低空急流对中国褐飞虱重大北迁过程的影响

低空急流是褐飞虱远距离迁飞的理想空中通道之一,为了揭示低空急流对褐飞虱北迁的动力作用机制,在全面分析2007年中国褐飞虱虫情资料的基础上,筛选出典型个例,结合相应的气象背景资料,对低空急流在褐飞虱北迁中的动力影响进行了系统的研究.研究表明:(1)低空急流作为一种大尺度天气系统,对2007年中国褐飞虱的重大北迁产生了重要的影响,这种影响体现在对虫源输送和降虫上;(2)低空急流的时空分布和强度变化对褐飞虱降虫时段、降虫范围、降虫量多少和主降虫区位置的选择有重要的影响;(3)逆推轨迹计算的结果显示:迁入主降区的褐飞虱是由低空急流输送的,这与其动力作用相吻合;(4)低空急流中的下沉气流对降虫区分布有着决定性的影响.

Influence of Low-level Jets on the great events of BPH's migration northward in China

Low level jet (LLJ) is an ideal passageway for the long-distance migrations of Nilaparvata lugens (Stal)′s populations. In order to explore the effect of LLJ on BPH′s migrations northward, we have conducted a synthetic analysis of the Chinese BPH′s lighting catches in 2007 and done some case studies in combination with the respective weather data. Our results indicate: (1) the LLJ as a large-scale weather system in Eastern Asia, played an important role in the great migrations northward of Chinese BPH′s populations in 2007 linking the pest sources and the destination of the migrant populations; (2) the tempo-spatial distribution and strength change of LLJ had a significant impact on the landing times, landing scopes, landing heads of BPH′s populations, and the selection of the main landing regions; (3) the prediction of that the brown planthoppers immigrated into the main landing regions carried by LLJ by a trajectory-backward approach is consistent with LLJ dynamic explanation; (4) the downstream of LLJ played a key role in the distribution of the BPH′s landing areas.