南京大学学报(自然科学版) ›› 2024, Vol. 60 ›› Issue (2): 267–275.doi: 10.13232/j.cnki.jnju.2024.02.008

• • 上一篇    

海洋性大陆地形对夏季季节内振荡的影响：基于2020年9月个例的数值模拟分析

孔钰博1, 周逸豪2, 汪曙光1()   

  1. 1.中尺度灾害性天气教育部重点实验室，南京大学大气科学学院，南京，210023
    2.科罗拉多州立大学大气科学系，Fort Collins，CO, 80523，美国
  • 收稿日期:2024-02-01 出版日期:2024-03-30 发布日期:2024-03-29
  • 通讯作者: 汪曙光 E-mail:wangsg@nju.edu.cn
  • 基金资助:
    国家自然科学基金(42275055)

The influence of topography of Maritime Continent on the boreal summer intraseasonal oscillation: Numerical simulation analysis based on a case in September 2020

Yubo Kong1, Yihao Zhou2, Shuguang Wang1()   

  1. 1.Key Laboratory of Mesoscale Severe Weather, Ministry of Education, and School of Atmospheric Sciences, Nanjing University, Nanjing, 210023, China
    2.Department of Atmospheric Sciences, Colorado State University, Fort Collions, CO, 80523, USA
  • Received:2024-02-01 Online:2024-03-30 Published:2024-03-29
  • Contact: Shuguang Wang E-mail:wangsg@nju.edu.cn

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摘要：

海洋性大陆（Maritime Continent，MC）是夏季大气季节内振荡（the Boreal Summer IntraSeasonal Oscillation，BSISO）传播的必经途径，而MC对于BSISO结构和传播产生的重要的影响机制很不清楚.针对此问题，利用高精度数值模式对一次BSISO事件展开数值模拟试验研究.选取2020年8-9月的一次BSISO事件，利用高精度数值模式WRF （Weather Research and Forecasting model）对本次BSISO过程进行了近一个月的数值模拟.发现WRF控制试验合理模拟出与再分析资料中相近的北传低层风场以及明显具有BSISO特征的西北?东南倾斜的雨带，并合理地捕捉了本次BSISO事件的传播特征和平均状态.为了研究MC地形对本次事件传播和强度的影响，在WRF模式中去除了MC地区的地形，开展了敏感性试验.在去除地形的敏感性试验中，BSISO低空风加强，传播更加平滑，整体降水幅度增加，而在岛屿上水汽大幅增加，降水量减少.在地形高度为零的情况下，纬向平流大大增强，从而增强了海上对流，促进了BSISO的加强和传播.此数值模拟试验研究揭示了MC地形对BSISO降水结构、传播和幅度的影响.

关键词: 夏季季节内振荡, 海洋性大陆, 地形, 对流允许数值试验

Abstract:

Maritime Continent (MC) may interfere the propagation of BSISO (the Boreal Summer IntraSeasonal Oscillation). In this study,the Weather Research & Forecast (WRF) model is used to simulate the BSISO event observed in the area around MC during the period of August-September,2020. To study the influence of the topography of the MC on the propagation and intensity of this BSISO event,the topography of the MC is flattened in the WRF model,and a sensitivity experiment is conducted for comparison with the control experiment. The WRF control simulation shows the low?level wind similar to this in ERA5,as well as a northwest ? southeast tilted rain band as observed BSISO,indicating that the control experiment reasonably captures the mean state and propagation characteristics of this BSISO event. Eliminating the topography around the MC region in the sensitivity experiment results in stronger low?level wind and smoother propagation. There is a significant increase in water vapor and a decrease in precipitation around the MC islands. The zonal advection is greatly enhanced,thus enhancing the convection over the ocean and promoting propagation of this BSISO. The results suggest substantial impact of the MC island on the structure and propagation of the BSISO.

Key words: the Boreal Summer IntraSeasonal Oscillation, Maritime Continent, topography, cloud?permitting simulation

中图分类号: 

  • P444

图1

WRF模式中模拟区域的地形高度（填色图，单位：m）The red polygon indicates the areas of MC islands."

图2

观测（左列）、CNTL（中列）和No Topography试验（右列）在模拟期间的每五天平均的降水（填色图，单位：mm·d-1）和850 hPa风场距平场（矢量图，单位：m·s-1）"

图3

(a)观测，(d) CNTL，(g) No Topography试验在模拟期间的平均降水（填色图，单位：mm·d-1）；(b, e, h)和(c, f, i)分别为整层积分可降水量（填色图，单位：kg·m-2）和850 hPa风场（填色图，单位：m·s-1）(d) CNTL, (g) No topography； (b, e, h) are the same as in (a, d) and (g), but for averaged CWV (unit: kg·m-2),and (c, f, i) are the same as in (a, d) and (g), but for averaged wind at 850 hPa (unit: m·s-1), respectively"

图4

观测/再分析的0°~5°N平均日降水量（填色图，单位：mm·d-1）和850 hPa纬向风异常（等值线图，单位：m·s-1）时间?经度平均图.(a, c, d)分别为观测、CNTL和No Topography试验, (b, e, f)分别为5°~10°N的观测、CNTL和No Topography试验(e) CNTL, and (f) No Topography are the time?longitude diagrams of 5°~10°N"

图5

印度洋（左列）和MC（右列）的平均日降水量（填色图，单位：mm·d-1）和850 hPa纬向风异常（等值线图，单位：m·s-1）时间?纬度平均图， (a， b) (c， d) (e， f)分别为观测、CNTL和No Topography试验"

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