双月刊

ISSN 1006-9895

CN 11-1768/O4

2018年1月江苏两次暴雪过程积雪效率差异及其机理研究
作者:
作者单位:

1.南京信息工程大学 大气科学学院;2.江苏省气象台

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基金项目:

国家重点研发计划 2019YFC1510201,国家级大学生创新训练项目201810300051,国家科技支撑计划 2011BAK21B00,中国气象局预报员专项项目 CMAYBY2019-040,江苏省气象局科研项目 KM202001


On the snow accumulation efficiency difference during the two snowstorm events in Jiangsu in January 2018
Author:
Affiliation:

1.Nanjing University of Information Science&Technology;2.Jiangsu Meteorological Observatory

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    摘要:

    2018年1月3-5日江苏第一次暴雪过程中降雪量大、积雪效率偏低,而1月24-28日第二次暴雪过程降雪量小、积雪效率高。基于ERA-Interim再分析资料和中国气象局积雪、近地气温等观测资料,利用等熵大气质量环流理论从温度、水汽条件差异对2018年1月江苏两次暴雪过程积雪效率差异进行了深入分析。研究表明:(1)第一次过程前期,深厚且强盛的向极地暖支将大量暖空气输送至江苏南部,导致该地区整层增温;第二次过程中,低层强大的向赤道冷支输送使地面温度在整个降雪期间均低于0℃,低温条件使得积雪效率偏高;(2)第一次过程,江苏地区深厚、强盛的水汽质量辐合层配合大范围上升运动,将水汽携带至高层产生更大降雪量,低层经向水汽质量输送强,纬向水汽质量辐散较弱,使得近地面比湿相应增加,积雪效率偏低;第二次过程,低层深厚的水汽质量辐散层不利于水汽在江苏汇聚,低湿条件利于积雪累积,贡献于偏高的积雪效率。因此,异常强的经向干冷空气质量输送和弱的经向和纬向水汽质量输送引起的低温、低湿环境条件是造成第二次暴雪过程比第一次过程积雪效率偏高的主要原因。积雪效率与温度和湿度空间分布型的对比分析还表明:在相对高温、高湿的环境条件下,积雪效率对局地温度和湿度的响应更为敏感。

    Abstract:

    The first snowstorm event occurred in Jiangsu during January 3-5, 2018 had larger snowfall but lower snow accumulation efficiency, while the following second snowstorm event during January 24-28 had smaller snowfall but higher snow efficiency. Using the ERA-Interim reanalysis data and the observation data from the China Meteorological Administration, this study investigated the temperature and humidity conditions in these two snowstorm events and explored the underlying physical processes in the framework of isentropic atmospheric mass circulation. Main results are as follows: (1) The early stage of the first snowstorm event was characterized by higher temperature in the entire troposphere, which was attributed to a relatively deeper and stronger poleward warm air branch of isentropic atmospheric mass circulation to the south of Jiangsu, compared to the second snowstorm event. In contrast, in the second snowstorm event, the stronger equatorward cold air branch of isentropic atmospheric mass circulation resulted in the temperature lower than 0℃, which promoted the higher snow accumulation efficiency. (2) The deep water vapor convergence layer in lower isentropic layers collaborated with the wide range of ascending motions during the first snowstorm, and further brought lower-level water vapor to higher layer for the formation of larger snowfall. Larger meridional water vapor transport but weak zonal water vapor divergence in the low isentropic layers caused the near-ground specific humidity to increase significantly and thus contributing to the lower snow accumulation efficiency. However, in the second snowstorm event, there was a deep layer of water vapor divergence in the lower isentropic layers, which contributed to the larger snow accumulation efficiency. Therefore, colder and dryer conditions resulting from the abnormal meridional cold air transport and weak water vapor transport in both meridional and zonal directions are the key factors for the higher snow efficiency in the second snowstorm event. The comparison of spatial distribution of temperature and humidity with that of the snow efficiency further shows that the snow efficiency is more sensitive to the local temperature and humidity under the condition of high temperature and humidity.

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历史
  • 收稿日期:2021-04-15
  • 最后修改日期:2021-09-28
  • 录用日期:2022-01-14
  • 在线发布日期: 2022-02-28
  • 出版日期: