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Lanzhou University (2015)

Analysis of Characteristics of Rainstorm in Tengger Desert and Numerical Simulation Research

朱岩

Titre : Analysis of Characteristics of Rainstorm in Tengger Desert and Numerical Simulation Research

Auteur : 朱岩

Grade : Master’s Theses 2015

Université : Lanzhou University

Résumé partiel
By using data from mutiple sources, the climatic background of precipitation in Tengger Desert was briefly introduced first. Then, the causes and characterisitics of two major rainstorm processes taken place in Jul,2012 were compared and analyzed from aspects of circulation background, water vapor, dynamic and thermal conditions. Afterwards, mesoscale filtering was performed according to Barnes’s filter operator. Combined with the scale-separated vorticity equation, the interaction of large scale and mesoscale fields and its impetus on the mesoscale systems we re thus analyzed as well as the relationship between Mesoscale thermal circulation and rainstorm was discussed. At last, sensitivity tests of initial field wave filtering were performed in virtue of WRF model, it preliminarily studied the relative contribution of large scale and mesoscale fields to rain and the sensitivity of rain simulation depending on them. Main conclusions summarized as follows :(1)Characteristics analysis of precipitation for years suggests that the precipitation amount and yearly average days of rainstorm in Tengger Desert decrease from southeast to northwest. The most concentrated months for rainstorms are from June to September. Rainstorms have becoming more frequent since 1990s and the interannual distribution of precipitation has also been homogenized as well as the stability has been increased during the past half century.(2)An analysis of two typical rainstorm processes revealed that they were intermittent frontal precipitation by the first type of slow cold front and mixed one of frontal and convective precipitation by the second type of fast cold front respectively, which differed in circulation situation, water vapor, mesoscale convective system, dynamic and thermal conditions. However, they were all caused by the joining of swelling subtropical high and Westerly disturbance. Water vapor was input into region of two deserts mainly from north, east and south boundaries, among which the north and the east boundary got persistent input with greater net income, while the south and the west boundary received water vapor only before and after rainstorm with less net income. The intensity change of the apparent heat source and moisture sink corresponded well with rainstorm process and reached its peak when rainstorm became most intensive

Mots clés : Rainstorm ;Tengger Desert ;Characteristics Analysis ;Numerical Simulation ;Scale interaction ;Mesoscale circulation ;

Présentation (CNKI)

Page publiée le 16 avril 2022