Controls on turbulent mixing on the West Antarctic Peninsula shelf
Controls on turbulent mixing on the West Antarctic Peninsula shelf
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DOI：
10.1016/j.dsr2.2017.02.011
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发表时间：
2017-05-01
影响因子：
3
通讯作者：
Inall, Mark E.
中科院分区：
文献类型：
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作者：
Brearley, J. Alexander;Meredith, Michael P.;Inall, Mark E.
西南极半岛的海洋-大气热收支部分受控于温暖的环极深水（CDW）层（位于200 m以下）到南极地表水（AASW）的向上热通量，AASW是一种季节性变化很大的水体。CDW的上升流和混合影响该区域海冰的形成，并通过其营养物质的输送影响生物生产力和生态系统的功能。在这项研究中，2.5年的时间序列的声学多普勒海流剖面仪（ADCP）和电导率-温度-深度（CTD）的数据被用来量化的diapycnal扩散系数kappa和垂直热通量Q之间的界面CDW和AASW。在研究期间，估计平均向上热通量为1 W m（-2），最大热通量发生在冬季固定冰消失后不久，此时水柱首次暴露于风应力，而没有被盐度强烈分层。冬季和夏季之间的混合机制的差异进行了研究。虽然潮汐驱动的混合在研究现场发生全年，但可能是相对较弱的，一个强大的逆时针极化近惯性能量（和剪切）的增加是在快速无冰季节观察到，这表明风暴对海洋表面的直接影响是负责大部分观察到的混合在现场。鉴于过去30年来该区域海冰持续时间迅速减少，可能正在向越来越多的风主导的混合状态转变。
The ocean-to-atmosphere heat budget of the West Antarctic Peninsula is controlled in part by the upward flux of heat from the warm Circumpolar Deep Water (CDW) layer that resides below similar to 200 m to the Antarctic Surface Water (AASW), a water mass which varies strongly on a seasonal basis. Upwelling and mixing of CDW influence the formation of sea ice in the region and affect biological productivity and functioning of the ecosystem through their delivery of nutrients. In this study, 2.5-year time series of both Acoustic Doppler Current Profiler (ADCP) and conductivity-temperature-depth (CTD) data are used to quantify both the diapycnal diffusivity kappa and the vertical heat flux Q at the interface between CDW and AASW. Over the period of the study, a mean upward heat flux of similar to 1 W m(-2) is estimated, with the largest heat fluxes occurring shortly after the loss of winter fast ice when the water column is first exposed to wind stress without being strongly stratified by salinity. Differences in mixing mechanisms between winter and summer seasons are investigated. Whilst tidally-driven mixing at the study site occurs year-round, but is likely to be relatively weak, a strong increase in counterclockwise-polarized near-inertial energy (and shear) is observed during the fast-ice-free season, suggesting that the direct impact of storms on the ocean surface is responsible for much of the observed mixing at the site. Given the rapid reduction in sea-ice duration in this region in the last 30 years, a shift towards an increasingly wind-dominated mixing regime may be taking place.