基于常规气象观测、 浙江省自动气象站、 宁波多普勒雷达和凉帽山岛370 m高塔边界层资料, 对宁波市2012年7月7日(个例1)和2013年3月22日(个例2)两次冰雹过程进行了比较分析, 结果表明: 两次过程发生在不同季节和天气背景下, 个例1由强热对流单体所致, 个例2则是具有高架雷暴特征的移动性强对流带所造成。地面流场都显示: 雹暴前侧入流辐合带和后侧下沉气流辐散区相对雹暴中心位置变化不大, 两次过程前部冷出流边界前沿距离降雹中心约8~10 km及其后约4 km处形成了下沉尾涡。雹暴前侧入流区边界层主要表现为气压下降、 气流转向雹暴中心、 风速及辐合加大等; 而下沉辐散区则表现出天气要素的剧烈变化。个例1高塔处于冰雹前侧入流区, 边界层气象要素变化低层先于高层, 临近降雹时由于拖曳作用削弱了抽吸作用, 近地层各气象要素均有短时间的反向变化。个例2高塔处于低层入流区时, 风速增大也最先出现在塔层底部; 雹暴过境时, 冷高压出流造成高塔处边界层风向、 风速剧烈变化, 上下各层时间较一致。
Based on the data from the conventional meteorological observations, the automatic weather stations in Zhejiang province, the Ningbo Doppler radar and the 370 meters tower on the Liangmaoshan island etc., detailed comparison analysis was carried out on two hail cases occurred on 7 July 2012 (case 1) and 22 March 2013 (case 2) in Ningbo. The results show that the two cases happened under different synoptic backgrounds, with case 1 initialized from a strong thermal convectional cell, while case 2 developed from a moving convective zone with characteristics of elevated thunderstorms. The 2 cases displayed similar surface flow patterns, with the front inflow convergence zones and the rear divergence areas both relatively stable to the storm centers. The front outflow edges were found 8~10 km away from the hail-hit areas in both cases with sinking trail vortices about 4 km behind. The boundary layer of the front inflow zones primarily showed pressure dropping, air flow turning to the storm center, and increasing of both velocity and convergence intensity. Within the divergence areas, drastic meteorological element changes were observed. In case 1, the tower was in front of the hail storm inflow zone, the meteorological changes at the tower were observed at the lower levels prior to the higher levels. Also it showed a short time period of reversed changes of all elements right before hailfall, due to the downward air-flow dragging and weakening of air suction. In case 2, when the tower was in the lower inflow region, velocities were observed strengthened at the low levels first as well. When the hail storm went by, the boundary layer elements at the tower showed simultaneously abrupt changes as the result of cold outflows.
[1]Lemon R L, Doswell C A. Severe thunderstorm evolution and mesocyclone structure as related to tornadogenesis[J]. Mon Wea Rev, 1979, 107(9): 1184-1197.
[2]王秀明, 钟青, 韩慎友. 一次冰雹天气强对流(雹)云演变及超级单体结构的个例模拟研究[J]. 高原气象, 2009, 28(2): 352-365.
[3]冯晋勤, 俞小鼎, 傅伟辉, 等. 2010年福建一次早春强降雹超级单体风暴对比分析[J]. 高原气象, 2012, 31(1): 239-250.
[4]许新田, 王楠, 刘瑞芳, 等. 2006年陕西两次强对流冰雹天气程的对比分析[J]. 高原气象, 2010, 29 (2): 447-460.
[5]陈涛, 张芳华, 宗志平. 一次南方春季强对流过程中影响对流发展的环境场特征分析[J]. 高原气象, 2012, 31(4): 1019-1031.
[6]刘一玮, 寿绍文, 解以扬, 等. 热力不均匀场对一次冰雹天气影响的诊断分析[J]. 高原气象, 2011, 30(1): 226-234.
[7]樊李苗, 俞小鼎. 中国短时强对流天气的若干环境参数特征分析[J]. 高原气象, 2013, 32(1): 156-165, doi: 10.7522/j.issn.1000-0534.2013.00016.
[8]陈英英, 唐仁茂, 李德俊, 等. 利用雷达和卫星资料对一次强对流天气过程的云结构特征分析[J]. 高原气象, 2013, 32(4): 1148-1156, doi: 10.7522/j.issn.1000-0534.2012.00108.
[9]谈哲敏, 方娟, 伍荣生. Ekman边界层动力学的理论研究[J]. 气象学报, 2005, 63(5): 543-555.
[10]盛日锋, 王俊, 龚佃利, 等. 济南“7.18”大暴雨中尺度分析[J]. 高原气象, 2011, 30(6): 1554-1565.
[11]井喜, 李社宏, 屠妮妮, 等. 黄河中下游一次MCC和中-β尺度强对流云团相互作用暴雨过程综合分析[J]. 高原气象, 2011, 30(4): 913-928.
[12]苏爱芳, 银燕, 蔡淼. 夏末华北低槽尾部雹云的生成环境和结构特征[J]. 高原气象, 2012, 31(5): 1376-1385.
[13]戴建华, 陶岚, 丁杨, 等. 一次罕见飑前强降雹超级单体风暴特征分析[J]. 气象学报, 2012, 70(4): 609-627.
[14]吴乃庚, 林良勋, 冯业荣, 等. 2012年初春华南“高架雷暴”天气过程成因分析[J]. 气象, 2013, 39(4): 410-417.
[15]张备, 尹东屏, 孙燕, 等. 一次寒潮过程的多种相态降水机理分析[J]. 高原气象, 2014, 33(1): 190-198, doi: 10.7522/j.issn.1000-0534.2012.00171.
[16]王华, 孙继松, 李津. 2005年北京城区两次强冰雹天气的对比分析[J]. 气象, 2007, 33(2): 49-56.
[17]刘健文, 郭虎, 李耀东, 等. 天气分析预报物理量计算基础[M]. 北京: 气象出版社, 2005: 117-119.
[18]涂小萍, 姚日升, 漆梁波, 等. 浙江省北部一次灾害性大风多普勒雷达和边界层特征分析[J]. 高原气象, 2014, 33(6): 1687-1696, doi: 10.7522/j.issn.1000-0534.2013.00092.
[19]Browning K A, Foote G B. Airflow and hail growth in supercell storms and some implication for hail suppression[J]. Quart J Roy Meteor Soc, 1976, 102(433): 499-533.
[20]黄美元, 徐华英. 云和降水物理[M]. 北京: 气象出版社, 1999: 128-138, 173-177.
[21]Parker M D, Johnson R H. Simulated convective lines with leading precipitation. Part I: Governing dynamics[J]. J Atmos Sci, 2004, 61(14): 1637-1655.
[22]Ogura Y, Phillips N A. Scale analysis of deep and shallow convection in the atmosphere[J]. J Atmos Sci, 1962, 19(2): 173-179.
[23]叶家东, 史斌强. 积云对流中扰动压力效应的诊断分析[J]. 大气科学, 1987, 11(3): 320-330.
[24]夏文梅, 慕熙昱, 徐芬, 等. 南京地区初夏一次阵风锋过程的分析与识别[J]. 高原气象, 2009, 28(4): 836-845.