天津地区冰雹气候特征及影响路径研究

Research of climatic characteristics and influence path of hail in Tianjin

基于天津地区13个气象观测站1961-2020年冰雹观测资料,探讨了天津地区冰雹日数及持续时间的长期气候特征,在此基础上,利用构建的冰雹影响率评价指数,分析并划定了影响天津的冰雹移动路径。结果表明:天津地区冰雹空间上呈现北多南少的分布特征,北部蓟州冰雹日数年均值达到1.1 d。在年际变化上,1961-2020年天津冰雹日数呈现波动中下降的趋势,其中20世纪80年代为冰雹多发期,进入21世纪后冰雹明显减少;年内各月冰雹日数呈单峰型分布,集中出现在4~10月。近60年,天津地区冰雹过程持续时间呈现波动下降的趋势,但在2015年之后持续时间有一定程度的上升,表明在这段时间虽然冰雹频次有所降低,但强度有增强趋势。受午后热对流影响,冰雹天气集中出现在13~19时,其中16时发生冰雹概率最高;持续时间多为1~5min。影响天津地区的冰雹路径主要有4条,分别为西南路径、偏西路径、西北路径和东北路径。

Based on the hail observation data of 13 meteorological stations in Tianjin during 1961-2020,the long-term climatic characteristics of hail days and duration in Tianjin were discussed. On this basis,the hail transportation path affecting Tianjin was defined by using the constructed hail influence rate index. The results show that the hail is more likely to occur in the north part than in the south part over Tianjin,the annual average of hail days in Jizhou District is 1.1 d. For the interannual variability,the hail days in Tianjin from 1961 to 2020 show a decreasing trend in fluctuation and frequently happen in the 1980 s,while the hail days reduce significantly since21st century. The monthly change of hail days shows an unimodal distribution,the highest value appears from April to October. In recent 60 years,the duration of hail in Tianjin decreases in fluctuation but increases weakly since2015. It indicates that although the frequency of hail reduces during this time,the intensity shows an increasing trend. By the influence of afternoon thermal convection,the hail weather mainly occurs from 1300 to 1900 LST(local standard time),and the highest probability is 1600 LST. The duration of hail process in Tianjin is mostly 1~5 min.There are four main hail paths affecting Tianjin,including southwest path,westerly path,northwest path and northeast path.