温室气体浓度增加情景下大西洋温盐环流的演变

牟林; 吴德星; 周刚; 陈学恩; 马超

温室气体浓度增加情景下大西洋温盐环流的演变

牟林^{1, 2,},
吴德星¹,
周刚³,
陈学恩¹,
马超¹

1.
中国海洋大学物理海洋实验室，山东青岛 266003
2.
德国Max-Planck气象研究所，德国汉堡 20146
3.
中国地质大学工程学院，湖北武汉 430074

基金项目:

国家自然科学基金项目 90411010

详细信息

作者简介:
牟林(1978-), 男, 博士, 主要研究方向为气候演变和近海环流.E-mail: lin.mu@dkrz.de

中图分类号: P731.27
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出版历程
- 收稿日期: 2006-06-20
- 刊出日期: 2007-01-25

Changes in Atlantic Thermohaline Circulation under Different Atmospheric CO₂ Scenarios

1.
Physical Oceanography Laboratory, Ocean University of China, Qingdao 266003, China
2.
Max-Planck Institute for Meteorology, Hamburg 20146, Germany
3.
Faculty of Engineering, China University of Geosciences, Wuhan 430074, China

摘要

摘要: 温室气体浓度增加(以CO₂为主) 引起的温盐环流演变在未来气候系统中扮演非常重要的角色.在最新的温室气体排放情景下, 利用基于德国马普气象研究所为IPCC第四次评估报告而最新发展的气候模式(ECHAM5/MPIOM), 对3种不同的温室气体排放假设(B1, A1B, A2) 进行了可靠的数值模拟.在此基础上, 就大西洋温盐环流和北大西洋深层水形成的变化, 以及北大西洋不同海区的温盐环流对温室气体浓度增加的响应, 对模拟结果进行了分析.研究揭示, 到21世纪末, 在3种CO₂排放情景下, 温盐环流强度分别减弱了4 Sv (1 Sv=10⁶ m³/s)、5.1 Sv、5.2 Sv, 大体相当于减弱了20%、25%、25.1%.由于全球变暖引起副极地海区表层海水变暖变淡, 拉不拉多海(Labrador Sea)和丹麦海峡(Denmark Strait)以南区域的深层对流有所减弱.而在格陵兰-冰岛-挪威海(GINS ea)的情况相反, 由于北大西洋暖流的增强, 通过法鲁海峡(Faro-Bank Channel)进入GIN海域的高盐水增加, 导致GIN海域上层盐度(密度)增加, 进而深层对流加强.在A1B情景下, 由于全球变暖北大西洋的深层水生成率从16.2 Sv降到了12.9 Sv.
- 温盐环流 /
- 温室气体 /
- 深层水
Abstract: Changes in the thermohaline circulation (THC) arising from the increase in the CO₂ concentration in the atmosphere will dominate the future climate regimes. In this paper, a new climate model developed at Max-Planck Institute for Meteorology is targeted at the variation of THC strength, the changes in North Atlantic deep water (NADW) formation and the regional responses of the THC in the North Atlantic to the increasing atmospheric CO₂. From 2000 to 2100, the increase in CO₂ (B1, A1B and A2) will have decreased the strength of THC by 4 Sv, 5.1 Sv and 5.2 Sv, respectively, or equivalently, reduced by 20%, 25% and 25.1% of the present THC strength. This research indicates that oceanic deep convective activity is significantly strengthened in the Greenland-Iceland-Norway (GIN) Seas owing to saltier (denser) upper oceans, but is weakened both in the Labrador Sea and in the south of the Denmark Strait region (SDSR) because of surface warming and freshening derived from global warming. The saltiness of the GIN Seas is mainly initiated by the increase in the saline North Atlantic inflow through Faro-Bank (FB) Channel. Under the scenario A1B, the deep water formation rate in the North Atlantic decreases from 16.2 Sv to 12.9 Sv with a corresponding increase in CO₂.
- thermohaline circulation (THC) /
- greenhouse gases /
- deepwater

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图 1 IPCC排放情景特别报告的CO₂情景浓度

Fig. 1. CO₂ concentrations of scenarios of IPCC (the intergovernmental panel on climate change) assessment report

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图 2 (a) 全球平均海表温度(SST) 和(b) 温盐环流(THC) 强度在不同的温室气体浓度增加情景下的随时间的变化曲线

Fig. 2. (a) Time series of global mean sea surface temperature and (b) the maximum value of the annual mean THC strength with global warming under the different scenarios

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图 3 A1B情景下20世纪(a, c) 和21世纪(b, d) 北大西洋的沿等密度面输运和穿越等密度面输运

UW代表THC的上层分支; DW+BW代表THC的下层分支; 箭头的方向代表沿等密度面的输运方向; 箭头旁边的数字是体积输运量(Sv).位于每个海区中心处的数字表示穿越等密度面的体积输运量(Sv), 负值表示上层分支轻的海水进入下层分支变为密度大的海水

Fig. 3. Isopycnal and diapycnal fluxes (Sv) under the A1B scenario

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