干旱气象 ›› 2023, Vol. 41 ›› Issue (3): 380-389.DOI: 10.11755/j.issn.1006-7639(2023)-03-0380

• 论文 • 上一篇    下一篇

孟加拉地区夏季水汽变化及其与太平洋年代际振荡的联系

郭静妍1,2(), 肖栋2()   

  1. 1.中国气象科学研究院,北京 100081
    2.中国气象局上海城市气候变化与应对重点开放实验室,上海 200030
  • 收稿日期:2022-06-20 修回日期:2022-11-09 出版日期:2023-06-30 发布日期:2023-07-02
  • 通讯作者: 肖栋
  • 作者简介:郭静妍(1998—),女,硕士研究生,主要从事气候变率的研究。E-mail: guojingyannn@163.com
  • 基金资助:
    第二次青藏高原科学考察项目(2019QZKK0105);中科院先导专项项目(XDA20100300);国家自然科学基金项目(42175053)

Changes of summer water vapor in Bengal region and its linkage with the interdecadal Pacific oscillation

GUO Jingyan1,2(), XIAO Dong2()   

  1. 1. Chinese Academy of Meteorological Sciences, Beijing 100081, China
    2. Key Laboratory of Cities’ Mitigation and Adaptation to Climate Change in Shanghai, China Meteorological Administration, Shanghai 200030, China
  • Received:2022-06-20 Revised:2022-11-09 Online:2023-06-30 Published:2023-07-02
  • Contact: XIAO Dong

摘要:

孟加拉地区位于青藏高原与孟加拉湾、印度半岛与中南半岛的中间地带,是亚洲季风爆发率先影响的区域,孟加拉地区的水汽变化对亚洲南部以及东亚气候有重要的指示意义。采用1979—2020年欧洲中期天气预报中心ERA5再分析资料和美国国家海洋和大气管理局提供的海表面温度等资料,分析孟加拉地区夏季(6—9月)大气可降水量(Atmospheric Precipitable Water,APW)变化成因及其可能的物理过程。结果表明,孟加拉地区APW在亚洲南部同纬度最大,夏季APW占全年50%以上,且夏季平均APW呈显著增加趋势。从孟加拉地区4个边界整层的水汽收支和水汽收支垂直廓线来看,西边界与北边界的水汽收支趋势不利于该区域水汽增加,而东边界与南边界的水汽收支趋势利于该区域水汽增加。孟加拉地区夏季APW与太平洋年代际振荡(IPO)在年际和年代际尺度上均呈显著负相关。当IPO为正位相时,对流层低层赤道太平洋(赤道印度洋)盛行西风(东风)异常,对流层高层与之相反,表明印度洋与太平洋上的Walker环流减弱;对流层低层的赤道印度洋南北两侧呈Gill型反气旋环流异常,印度季风偏弱,阿拉伯半岛至孟加拉一带盛行西北风异常,西风气流不利于水汽向孟加拉地区输送,同时反气旋型环流伴随的下沉气流不利于该区域水汽汇聚,使得孟加拉地区APW减少。反之,当IPO为负位相时,则有利于孟加拉地区夏季APW增加。

关键词: 孟加拉地区, 大气可降水量, 水汽输送, 海表面温度, 太平洋年代际振荡

Abstract:

Located in the middle zone between the Tibetan Plateau and the Bay of Bengal, the Indian Peninsula and the Indo-China Peninsula, the Bengal region is the first region affected by the outbreak of the Asian monsoon. The change of water vapor in the Bengal region is of great significance to the climate of South Asia and East Asia. The causes and possible physical processes of the atmospheric precipitable water (APW) change in summer (June-September) in the Bengal region are analyzed using the ERA5 reanalysis data from the European Center for Medium-Range Weather Forecasts (ECMWF) and sea surface temperature data from the National Oceanic and Atmosphere Administration (NOAA) from 1979 to 2020. The results show that APW in the Bengal region is the largest at the same latitude in southern Asia. The summer APW accounts for more than 50% of the whole year, and the average summer APW presents a significant increase trend. According to the whole layer water vapor budgets and water vapor budget vertical profiles of the four boundaries of the Bengal region, the trends of the whole layer water vapor budgets of the eastern and southern boundaries are favorable to the increase of APW there, while the trends of the whole layer water vapor budgets of the western and northern boundaries are unfavorable to the increase of APW there. The summer APW in the Bengal region is negatively correlated with the interdecadal Pacific oscillation (IPO) on both inter-annual and inter-decadal scales. When the IPO is in its positive phase, in the lower troposphere, the westerly (easterly) wind anomaly prevails in the equatorial Pacific (equatorial Indian Ocean), while it is the opposite in the upper troposphere, indicating a weakening of the Walker circulation over the Indian and Pacific Oceans. The Gill-type anticyclonic circulation anomaly is observed in the lower troposphere in the north and south sides of the equatorial Indian Ocean. The Indian monsoon is weak, and a northwest wind anomaly prevails from the Arabian Peninsula to the Bengal region. The westerly airflow is not conducive to the transport of water vapor to the Bengal region, while the sinking airflow accompanying the anticyclonic circulation is not conducive to the convergence of water vapor in this region, resulting in the reduction of APW in the Bengal region. On the contrary, when the IPO is in a negative phase, it is favorable for the increase of APW in the Bengal region in summer.

Key words: the Bengal region, atmospheric precipitable water, water vapor transport, sea surface temperature, IPO

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