近10a房山区暖季强对流天气特征分析

Characteristics of Severe Convective Weather in Warm Season in Fangshan District of Beijing in Recent 10 Years

【目的】为了解房山区暖季强对流天气的时空分布特征和环流形势,提高强对流天气的预报准确率和防灾减灾服务水平。【方法】利用2012—2021年房山区46个自动站常规观测资料、灾情数据、探空资料及北京观象台S波段雷达数据,对房山区强对流天气的特征进行分析。【结果】近10 a强对流天气总体呈现波动上升态势;7月强对流天气发生频次最高,6、8月次之;短时强降水发生频次比雷雨大风、冰雹高;强对流天气日变化呈“午后”型特征,短时强降水09—14时、20时—次日03时为高发时段;雷雨大风17—22时最频发;冰雹高峰时段在15—17时。不同强对流天气的空间分布差异明显,受地形、水汽条件影响,短时强降水在山区及沿山一带多;雷雨大风空间分布不均,山区及南部平原多;冰雹山区多、平原少。西来槽型、蒙古低涡低槽型、东北冷涡型环流背景下发生强对流天气的频次高,多以西北路、西南路、偏西路径影响。【结论】研究成果可为房山区精细化预报预警提供参考,有助于提升全区应对灾害性天气的能力。

To understand the spatial and temporal distribution characteristics and circulation situation of severe convective weather in Fangshan District of Beijing in warm season,and to improve the prediction accuracy of severe convective weather and the effectiveness of disaster prevention and mitigation services,this paper analyzes the characteristics of severe convective weather including short-time severe precipitation,thunderstorm gales,and hail in Fangshan District on the basis of the conventional observation data from 46 automatic weather stations in Fangshan District from 2012 to 2021,as well as disaster data,sounding data,and S-band radar data from Beijing Observatory.The results denote a generally fluctuating upward trend of severe convective weather over the past decade in Fangshan District.July has the highest frequency of severe convective weather,followed by June and August.Short-time severe precipitation occurs more frequently than thunderstorm gales and hail.Diurnal variation of severe convective weather is characterized by peaks appearing in the “afternoon” period,with short-time severe precipitation observed mostly from 9∶00 to 14∶00 and from 20∶00 to the next 03∶00,thunderstorm gales mostly from 17∶00 to 22∶00,and hail mostly from 15∶00 to 17∶00.The spatial distribution of different types of severe convective weather varies significantly.Influenced by topography and moisture conditions,short-time severe precipitation is more frequent in mountainous areas and along mountains.Thunderstorm gales exhibit an uneven spatial distribution,with a majority occurring in mountainous areas and the southern plain.Hail is more common in mountainous areas but less in plain areas.Severe convective weather occurs more frequently under the circulation background of the westerly trough,Mongolian low vortices,and Northeast cold vortices,and mainly takes the northwest,southwest and westward pathways.These findings could provide a reference for the refined forecasting and early warning of severe convective weather in Fangshan District.