双月刊

ISSN 1006-9895

CN 11-1768/O4

不同强度环境垂直风切变影响下热带气旋外核区冷池特征
作者:
作者单位:

1.漳州市气象局;2.南京信息工程大学气象灾害教育部重点实验室、中国气象科学院灾害天气国家重点实验室

作者简介:

通讯作者:

基金项目:

国家自然科学基金


Characteristics of Cold Pools in the Outer Core of Tropical Cyclones in Different Vertical Wind Shear Magnitudes
Author:
Affiliation:

1.Key Laboratory of Meteorological Disaster of the Ministry of Education, Nanjing University of Information Science and Technology、State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences;2.Zhangzhou Meteorological Bureau

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
    摘要:

    本文基于高分辨率数值模式模拟结果分析了不同强度的环境垂直风切变影响下热带气旋外核区近地面冷池特征。结果表明:外核区对流型和非对流型冷池在不同切变环境中表现出相似的特征。两类冷池均伴随局地位温、相当位温和水汽混合比的降低和近地面高压扰动,冷池厚度通常低于400m,平均强度4~6m/s,均远小于中尺度系统冷池,其中非对流型冷池的厚度和强度显著大于对流型冷池,表明外核区不同类型的冷池强度不仅和位温扰动有关,还取决于冷池厚度;冷池内普遍存在下沉运动,对流型冷池中向下垂直质量输送约为非对流冷池的两倍;下沉运动导致冷池局地高压的主要原因为云下降水粒子的蒸发冷却和雨滴拖曳作用,对流云中的凝结潜热释放则不利于地面高压发展,其中对流型冷池中次云层蒸发冷却和降水拖曳作用较强,导致该类冷池地面增压也较大。不同强度的环境垂直风切变对不同类型冷池特征也有一定影响。弱切变环境中外核区冷池多表现为尺度较小且分布离散的对流型冷池,随切变增强,冷池总数目和对流型冷池数目减少,而尺度较大且多位于层云降水区域的非对流型冷池增多,同时厚度加深、强度增强。环境风切增大还导致对流型和非对流型冷池造成的局地辐散出流均有所减弱但气旋式流速增强。

    Abstract:

    The characteristics of cold pools in the outer core of tropical cyclones under vertical wind shear of different magnitudes are investigated based on high-resolution idealized numerical simulations. The results suggest that the convective and non-convective cold pools in the outer core exhibit similar characteristics in different vertical wind shear magnitudes. Both two types of cold pools exhibit potential temperature, equivalent potential temperature, water vapor mixing ratio deficits and positive pressure perturbations. The depth of cold pools in the outer core of tropical cyclones is mostly less than 400 m, and the average strength is approximately 4~6 m/s, which is much smaller than that in mesoscale convective system. The depth is deeper and the intensity is also stronger significantly for non-convective cold pools, indicating that the intensity of different types of cold pool is not only related to the potential temperature perturbation, but also depends on its depth. The cold pools are caused by widespread convective-scale downdrafts, and the downward vertical mass transport in convective cold pools caused by stronger downdrafts is almost twice that of non-convective ones. Budgets of surface perturbation pressure induced by downdrafts indicate that subcloud evaporational cooling and water loading are conducive to high pressure near the surface in cold pools, while in-cloud warming due to latent heat release leads to a pressure decrease. Moreover, the greater effects of precipitation drag and subcloud evaporation in convective cold pools result in more significant pressure increasement than that in non-convective cold pools. The features of both types of cold pools also varies with the increase in the shear value. There are mostly micro-scale and discrete convective cold pools in the weak-shear environment. As shear increases, the total number of outer-core cold pools and the frequency of convective cold pools decreases while the non-convective ones with larger range and mostly linked to dissipated convection increases, deepen and intensify, in addition. There are weaker outflow but stronger cyclonic velocity caused by both two types of cold pools with the shear magnitude increased.

    参考文献
    相似文献
    引证文献
引用本文
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2021-11-17
  • 最后修改日期:2022-03-12
  • 录用日期:2022-03-30
  • 在线发布日期: 2022-04-01
  • 出版日期: