白背飞虱重大迁入过程的大气动力背景

为了揭示白背飞虱迁入的大气动力背景,为其灾变预警奠定气象学基础,根据2003年全国69个植保站提供的白背飞虱虫情资料,在ArcGIS9.0支持下对该年我国白背飞虱的时空分布规律进行了地学分析。利用MM5中尺度数值预报模式和由PCVSAT系统接收的气象数据对2个典型的白背飞虱南、北迁降落过程的大气背景进行了数值模拟和客观分析,模拟和分析结果表明:(1)850hPa等压面上气压场的配置及其随时空的演变是控制和影响白背飞虱迁入的最重要的大气环流因素。(2)850hPa高度上的偏南气流有利于白背飞虱种群的北迁,925hPa等压面上的偏北气流有利于其南迁,这两个高度上风场的气旋式风向切变区有利于白背飞虱的起飞迁出,反气旋式切变区有利于其迁入降落。(3)降水对白背飞虱的降落有着十分重要的动力胁迫作用,但其在北迁降落过程中的作用明显强于南迁。(4)垂直气流场中强下沉气流可迫使白背飞虱大量降落,表明气流胁迫是风载迁飞性害虫灾变性迁入的一个极其重要的大气动力机制。

Analysis of the atmospheric dynamical backgrounds for the great immigration events of white back planthopper (Sogatella furcifera)

In order to reveal the atmospheric dynamic backgrounds of white back planthopper(WBPH),Sogatella furcifera,immigrations and establish the meteorological substructure of its catastrophes forewarning,based on the information of WBPH's investigations of 69 plant protection stations covered the most of Chinese rice-growing areas in 2003,Chinese tempo-spatial patterns of WBPH's populations was analyzed topographically under the software assistance of ArcGIS9.0.According to this analysis,2 typical great immigrating events were selected.The observational meteorological data and T213 numerical simulation products covering these processes were obtained from the data accepted by a PCVSAT(PC Vary Small Aperture Terminal) station.These data were input into a model,MM5 3.2(The Fifth-Generation Mesoscale Model for version 3.2),and a set of atmospheric dynamical fields during these migrating and landing processes were simulated numerically and analyzed objectively.The results showed as followed:(1) The most important factor of atmospheric general circulation controlled and influenced the immigration of WBPH's populations was the patterns and the tempo-spatial changes of potential height field on 850hPa isobaric surface.(2) There were relative coincident air streams with a northern exposure on 850hPa isobaric surface during the migrations northward of WBPH and there were concurrent airflows with a southern exposure on 925hPa isobaric surface during the migration southward.The regions with cyclonic shears of wind directions were advantageous to the taking-off and emigrating of the pest and the regions with anticyclonic shears of wind directions were favorable to the immigrating and landing on 850hPa or 925hPa.(3)The rainfall played an important dynamical threatening role in the landing processes of WBPH's populations.Its effect in the landing processes of migration northward was stronger remarkably than the landing processes of migration southward.(4) The strong subsiding airflow on the vertical velocity field could compel WBPH's populations to land cosmically.It testified that vertical airflow threatening is a principal atmospheric dynamical mechanism of the catastrophic immigrations of windborne pests.