Observations of near-inertial energy in Lake Superior
Observations of near-inertial energy in Lake Superior
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DOI：
10.4319/lo.2013.58.2.0715
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发表时间：
2013-03-01
影响因子：
4.5
通讯作者：
Austin, Jay
中科院分区：
文献类型：
--
作者：
Austin, Jay
2008年至2011年在上级湖收集的直接测量速度数据显示，该湖开放沃茨的水流主要由近惯性能量控制。近惯性信号几乎完全由顺时针旋转组成，垂直结构由第一斜压模态主导，其中温跃层上方和下方的沃茨彼此相差约180度。振荡的强度与分层的强度密切相关;在一年中水柱混合良好的时期（通常是晚秋和晚春），近惯性信号非常弱;当分层存在时，近惯性振荡可能发生。结合速度振幅与温跃层位移的估计，可以估计近惯性场的主导方向和水平波长，表明水平波长约为50-100公里，波浪的方向在整个季节逆时针转向，周期约为1个月。后向散射观测表明，惯性振荡可能是造成海底沉积物重新悬浮的原因，这可能会产生重大的生态后果。
Directly measured velocity data collected in Lake Superior between 2008 and 2011 show that currents in the open waters of the lake are dominated by near-inertial energy. The near-inertial signal is composed almost entirely of clockwise rotation, with vertical structure dominated by the first baroclinic mode, where waters above and below the thermocline are roughly 180 degrees out of phase with each other. The strength of the oscillations is strongly related to the strength of the stratification; in periods of the year when the water column is well-mixed (typically late autumn and late spring) the near-inertial signal is very weak; when stratification exists, near-inertial oscillations can occur. Combining the velocity amplitudes with an estimate of the thermocline displacement allows estimation of the dominant direction and horizontal wavelength of the near-inertial field, showing that horizontal wavelengths are on the order of 50-100 km, and the direction of the waves veers counter-clockwise over the course of the season with a period of similar to 1 month. Observations of backscatter suggest that inertial oscillations may be responsible for re-suspension of bottom sediments, which could have significant ecological consequences.