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首页> 外文期刊>Journal of Physical Oceanography >The Mean Along-Isobath Heat and Salt Balances over the Middle Atlantic Bight Continental Shelf
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The Mean Along-Isobath Heat and Salt Balances over the Middle Atlantic Bight Continental Shelf

机译：中大西洋海岸线大陆架上平均沿等温线的热量和盐分平衡

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摘要

The mean heat and salt balances over the Middle Atlantic Bight continental shelf are investigated by testing the hypothesis that surface fluxes of heat or freshwater are balanced by along-isobath fluxes resulting from the mean, depth-averaged, along-isobath flow acting on the mean, depth-averaged, along-isobath temperature or salinity gradient. This hypothesized balance is equivalent in a Lagrangian frame to a column of water, for example, warming because of surface heating as it is advected southward along isobath by the mean flow.rnMean depth-averaged temperatures increase from north to south along isobath at a rate of 2℃ (1000 km)~(-1) at midshelf, which is consistent with the hypothesized balance and mean surface heat flux estimates from the 50-yr NCEP Reanalysis. However, mean surface heat flux estimates from the higher-resolution 20-yr Objectively Analyzed Air-Sea Fluxes (OAFlux) reanalysis are too small to balance the along-isobath heat flux divergence implying a cross-shelf heat flux convergence. It is unclear which surface heat flux estimate, NCEP or OAFlux, is more accurate. The cross-shelf heat flux convergence resulting from the mean cross-shelf circulation is too small to balance the along-isobath heat flux divergence.rnMean depth-averaged salinities increase from north to south along isobath at a rate of 1 (psu) (1000 km)~(-1) at midshelf. Mean precipitation and evaporation rates nearly balance so that the net freshwater flux is too small by more than an order of magnitude to account for the observed along-isobath increase in salinity. The cross-shelf salt flux divergence resulting from the mean cross-shelf circulation has the wrong sign to balance the divergence in the along-isobath salt flux. These results imply there must be an onshore "eddy" salt flux resulting from the time-dependent current and salinity variability.rnThe along-isobath temperature and salinity gradients compensate for each other so that the mean, depth-averaged, along-isobath density gradient is approximately zero. This suggests that there may be a feedback between the along-isobath density gradient and the onshore salt and heat fluxes that maintains the density gradient near zero.
机译：通过测试以下假设来研究中大西洋中部大陆架上的平均热量和盐分平衡：热或淡水的表面通量由沿均值，沿均值的平均深度，沿等值线流动所产生的沿等值通量平衡。 ，平均深度，沿等温线温度或盐度梯度。这种假设的平衡在拉格朗日框架中等同于一列水，例如由于表面加热导致的变暖，因为它是通过等流量沿等压线向南平流向南移动的。平均深度平均温度沿等压线从北向南以一定速率增加中层温度为2℃（1000 km）〜（-1），与50年NCEP重新分析的假设平衡和平均表面热通量估算值一致。然而，高分辨率的20年客观分析的海-气通量（OAFlux）重新分析得出的平均表面热通量估计值太小，无法平衡沿等温线的热通量发散，这意味着跨架热通量会聚。目前尚不清楚哪种表面热通量估算值（NCEP或OAFlux）更准确。平均层架环流导致的层架热通量收敛太小而无法平衡沿等温槽的热通量发散.rn平均深度平均盐度沿北向南沿着等压线以1（psu）的速率增加（1000 km）〜（-1）在架子上。平均降水和蒸发率几乎达到平衡，因此净淡水通量太小一个数量级以上，无法解释盐度沿等值浴的增加。由平均跨架循环引起的跨架盐通量发散具有错误的符号，无法平衡沿等温浴盐通量的发散。这些结果表明，随时间变化的电流和盐度变化必然会导致陆上“涡流”盐通量。沿等温线温度和盐度梯度会相互补偿，因此平均，深度平均，沿等温线密度梯度大约为零。这表明沿等温线密度梯度与陆上盐和热通量之间可能存在反馈，使密度梯度保持接近零。

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  • 来源
    《Journal of Physical Oceanography》 |2010年第5期|934-948|共15页
  • 作者

    Steven J.Lentz;

  • 作者单位

    Woods Hole Oceanographic Institution, MS 21, Woods Hole, MA 02543;

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  • 正文语种 eng
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