全球变暖停滞背景下吐噶喇海峡黑潮减缓趋势及其动力机制

作者:刘昭君 发布日期:2021-09-26 阅读:1397

       近日,我室刘昭君副研究员在国际权威期刊Geophysical Research Letters发表学术论文。该成果为全球变暖停滞期间吐噶喇海峡黑潮减缓提供了实测证据,并揭示了北太平洋中高纬度风场对吐噶喇海峡黑潮叠加影响的动力机制。论文通讯作者为我室朱小华研究员,日本鹿儿岛大学Hirohiko Nakamura教授为论文合作者。

全球表面温度并不是单调递增的,于1998-2013年曾一度发生变暖停滞现象。近几年的研究结果表明,变暖停滞背景下黑潮的响应特征具有极强的区域性。该研究依据日本九州南部吐噶喇海峡的近九年走航ADCP测流数据及长期潮位计数据,通过建立黑潮流量和海峡两端水位差的经验关系,获得了1998-2013年期间吐噶喇海峡黑潮流量时间序列。研究发现在此期间黑潮减缓趋势显著,约每年减缓0.05 Sv (1 Sv = 106 m3 s-1),且黑潮流轴每年向北偏移0.31 km (Figure 1)。黑潮断面的CTD水文数据显示减缓期间黑潮离岸侧(奄美大岛侧)的密度跃层明显抬升,进一步分析发现这一过程主要是黑潮对风场变化的动力响应而非水团性质变化引发。北太平洋高纬度风场变化引起的海面高度正异常先通过Rossby wave传播至日本东海岸,进而通过Coastal trapped wave在日本沿岸顺时针方向的传播,影响吐噶喇海峡北侧海面高度异常。与此同时,北太平洋副热带逆流区的风场变化引起的海面高度负异常通过第二模态斜压Rossby wave传播至台湾东侧,随黑潮平流至吐噶喇海峡南侧(Figure 2)。最终,海峡南北两侧的负正海面高度异常致使黑潮呈减缓趋势。该机制的发现提升了我们对全球变暖停滞背景下北太平洋风场变化如何分区影响日本九州南部黑潮的认识。

  QQ截图20210926145659.jpg

Figure 1. Yearly mean (a) Kuroshio volume transport (KVT; dots) and (b) Kuroshio axis position (KAP; dots) in the Tokara Strait. The solid lines indicate the linear trend during 1998–2013 (statistically significant over the 90% confidence level).


QQ截图20210926145716.jpg

Figure 2. (a) Linear trends of wind stress curl (colors in units of 10-9 N m-3 year-1). Hatchings indicate statistical significance at the 90% confidence level. (b) Linear trends of zonal mean wind stress curl. Blue (red) dots denote negative (positive) trends above the 90% confidence level. (c) Linear trend of the sea surface height (SSH; mm year-1; color shading) derived from satellite data during 1995-2013. The linear trend in the global mean SSH (approximately 0.24 cm year-1) has been removed. Hatchings indicate statistical significance at the 90% confidence level. Gray contours indicate no trend. (d) Sea-level linear trend based on tide-gauge data at Naze (blue) and Nishinoomote (red). The global mean sea level has been removed. (e, f) Schematics of the sea-level changes in the North Pacific and around the Tokara Strait. In (f), the green line indicates the cruise line of the ferryboat ADCP in the Tokara Strait.

 

引用:Liu, Z.-J., Zhu, X.-H., Nakamura, H., Nishina, A., Wang, M., & Zheng, H. (2021). Comprehensive observational features for the Kuroshio transport decreasing trend during a recent global warming hiatus. Geophysical Research Letters, 48, e2021GL094169. https://doi. org/10.1029/2021GL094169


  • 卫星海洋环境动力学国家重点实验室

    © 2021卫星海洋环境动力学国家重点实验室 版权所有.
    浙ICP备10040255号-4      

  • 地址:杭州市保俶北路36号
    邮编:310012
  • 总机号码:+86-571-8196 3198
    传真:+86-571-8883 9374