Study On Mesoscale Structures Of Three-dimensional Dynamic And Thermodynamic Fields Of Mesoscale Convective Systems In Xinjiang

It is important to study the dynamic and thermodynamic mesoscale structure of convectiveprocess for the mechanism of convective process. The dual-Doppler radar is sufficient tostudy three-dimension structure of dynamic and thermodynamic process. It can observe moreexact and high spatial resolution data of the small and middle scale of precipitation systemstructure by dual-Doppler radar to embed study cloud and precipitation mesoscale physicalprocess. This paper analysis wind field, pressure and temperature field of a serve convectiveprecipitation on 7 August 2004 and a serve squall line on 26 June 2005 by two Band CDoppler radars which spaced 29km apart at Wulumuqi and Wujiaqu. The quality control andwind retrieval method reliability of dual-Doppler radar are also disused. The main concludesare discussed as follow:(1) The retrieval wind structure method which used to study the bai-u front storm rainfallcombined with the dynamic and thermodynamic retrieval method which bring forward byRoux to construct dual-Doppler radar dynamic and thermodynamic retrieval method ofconvective process by Band C national new period weather radar and the method have beentested.(2) From the case of dual-Doppler radar data quality at Xinjing, the two radial – twotangential dealiasing method is sufficient to the radial velocity dealiasing of two Dopplerradar at Wulumuqi and Wujiaqu. The position, intensity and structure of two radar echo areidentical. The data is reliable and is suitable to perform observe by dual-Doppler radar.(3) From the two cases above, we conclude that the choice of Cressman interpolationparameter effect on exact structure of wind field;The wind retrieval errors resulted from theradial velocity measurement errors are associated with their relative positions to the radars,however, such type of errors within 1 m s-1 on redial velocity would not change the majorshapes of the mesoscale wind structures. The wind field retrieval method is stable.(4) The severe convective rainfall on 7 August 2004 is the evolution from convective cellto convective band, the new cell is produced at the left side of the old one, and finallydeveloped as band-shape convective system(with 90km length) which was correspondingwith a convergence background combined by a branch of strong northeasterly wind and aweak westerly one, and updraft corresponded with strong echo. The different convectivebands actually had their independent wind structures respectively. Through dual Dopplerradar observation, it would be easier for us to analyze inside kinetic features of convectivesystem and therefore study the formation and development mechanism of precipitation.(5) The conditional instability of atmosphere stratification,low-level-convergence andrise in temperature triggered the severe squall line in Xinjiang on 26 June 2005. Different newechoes, generated continuously in the right of old echo, merged with old echo to form a squallline about 50km in northeast-southwest direction. In front of the squall line existed amesoscale convergence line. Merging processes are the important factors in the squall linedevelopment, and the convergence in low level promoted generation and development of newecho, and affected the combination of convective echo. Mature cells in squall line had somecharacteristics of super cell storm. Warm low-pressure in low level corresponded with strongecho and convergence region. Generally speaking, the temperature in region of updraft isrelative high.