内蒙古大兴安岭林区雷击火灾气候成因分析

利用常规天气图、数值预报产品、卫星云图以及溃变理论的预报工具V-3θ图,对2005年6月30日至7月2日发生在青藏高原东北侧甘肃省区域性持续暴雨天气过程进行了诊断应用综合分析.结果表明:副热带高压西伸北抬外围西南风气流控制青藏高原东北侧,当东北低涡、西风带的冷空气与西南风交汇时,触发强对流;850～200hPa有深厚的水汽层;700 hPa稳定的低涡切变为暴雨提供了强烈持续的辐合上升运动;卫星云图表明持续性暴雨由多个相继生消的中尺度对流系统影响造成的.基于溃变理论的预报方法在西北区域性持续暴雨的起报、结束及落区有很好的预测能力.

Climatic Cause Analysis of Forest Fires Induced by Lightning Strikes in Daxinganling Forests

The meteorological and lightning strike data, as well as forest fire data from 1981 to 2004 are used to study the effects of climatic conditions on the occurrence of forest fires induced by lightning strikes in the forest region of Daxinganling Mountain, Inner Mongolia, and the climatic causes of the frequent lightning induced forest fires are analyzed. The results reveal that: (1) the occurrence frequency of lightning induced forest fires in Daxinganling had a increasing trend and occurred mostly in the period from 12 May to 16 July, 10:00 to 17:00; (2) the occurrence of lightning induced forest fires has close relations with temperature increase, especially the increase of temperature from May to July and ground temperature; (3) the gradual decrease of precipitation and relative humidity led to greater drought damages and more lightning induced forest fires after 1999; (4) the leading climatic cause of the frequent occurrence of lightning induced forest fires in Daxinganling Mountain are the drier and warmer climate and frequent extreme climatic events.