This study investigates the effect of ocean dynamics on the tropical climate response to localized radiative cooling over three northern extratropical land regions using hierarchical model simulations that vary in the degree of ocean coupling. Without ocean dynamics, the tropical climate response is independent of the extratropical forcing location, characterized by a southward tropical precipitation shift with a high degree of zonal symmetry, a reduced zonal sea surface temperature gradient along the equatorial Pacific, and the eastward-shifted Walker circulation. When ocean dynamical adjustments are allowed, the zonal-mean tropical precipitation shift is damped primarily via Eulerian-mean ocean heat transport. The oceanic damping effect is strongest (weakest) for North Asian (American) cooling, associated with the largest (smallest) Eulerian-mean ocean heat transport across the equatorial Pacific. The cross-equatorial ocean heat transport in the Pacific is anchored to the North Pacific subtropical high, the response of which can be inferred from the corresponding slab ocean simulations. Hence, the slab ocean simulations provide useful a priori prediction for oceanic damping efficiency. Ocean dynamics also modulates the spatial pattern of climate response in a distinct manner depending on the zonal distribution of imposed forcing. North Asian forcing induces a pronounced eastern equatorial Pacific cooling extending to the western basin, accompanying the westward shifted Walker circulation. European forcing causes cooling confined to the eastern equatorial Pacific and strengthens the Walker circulation. The tropical precipitation response in these two cases exhibits large zonal variations with a high degree of equatorial symmetry, being essentially uncorrelated with the corresponding slab ocean simulations. By contrast, North American forcing induces a sufficiently strong inter-hemispheric contrast in the tropical Pacific SST response, due to the relatively weak oceanic damping effect, producing a weaker but spatially similar tropical response to that in the slab ocean simulation. This study demonstrates that the effect of ocean dynamics in modulating the tropical climate response depends on the extratropical forcing location. The results are relevant for understanding the distinct climate response induced by aerosols from different continental sites.

本研究使用不同海洋耦合程度的分层模型模拟，研究海洋动力学对三个北温带陆地区域局部辐射冷却的热带气候响应的影响。在没有海洋动力学的情况下，热带气候响应与温带强迫位置无关，其特征是具有高度纬向对称性的热带降水南移，沿赤道太平洋的纬向海表温度梯度减小，以及向东移动的沃克环流. 当允许海洋动态调整时，纬向平均热带降水变化主要通过欧拉平均海洋热传输而受到抑制。北亚（美洲）冷却的海洋阻尼效应最强（最弱），与穿过赤道太平洋的最大（最小）欧拉平均海洋热传输有关。太平洋的跨赤道海洋热传输锚定于北太平洋副热带高压，其响应可以从相应的板片海洋模拟中推断出来。因此，板状海洋模拟为海洋阻尼效率提供了有用的先验预测。海洋动力学还以不同的方式调节气候响应的空间模式，具体取决于施加强迫的纬向分布。北亚强迫导致赤道东部太平洋明显变冷，并延伸到盆地西部，伴随着向西移动的沃克环流。欧洲强迫导致仅在赤道东太平洋变冷，并加强了沃克环流。这两种情况下的热带降水响应表现出较大的纬向变化，具有高度的赤道对称性，与相应的板片海洋模拟基本不相关。相比之下，由于相对较弱的海洋阻尼效应，北美强迫在热带太平洋 SST 响应中引起了足够强的半球间对比，产生了与板片海洋模拟中较弱但空间相似的热带响应。这项研究表明，海洋动力学对热带气候响应的调节作用取决于温带强迫位置。这些结果有助于理解来自不同大陆地点的气溶胶引起的不同气候响应。与相应的板状海洋模拟基本上不相关。相比之下，由于相对较弱的海洋阻尼效应，北美强迫在热带太平洋 SST 响应中引起了足够强的半球间对比，产生了与板片海洋模拟中较弱但空间相似的热带响应。这项研究表明，海洋动力学对热带气候响应的调节作用取决于温带强迫位置。这些结果有助于理解来自不同大陆地点的气溶胶引起的不同气候响应。与相应的板状海洋模拟基本上不相关。相比之下，由于相对较弱的海洋阻尼效应，北美强迫在热带太平洋 SST 响应中引起了足够强的半球间对比，产生了与板片海洋模拟中较弱但空间相似的热带响应。这项研究表明，海洋动力学对热带气候响应的调节作用取决于温带强迫位置。这些结果有助于理解来自不同大陆地点的气溶胶引起的不同气候响应。由于相对较弱的海洋阻尼效应，产生了与板状海洋模拟中较弱但空间相似的热带响应。这项研究表明，海洋动力学对热带气候响应的调节作用取决于温带强迫位置。这些结果有助于理解来自不同大陆地点的气溶胶引起的不同气候响应。由于相对较弱的海洋阻尼效应，产生了与板状海洋模拟中较弱但空间相似的热带响应。这项研究表明，海洋动力学对热带气候响应的调节作用取决于温带强迫位置。这些结果有助于理解来自不同大陆地点的气溶胶引起的不同气候响应。