Latitudinal dependence of diapycnal diffusivity in the thermocline observed using a microstructure profiler
Latitudinal dependence of diapycnal diffusivity in the thermocline observed using a microstructure profiler
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DOI：
10.1029/2007gl032323
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发表时间：
2007-12
影响因子：
5.2
通讯作者：
T. Hibiya;M. Nagasawa;Y. Niwa
中科院分区：
文献类型：
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作者：
T. Hibiya;M. Nagasawa;Y. Niwa
自由落体微结构剖面仪“TurboMAP-D”在太平洋内部收集了53个速度微结构剖面。利用1000 ~ 1600 m深度的资料，推断了主温跃层的底辟扩散系数。我们发现20°-30 ° N的径向扩散率与半日内潮的局部可用能量密度的对数大致成正比，在伊豆-小笠原海脊附近达到10−4 m2 s−1以上。相比之下，在20°N赤道方向和30°N极地方向，无论当地可获得的半日内潮能量的多少，经向扩散率都保持在10 - 5 m2 s-1。观察到的混合热点比基于精细尺度参数化的预测低2-3倍，尽管需要进一步的微观结构测量来更好地量化它们。本研究证实了全球环流模式中必须考虑到的纬向依赖的diapycnal扩散率的存在。
The un‐tethered free‐fall microstructure profiler “TurboMAP‐D” collected 53 velocity microstructure profiles in the interior Pacific Ocean. The data between ∼1000 m and ∼1600 m depth was used to infer diapycnal diffusivity in the main thermocline. We found diapycnal diffusivity at 20°–30°N was roughly proportional to the logarithm of locally available energy density of the semidiurnal internal tide and reached more than 10−4 m2 s−1 near the Izu‐Ogasawara Ridge. In contrast, diapycnal diffusivity was found to remain at ∼10−5 m2 s−1 equatorward of 20°N and poleward of 30°N, irrespective of the amount of locally available semidiurnal internal tide energy. The observed mixing hotspots were a factor of 2–3 less intense than predicted based on fine‐scale parameterizations, although further microstructure measurements are needed to better quantify them. The present study has confirmed the existence of a latitudinal dependence of diapycnal diffusivity which must be taken into account in global circulation models.