Journal of Arid Meteorology

Previous Articles     Next Articles

Characteristic of Phase Conversion and Its Causeon a Rainfall Process in Late Spring

ZHANG Nan1,2PEI Yujie1LIU Liang3ZHANG Yingxin1,2ZHANG Ye1   

  1. 1. Hebei Meteorological Observatory,Shijiazhuang 050021,China;
    2. Hebei Meteorological and Eco - Environment Monitoring Laboratory,Shijiazhuang 050021,China;
    3. North China Electric Power Research Institute Lt.d,Beijing 100045,China
  • Online:2014-04-18 Published:2014-04-18

一次晚春降水相态变化特征及成因

张南1,2裴宇杰1刘亮3张迎新1,2,张叶1   

  1. 1. 河北省气象台,河北 石家庄 050021;
    2. 河北省生态环境重点实验室, 河北 石家庄 050021;
    3. 华北电力科学研究院有限责任公司,北京 100045
  • 作者简介:张南(1980 - ),女,河北丰南人,硕士研究生,工程师,主要从事天气预报技术研究. E - mail:zn2000_nan@ aliyun. com
  • 基金资助:

    公益性行业(气象)专项(GYHY200906011)和河北省气象局暴雨创新团队项目共同资助

Abstract:

There was an obvious rainfall process with the typical return flow on April 19,2013 in the middle and south of Hebei Prov-
ince,which had a complicated conversion in precipitation patterns. The spatial distribution of precipitation patterns was rain in the
north and snow in the south of Hebei Province,which was rare in the history. Thus,based on the conventional observation data,auto-
matic meteorological observation data,Doppler radar data and reanalysis data from NCEP at 1° × 1° spatial resolution,the variation
characteristic of the precipitation phase in late spring and the cause of phase transformation were analyzed. The results showed that two
cold air from the east and west directions affected the central and south of Hebei Province. The cold air from the east path invaded
mainly below 850 hPa in earlier stage,while the cold air from the west path intensified temperature going down in the central and south
region with lower trough on 700 hPa moving to the east,which resulted in the precipitation types conversion in larger regions. The indi-
cation of the temperature above the ground 2 meter for the precipitation types conversions was limited because of the wide ranges of tem-
perature from -4 ℃ to 7 ℃,but the change of ground pressure was earlier than that of the temperature,thus the change of pressure
was more meaningful to forecast the temperature going down. The low - level jet on 700 hPa played a decisive role in the formation of
the middle - level warm layer,where the solid particles of rainfall could be melted to liquid. On the contrary,the rain converted into
the pure snow when the warm layer disappeared. The -2 ℃ isotherm of 925 hPa corresponded better with the snow area,so it was re-
liable to distinguish the phase of rainfall by the vertical profile of the temperature. Furthermore,the bright band of the 0 ℃ layer the
rain and snow mixture appeared over about 4. 7 km,and the time of quickly declining of the 0 ℃ layer height was corresponding with
the time of phase conversion of rainfall. Therefore,the change of the 0 ℃ layer height considered as an indicator of the phase conver-
sion of rainfall.

Key words:  return flow, precipitation phase, rain and snow conversion

摘要:

应用常规观测资料、自动站资料、雷达资料及 1° ×1°NCEP 再分析资料,对 2013 年 4 月 19 日河北省一次晚春回流降水相态变化特征及成因进行了分析。结果表明:河北中南部地区相继受东西2 股冷空气影响,前期东路冷空气从 850 hPa 以下入侵,之后西路冷空气随 700 hPa 高空槽东移加剧了中南部地区的降温,使大范围降水出现相态变化;地面温度对本次降水过程的雨雪相变指示性不大,但地面气压的变化早于地面温度,对预报具有一定的指示意义;700 hPa 低空急流对中空暖层的形成起决定作用,当暖层消失,降水相态完全转为降雪,925 hPa 上 - 2 ℃ 温度特征线与降雪区对应较好,通过温度的垂直结构来辨别相态更为可靠;雷达回波的 0 ℃层亮带出现高度在 4. 7 km 左右,其高度的快速降低与降水相态转变时间一致。

关键词: 回流, 降水相态, 雨雪转换

CLC Number: