SHEAR AND STRAIN IN SANTA-MONICA BASIN
SHEAR AND STRAIN IN SANTA-MONICA BASIN
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DOI：
10.1029/91jc01385
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发表时间：
1991-09-15
影响因子：
3.6
通讯作者：
KUNZE, E
中科院分区：
文献类型：
--
作者：
GREGG, MC;KUNZE, E
Ledwell和沃森（1991年）通过向圣莫尼卡盆地790米深处注入SF6云团并观察其垂直扩散，估计750米至850米之间的平均穿透扩散率为K ρ = 2.5 x 10（-5）m2 s-1。这一扩散率高于从开阔洋温跃层典型内波水平的微结构测量中推断出的扩散率（Gregg和Sanford，1988年）。为了检查盆地中的剪切和应变，我们投下了一次性电流剖面仪（XCP），并根据电导率、温度和深度（CTD）模型计算了应变。剪切和应变高于GM 76模型谱（加勒特和Munk，1975年;凯恩斯和威廉姆斯，1976年），与已发表的参数化比较表明，剪切方差足以解释Ledwell和沃森报告的高扩散率。因此，在圣莫尼卡盆地的涡流扩散率是不符合较低的值估计从微结构测量在公海，但由于内部波场升高。然而，光谱形状不同于典型的公海光谱。
By injecting a cloud of SF6 into Santa Monica Basin at a depth of 790 m and observing its vertical spread, Ledwell and Watson (1991) estimate the average diapycnal diffusivity between 750 and 850 m as K-rho = 2.5 x 10(-5) m2 s-1. This diffusivity is higher than inferred from microstructure measurements in the open-ocean thermocline for typical internal wave levels (Gregg and Sanford, 1988). To examine shear and strain in the basin, we dropped expendable current profilers (XCPs) and calculated strain from conductivity, temperature, and depth (CTD) casts. Shear and strain are above the GM76 model spectrum (Garrett and Munk, 1975; Cairns and Williams, 1976), and comparisons with published parameterizations indicate more than enough shear variance to account for the high diffusivity reported by Ledwell and Watson. Thus, the eddy diffusivity in Santa Monica Basin is not at odds with lower values estimated from microstructure measurements in the open ocean, but is due to an elevated internal wave field. The spectral shapes, however, differ from typical open-ocean spectra.