Greater Role of Geostrophic Currents in Ekman Dynamics in the Western Arctic Ocean as a Mechanism for Beaufort Gyre Stabilization
Greater Role of Geostrophic Currents in Ekman Dynamics in the Western Arctic Ocean as a Mechanism for Beaufort Gyre Stabilization
复制标题
地转流在北冰洋西部埃克曼动力学中的更大作用作为波弗特环流稳定机制
DOI：
10.1002/2017jc013282
复制
发表时间：
2018
影响因子：
3.6
通讯作者：
Zhao Jinping
中科院分区：
文献类型：
--
作者：
Zhong Wenli;Steele Michael;Zhang Jinlun;Zhao Jinping
在1992年至2014年期间，使用了七种不同的方法，在有和没有包括地转流的情况下，探索了北冰洋西部的埃克曼动力学。结果表明，近几年(2003-2014年)，当大洋Beaufort Gyre(BG)在该地区旋转时，表层地转流一直在增加，并且比Ekman层的速度强得多。与以前不考虑地转流的迭代方法相比，包括地转流在内的新方法得到了更接近实际的埃克曼泵送速度，因此在2003-2014年期间，高估了BG中心区域的埃克曼泵送速度高达52%。当BG像近年来看到的那样旋转时，地转流变得更强，这往往会改变冰洋应力，并缓和加拿大盆地由风驱动的埃克曼辐合。这是我们已经确定的一种机制，它在稳定埃克曼趋同方面发挥着重要的作用，因此近年来在稳定BG方面发挥着越来越大的作用。这一机制可以用来解释三种情景，它们描述了风强迫、海冰运动和地转流变化的相互作用，这些变化控制了1992-2014年间BG中部Ekman动力学的可变性。结果还揭示了加拿大盆地南部和北部以及楚科奇深海平原的几个上升区，这些地区可能在这些地区的物理和生物过程中发挥着重要作用。
Seven different methods, with and without including geostrophic currents, were used to explore Ekman dynamics in the western Arctic Ocean for the period 1992–2014. Results show that surface geostrophic currents have been increasing and are much stronger than Ekman layer velocities in recent years (2003–2014) when the oceanic Beaufort Gyre (BG) is spinning up in the region. The new methods that include geostrophic currents result in more realistic Ekman pumping velocities than a previous iterative method that does not consider geostrophic currents and therefore overestimates Ekman pumping velocities by up to 52% in the central area of the BG over the period 2003–2014. When the BG is spinning up as seen in recent years, geostrophic currents become stronger, which tend to modify the ice‐ocean stress and moderate the wind‐driven Ekman convergence in the Canada Basin. This is a mechanism we have identified to play an important and growing role in stabilizing the Ekman convergence and therefore the BG in recent years. This mechanism may be used to explain three scenarios that describe the interplay of changes in wind forcing, sea ice motion, and geostrophic currents that control the variability of the Ekman dynamics in the central BG during 1992–2014. Results also reveal several upwelling regions in the southern and northern Canada Basin and the Chukchi Abyssal Plain which may play a significant role in physical and biological processes in these regions.