Thermohaline variability in the upper ocean
Thermohaline variability in the upper ocean
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DOI：
10.1029/2000jc900057
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发表时间：
2000-07-15
影响因子：
3.6
通讯作者：
Rudnick, DL
中科院分区：
文献类型：
--
作者：
Ferrari, R;Rudnick, DL
这项探索性研究的主要目标是确定温度-盐度关系如何随海洋水平长度尺度和深度而变化。温度和盐度的测量范围从4米到1000公里，拖着一个SeaSoar沿着等压线和isopycnals在副热带环流的北部。太平洋，1997年冬天。小波变换技术被用来计算水平密度比和温盐变率作为尺度和位置的函数。沿混合层等压线的沿着测量表明，在所有观测尺度上，水平密度比均为1;也就是说，水平温度梯度和盐度梯度对密度的影响趋于相互抵消。小尺度的温盐变率是间歇性的，并围绕大尺度的温盐异常聚集。在混合层底部以下，温度的水平梯度仅部分地与盐度相反，密度比接近2。在温跃层中，温盐变率沿着等压线的分布是均匀的，但沿着等密度线的分布是间歇性的，并在不同尺度上共存。在混合层中普遍存在的密度补偿变率沿沿着较深的等密度线减小。水平温度和盐度梯度的补偿支持最近的理论观点，即冬季混合层中的混合取决于水平密度梯度。
The main goal of this exploratory study is to determine how the temperature-salinity relationship changes with horizontal length scale and depth in the ocean. Temperature and salinity were measured on a range of scales from 4 m to 1000 km, towing a SeaSoar along isobars and isopycnals in the subtropical gyre of the North. Pacific, during the winter of 1997. The wavelet transform technique is used to compute the horizontal density ratio and thermohaline variability as a function of scale and location. Measurements along an isobar in the mixed layer show that the horizontal density ratio is 1 at all scales observed; that is, horizontal temperature and salinity gradients tend to cancel each other in their effect on density. Thermohaline variability at small scales is intermittent and clusters around large-scale thermohaline anomalies. Below the base of the mixed layer, horizontal gradients of temperature are only partially opposed by salinity, and the density ratio is close to 2. In the thermocline the distribution of thermohaline variability is uniform along isobars but intermittent and colocated at different scales along isopycnals. Density-compensated variability, ubiquitous in the mixed layer, is reduced along deeper isopycnals. Compensation of horizontal temperature and salinity gradients supports recent theoretical ideas that mixing in the winter mixed layer depends on horizontal density gradients.