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干旱区地理 ›› 2016, Vol. 39 ›› Issue (3): 521-529.

• 气候与水文 • 上一篇    下一篇

复杂地形条件下的降水相态预报指标研究

黄玉霞, 王宝鉴, 肖玮, 伏晶, 谭丹, 彭筱   

  1. 兰州中心气象台, 甘肃 兰州 730020
  • 收稿日期:2016-01-04 修回日期:2016-03-02 出版日期:2016-05-25
  • 作者简介:黄玉霞(1976-),女,甘肃兰州人,硕士,高级工程师,主要从事灾害性天气预报研究.Email:hyx_gsma@163.com
  • 基金资助:

    中国气象局气象关键技术集成与应用面上项目(CMAGJ2014M55);公益性行业(气象)科研专项(GYHY201206029)

Precipitation phase state forecasting indicators under the complex topography condition

HUANG Yu-xia, WANG Bao-jian, XIAO Wei, FU Jing, TAN Dan, PENG Xiao   

  1. Lanzhou Central Meteorological Observatory, Lanzhou 730020, Gansu, China
  • Received:2016-01-04 Revised:2016-03-02 Online:2016-05-25

摘要: 利用2003-2013年地面观测资料、探空资料及NCEP 1°×1°再分析资料,分析了近10 a甘肃省雨雪转换的时空分布特征,获得了复杂地形条件下相态转换的温度预报组合指标,结果表明:(1)雨雪相态转化主要发生在过渡季节的春季和秋季,占总次数的83.5%,空间上有三个高发区。(2)相态的转换发生在高原槽东移产生降水的环流形势下,通常500 hPa冷平流清晰并沿西北、西方、北方等3条路径影响甘肃。当沿西北路径移动时,高原槽主体深厚,冷平流强度最强,河东大部发生雨雪转换,当沿西方路径移动时,高原槽浅且位置偏南,北方冷空气较弱,仅高原边坡、陇中及陇东中南部出现转换。(3)T地面>3.0℃、T地面<-1.0℃、-1.0℃< T地面< 3.0℃是雨、雪、雨夹雪相态转换的前提条件,在此前提下获得了三类站点相态转换的不同层次温度组合指标,经检验,该指标预报效果较好。

关键词: 降水相态预报, 温度指标, 高原槽, 冷平流, 海拔高度

Abstract: Precipitation phase forecasting is particularly important during the transformation period from autumn to winter and winter to spring because the same magnitude of different precipitation phases can lead to marked differences. As the altitude differed obviously from east to west in Gansu Province, northwest China, precipitation phase forecasting became more difficult to judge with a unified index. Then it is very necessary to determine the forecasting indexes of precipitation phase according to altitude. By using the surface observation data, sounding data and 1°×1° NCEP reanalysis data from 2003 to 2013, the temporal and spatial distribution characteristics of precipitation phase transformation were analyzed for nearly 10 years in Gansu Province and temperature forecast indexes of the phase transformation were got under the condition of complex topography. Results reveal as follows:(1) in Gansu, there was three high-incidence areas for the precipitation phase transformation that mainly occurred in the transformation seasons, spring and autumn, accounting for 83.5% of the total.(2) The phase transformation usually occurred when the circulation of plateau trough moved eastward and produced precipitation. Generally, obvious cold advection on 500 hPa along the northwest or west or north paths influenced Gansu. When moving along the northwest path, the plateau trough was deep and the cold advection the strongest, the rain and snow conversion occurred in most Hedong region of Gansu Province;when moving along the western path, plateau trough was shallow and more southerly, phase conversion occurred only in central and southern Longdong area of Gansu.(3) The arrival time of cold advection near surface was a good forecasting index for the conversion occurrence time. When cold advection intensity was less than -5×10-5℃·s-1 on 700 hPa and -10×10-5℃·s-1 on 850 hPa, cold advection control zone will occur phase transformation. It is very helpful for forecasters to predict accurately whether it is the direct solid precipitation or conversion of liquid to solid in the actual business.(4) Except for cold advection, the combination of temperature at different levels was a more important factor that affecting the phase transformation. Ground temperature higher than 3.0℃, lower than -1.0℃, between -1.0℃ and 3.0℃ were the prerequisite for rain, snow and sleet phase transformation, respectively. Under this precondition:for a region of altitude less than 1500 m, it tended to snow when temperature was less than or equal to -3.0℃ at 850 hPa and less than or equal to -6.0℃ at 700 hPa, to sleet when temperature was between -3.0℃ and 2.5℃ at 850 hPa and between -6.0℃ and -3.0℃ at 700 hPa;for a region of altitude between 1500 m and 2000 m, it tended to snow when temperature was less than or equal to -7.0℃ at 700 hPa, to sleet when temperature was between -7.0℃ and -4.0℃ at 700 hPa;for a region of attitude more than 2000 m, it tended to snow when temperature was less than or equal to -1.0℃ at 700 hPa, to sleet when temperature was between -1.0℃ and 2.0℃ at 700 hPa. Upon examination, the indexes had good forecast results.

Key words: precipitation phase forecasting, temperature indexes, plateau trough, cold advection, altitude

中图分类号: 

  • P426.613