气象与环境学报
氣象與環境學報
기상여배경학보
JOURNAL OF METEOROLOGY AND ENVIRONMENT
2014年
4期
26-33
,共8页
汪靖%赵玉洁%吴振玲%蔡子颖
汪靖%趙玉潔%吳振玲%蔡子穎
왕정%조옥길%오진령%채자영
天津地区%强阵风%混合层%动量下传%数值模拟
天津地區%彊陣風%混閤層%動量下傳%數值模擬
천진지구%강진풍%혼합층%동량하전%수치모의
Tianjin area%Strong gusts%Mixed layer%Downward propagation of momentum%Numerical simulation
利用NCEP再分析资料和常规地面观测资料,分析混合层的建立对2012年3月23日天津地区强阵风天气过程的影响机理。结果表明:强气压梯度和强变压梯度的共同动力作用是地面强阵风形成的背景条件。强阵风出现在午后气温较高、湿度较低且地面气压较低的时段。午后深厚混合层内的干热对流使高空急流北侧下沉气流将动量下传至对流层中层后向近地面层进一步有效下传,导致地面阵风增大。深厚混合层的建立也是地面强阵风形成的一个重要原因。WRF模拟结果表明,局地混合层强度差异使高空动量下传产生局地差异,可能是天津各地区阵风强度存在空间差异的重要原因。
利用NCEP再分析資料和常規地麵觀測資料,分析混閤層的建立對2012年3月23日天津地區彊陣風天氣過程的影響機理。結果錶明:彊氣壓梯度和彊變壓梯度的共同動力作用是地麵彊陣風形成的揹景條件。彊陣風齣現在午後氣溫較高、濕度較低且地麵氣壓較低的時段。午後深厚混閤層內的榦熱對流使高空急流北側下沉氣流將動量下傳至對流層中層後嚮近地麵層進一步有效下傳,導緻地麵陣風增大。深厚混閤層的建立也是地麵彊陣風形成的一箇重要原因。WRF模擬結果錶明,跼地混閤層彊度差異使高空動量下傳產生跼地差異,可能是天津各地區陣風彊度存在空間差異的重要原因。
이용NCEP재분석자료화상규지면관측자료,분석혼합층적건립대2012년3월23일천진지구강진풍천기과정적영향궤리。결과표명:강기압제도화강변압제도적공동동력작용시지면강진풍형성적배경조건。강진풍출현재오후기온교고、습도교저차지면기압교저적시단。오후심후혼합층내적간열대류사고공급류북측하침기류장동량하전지대류층중층후향근지면층진일보유효하전,도치지면진풍증대。심후혼합층적건립야시지면강진풍형성적일개중요원인。WRF모의결과표명,국지혼합층강도차이사고공동량하전산생국지차이,가능시천진각지구진풍강도존재공간차이적중요원인。
Based on the NCEP reanalysis data and conventionally observational data,influence mechanism of estab-lishment of mixed layer (ML)on a strong gust weather process on March 23,2012 in Tianjin was diagnosed and simulated .The results show that joint action of strong pressure and allobaric gradient in front of cold high is synop-tic background of formation of surface strong gusts.Strong gusts occur in the period of higher surface temperature, lower pressure and low relative humidity.In the afternoon,the hot and dry convection within the deep ML makes the upper-level momentum that is in the north side of upper jet easily propagate to ground layer effectively,which leads to enhancement of surface gusts.The establishment of deep ML is another reason leading to formation of strong surface gusts.Results simulated by a WRF model suggest that local intensity of the ML may cause local differences of downward propagation of momentum,which may be the important factor causing spatial differences of gusts intensity over Tianjin.