河南省冰雹时空分布及天气形势特征

Temporal and Spatial Distribution and Weather Situation Characteristics of Hail in Henan Province

利用河南省121个气象台站1971—2010年共40a的冰雹资料,应用统计学方法,分析了河南省冰雹日的年际、月际和日变化特征,以及降雹的落区和范围等空间分布特征等,结果表明:河南省冰雹的年际变化较不稳定,20世纪80年代到90年代中期冰雹日出现较多,到21世纪初又出现一个小高峰,2006年之后则保持较低值;每年4—8月为河南省冰雹多发期,而冰雹在一天之内绝大部分发生在午后到傍晚,这是由形成冰雹的热力条件决定的。40a间冰雹主要发生在河南省中北部、西部和西南部山区,而在东部和东南部的平原地区冰雹发生次数较少。通过对1999—2010年45个冰雹日天气形势的分析发现,河南省易产生冰雹的4种主要天气形势分别为西北气流型、东北冷涡型、华北冷涡型和低槽型,西北气流型造成的冰雹日为最多,低槽型冰雹日最少,不同天气形势背景下的降雹落区有较大差异。

Using statistical methods, the 40 years＇ data of 121 stations from 1971 to 2010 are analyzed to reveal the characteristics of hail in Henan province and get annual, monthly and daily features with temporal and spatial distribution of hail falling area and range. The result shows an instability of an nual feature. There were more hail days from 1980s to mid-1990s, a small peak appeared at the begin- ning of 21 century while low value after 2006. The hail frequently-occurring stage in one year is from A- pril to August and that in one day is from afternoon to evening, which depends on thermal condition of forming hail. During the 40 years, the hail falls mainly occur in north-center, west and southwest mountain areas in contrast with that happens in plain areas in the east and southeast of Henan province. By analyzing weather situation of 45 hail days during 1999 to 2010, four weather patterns in Henan province are mainly studied, which are northwest air current type, northeast cold vortex type, north China cold vortex type and trough type. The result shows that the hail days caused by northwest air current type appears the most while the least trough type, and different circulation background could cause difference hail falling area.