WRF模式对一次中低纬降雪天气的数值模拟分析
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摘要
基于NCEP再分析资料,选取中低纬度滇西南普洱作为研究区域,利用WRF模式模拟2013年12月一次小雪及雪后霜冻天气过程,通过模式输出资料对降雪天气进行诊断分析。结果表明:此次降雪过程的主要影响系统为南支槽,降雪天气发生在强冷空气形成的低空切变线北部;该过程大气为稳定性层结并具有湿斜压性,垂直剖面上MPV1正值中心向下延伸至500 h Pa,此高度以下MPV1以弱的正值为主;干冷空气的输送造成湿斜压性增强,MPV2负值中心达到-0.2PVU,同时配合南支槽提供的水汽条件形成了此次降雪天气。南支槽东移出境后,大气湿斜压性减弱(MPV2负值中心-0.05PVU);前期大气湿斜压性造成局地平流降温,与其后的对流稳定性及高层冷空气的向下输送引起辐射降温,共同造成了较强的混合型霜冻。WRF模式对中低纬滇西南降雪天气过程的范围、时间及雪后强降温天气有较好的模拟效果。
Based on intensive observations,NCEP reanalysis data and FNL data,Choosing southwestern of Yunnan as the study area; A snowfall and frost process during 15—17 December 2013 in southwestern of Yunnan was simulated by WRF model( Weather Research Forecasting),The analysis of the output data indicates that the WRF model can make good simulation about the snowfall distribution and time and temperature field. Main conclusions are as follows: The process of main influencing system for the south westerly trough and severe cold air,the area of snowfall in the north of the location of low level wind shear. The atmospheric possess the characteristic of steady and moist baroclinity in the process. The positive region of MPV1 down into 500 h Pa,but MPV1 is weak positive under the 500 h Pa,So it is concluded that the atmospheric is steady. That increased moist baroclinity because of dry cold air. At the same time,MPV2 is negative and approached-0. 2 PVU. Based on this condition with plentiful vapor by the south westerly trough,the snowfall process appeared in southwestern of Yunnan. MPV2 is reduced to about-0. 05 PVU when the south westerly trough have already moved to east of Yunnan. The temperature advection led to drop in temperature in the baroclinic atmosphere and the combination of the stable stratification and the downward transport of cold air due to upper troposphere have formed severe frost in puer.
Based on intensive observations,NCEP reanalysis data and FNL data,Choosing southwestern of Yunnan as the study area; A snowfall and frost process during 15—17 December 2013 in southwestern of Yunnan was simulated by WRF model( Weather Research Forecasting),The analysis of the output data indicates that the WRF model can make good simulation about the snowfall distribution and time and temperature field. Main conclusions are as follows: The process of main influencing system for the south westerly trough and severe cold air,the area of snowfall in the north of the location of low level wind shear. The atmospheric possess the characteristic of steady and moist baroclinity in the process. The positive region of MPV1 down into 500 h Pa,but MPV1 is weak positive under the 500 h Pa,So it is concluded that the atmospheric is steady. That increased moist baroclinity because of dry cold air. At the same time,MPV2 is negative and approached-0. 2 PVU. Based on this condition with plentiful vapor by the south westerly trough,the snowfall process appeared in southwestern of Yunnan. MPV2 is reduced to about-0. 05 PVU when the south westerly trough have already moved to east of Yunnan. The temperature advection led to drop in temperature in the baroclinic atmosphere and the combination of the stable stratification and the downward transport of cold air due to upper troposphere have formed severe frost in puer.
引文
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[2]宫德吉,李彰俊.低空急流与内蒙古的大(暴)雪[J].气象,2001,27(12):3-7.
[3]王东勇,刘勇,周昆.2004年末黄淮暴雪的特点分析和数值模拟[J].气象,2006,32(1):30-35.
[4]李兆慧,王东海,王建捷,等.一次暴雪过程的锋生函数和次级环流分析[J].高原气象,2011,30(6):1505-1515.
[5]孙艳辉,李泽椿,寿绍文.2007年3月3—5日辽宁省暴雪和大风天气的中尺度分析[J].气象学报,2012,70(5):936-948.
[6]章国材.美国WRF模式的进展和应用前景[J].气象,2004,30(12):27-31.
[7]陶健红,张新荣,张铁军,等.WRF模式对一次河西暴雪的数值模拟分析[J].高原气象,2008,27(1):68-75.
[8]范元月,汤剑平,徐双柱.一次湖北暴雪天气的诊断与模拟[J].气象科学,2010,30(1):111-115.
[9]Isidora Jankov at al.An investigation of IHOP convective system predictability using a matrix of 19 WRF members[C].84th AMS Annual Meeting,Seattle,U.S.A.Jan.10-15,2004.
[10]Moriss Weisman at a1.Real-time explicit convective forecasts using the WRF model during the BAMEX field program[C].84th AMS Annual Meeting,Seattle,U.S.A.Jan.10-15,2004.
[11]Jason C.Knievel at a1.The diurnal mode of summer rainfall across the conterminous United States in 10-km simulation by the WRF model[C].84th AMS Annum Meeting,Seattle,U.S.A.Jan.10-15,2004.
[12]沈桐立,曾瑾瑜,朱伟军,等.2006年6月6—7日福建特大暴雨数值模拟和诊断分析[J].大气科学学报,2010,33(1):14-24.
[13]王咏青,宋天元,梁驹,等.西太平洋台风季节预报的数值模拟[J].大气科学学报,2012,35(1):24-31.
[14]吴国雄,蔡雅萍.湿位涡和倾斜涡度发展[J].气象学报,1995,53(4):387-404.
[15]王宏,王万筠,余锦华,等.河北东北部暴雪天气过程的湿位涡分析[J].高原气象,2012,31(5):1 302-1 308.