北京大学学报自然科学版 ›› 2021, Vol. 57 ›› Issue (5): 865-874.DOI: 10.13209/j.0479-8023.2021.062

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青藏高原对北大西洋深水形成影响机制的季节差异

邵星1, 杨海军2,†   

  1. 1. 北京大学气候与海?气实验室, 北京大学物理学院大气与海洋科学系, 北京 100871 2. 复旦大学大气与海洋科学系, 上海 200438
  • 收稿日期:2020-08-11 修回日期:2021-02-06 出版日期:2021-09-20 发布日期:2021-09-20
  • 通讯作者: 杨海军, E-mail: yanghj(at)fudan.edu.cn
  • 基金资助:
    国家自然科学基金(91737204, 41376007, 41725021)资助

Diverse Mechanism of the Tibetan Plateau Effect on the North Atlantic Deep Water Formation on Seasonal Timescale

SHAO Xing1, YANG Haijun2,†   

  1. 1. Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871

    2. Department of Atmospheric and Oceanic Sciences, Fudan University, Shanghai 200438

  • Received:2020-08-11 Revised:2021-02-06 Online:2021-09-20 Published:2021-09-20
  • Contact: YANG Haijun, E-mail: yanghj(at)fudan.edu.cn

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摘要：

利用耦合地球系统模式(CESM1.0), 通过对比有青藏高原的控制试验和无青藏高原的敏感性试验, 定性地分析青藏高原对不同季节北大西洋深水(NADW)形成的影响机制。研究结果表明, 青藏高原对NADW形成的影响机制因季节而异。移除青藏高原后, NADW形成将会减弱, 冷季(北半球10月—次年3月) NADW形成的显著减弱是由海洋表面净热通量显著增加引起的, 而暖季(4—9月)由于海冰大量融化引起淡水通量显著增加, 导致NADW形成的显著减弱。低分辨率耦合模式中, 青藏高原对NADW形成的这种季节性影响更加显著。不同季节青藏高原对NADW形成的影响机制主要区别在于, 青藏高原地形的存在使得冷季NADW形成区域的海洋表面失热增加, 在暖季造成该区域来自北部海冰的淡水输入减少。

关键词: 青藏高原, 北大西洋深水(NADW)形成, 季节尺度, 淡水通量, 热通量

Abstract:

Using the fully coupled model CESM1.0, the seasonal difference of the Tibetan Plateau (TP) effect on the North Atlantic deep water (NADW) formation mechanism is investigated qualitatively by comparing the sensitivity test without the TP and the control test with realistic topography. The result shows that the TP effect on the mechanism of the NADW formation varies with the seasons. The NADW formation decreases when the TP is removed, the significant increase of net surface heat flux in cold season (October to March of two consecutive years in the Northern Hemisphere) dominates the prominent decrease of the NADW formation, however, the significant increase of freshwater flux due to the mass of sea ice melting leads to the remarkable decrease of the NADW formation in warm season (April to September of the same year). The TP has a more significant effect on the NADW formation in the low resolution coupled model. The main difference of the TP effect on the NADW formation mechanism in different seasons is that the presence of TP topography increases the sea surface heat loss of the NADW formation region in cold season, also leads to decrease of the freshwater input from the northern sea ice in warm season.

Key words: Tibetan Plateau, North Atlantic deep water (NADW) formation, seasonal timescale, freshwater flux; heat flux

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