th to 10th. During November 11 - 12 new low-pressure air reached maximum central vertical velocity of -10.0 hpa/H, and 12 hours later moved backward by 45 °, with central value of -7. 0 hPa/ H. The specific humidity center reached height of 600 hPa during obvious systematic snow. The height fell to 700 hpa when it moved to east Hebei and snow started, and formed a dual-system with high specific humidity region of 850 hpa, and it moved east to the sea rapidly with the system. Al 20:00, the cold air from the loop region entered west of the Taihang Mountains and the snow gradually stopped. And the low-value system rapidly moved eastward to east of North China and caused snow. Before the snow in east of Nurth China, easterly of North China with velocity over 16 m/s lasted over 18 hours- Water vapor transport of direction of major wind in central Bohai Sea region below 950 hpa has indicative significance of the dynamics in snowfall zones. Hazardous weather derived of different regions was caused by continuous snow, low temperature and specific terrain.
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