干旱气象
榦旱氣象
간한기상
GANSU METEOROLOGY
2014年
4期
622-628
,共7页
回流天气%低空急流%降水相态%温度廓线%诊断分析
迴流天氣%低空急流%降水相態%溫度廓線%診斷分析
회류천기%저공급류%강수상태%온도곽선%진단분석
return flow weather%low-level jet%precipitation phase%temperature profile%diagnostic analysis
利用常规观测资料、自动站资料、雷达及NCEP 1°×1°资料,在诊断2013年4月19日河北省一次回流多相态降水过程成因的基础上,总结了降雪漏报的原因。结果表明:冀中南降水区位于700 hPa切变线南侧、700 hPa西南低空急流与850 hPa东北风急流交汇处,暖湿空气在冷垫上爬升和急流的次级环流为降水提供了动力条件,低空急流为降水提供了水汽条件。整层大气可降水量及变化可作为降水预报的重要参考。对比分析雨区和雪区的温度廓线发现:通过温度平流分析温度的垂直分布和演变比单独分析温度特性层高度对于辨别降水相态更为可靠,而雷达风廓线资料可作为识别冷暖平流进而辨别大气温度层结变化的有益补充。本次降水相态预报出现偏差的主要原因是对温度垂直分布和演变判断不够准确。
利用常規觀測資料、自動站資料、雷達及NCEP 1°×1°資料,在診斷2013年4月19日河北省一次迴流多相態降水過程成因的基礎上,總結瞭降雪漏報的原因。結果錶明:冀中南降水區位于700 hPa切變線南側、700 hPa西南低空急流與850 hPa東北風急流交彙處,暖濕空氣在冷墊上爬升和急流的次級環流為降水提供瞭動力條件,低空急流為降水提供瞭水汽條件。整層大氣可降水量及變化可作為降水預報的重要參攷。對比分析雨區和雪區的溫度廓線髮現:通過溫度平流分析溫度的垂直分佈和縯變比單獨分析溫度特性層高度對于辨彆降水相態更為可靠,而雷達風廓線資料可作為識彆冷暖平流進而辨彆大氣溫度層結變化的有益補充。本次降水相態預報齣現偏差的主要原因是對溫度垂直分佈和縯變判斷不夠準確。
이용상규관측자료、자동참자료、뢰체급NCEP 1°×1°자료,재진단2013년4월19일하북성일차회류다상태강수과정성인적기출상,총결료강설루보적원인。결과표명:기중남강수구위우700 hPa절변선남측、700 hPa서남저공급류여850 hPa동북풍급류교회처,난습공기재랭점상파승화급류적차급배류위강수제공료동력조건,저공급류위강수제공료수기조건。정층대기가강수량급변화가작위강수예보적중요삼고。대비분석우구화설구적온도곽선발현:통과온도평류분석온도적수직분포화연변비단독분석온도특성층고도대우변별강수상태경위가고,이뢰체풍곽선자료가작위식별랭난평류진이변별대기온도층결변화적유익보충。본차강수상태예보출현편차적주요원인시대온도수직분포화연변판단불구준학。
There was an obvious precipitation process with the typical return flow on 19 April 2013 in Hebei Province,which was ac-companied with snow in the south and rain in the north of Hebei.It was the latest process with rain and snow conversion in the central and south of Hebei Province.Thus,based on the conventional observation data,the automatic meteorological station data,the radar data and the NCEP reanalysis data at 1°×1°spatial resolution,the missing reason of snow was investigated by analyzing the typical return flow precipitation process.The results showed that the precipitation process was mainly affected by the 500 hPa westerly trough, 700 hPa southwesterly wind jet,wind shear and 850 hPa northeasterly wind jet.The precipitation area just located in the south of the 700 hPa shear line and the intersection between the 700 hPa southwesterly wind jet and 850 hPa northeasterly wind jet.The warm moist southwesterly jet climbed on the cold pad of low level northeasterly jet,and its secondary circulation was helpful to the strong upward motion,and the 700 hPa low-level jet offered abundant water vapor for the precipitation,while return flow coming from the northeast of China was relatively dry.The whole atmosphere precipitable water vapor and its variation were considered as important reference in-dex for prediction.The main reason for forecasting deviation of precipitation phase was not accurate enough to determine the vertical distribution and evolution of temperature.It was found by contrast the temperature profiles over rain and snow areas that the lower tem-perature in south and center region dropped continually due to the influence of two cold airs from west and east paths,and then caused a widespread converting from rain to snow,but the temperature in the north region affected by weak warm advection was relatively high, which made precipitation phase to keep liquid all the time.That is to say,,the vertical distribution and evolution of temperature de-rived from temperature advection were more reliable to identify phase than the height of the characteristics temperature layer.The wind profile of radar should be useful supplemented to identify temperature advection and the atmospheric stratification change.