Estimates of dissipation of turbulent kinetic energy were made from temperature gradient microstructure profiles collected in five small, dimictic temperate lakes under a range of atmospheric forcing. Buoyancy frequencies exceeded 0.02 s-1 at the seasonal thermoclines of these dimictic kettle lakes. Turbulence was dampened by strong stratification as average dissipation rates were low (10-9 m2s -3) below the surface mixing layer. Average dissipation in excess of 10-7 m2s-3 was only found in the upper meter following an episodic thunderstorm with wind speeds of 5 m s-1. Persistent epilimnetic stratification formed on most summer days. There was no evidence of deepening of the surface mixing layer in response typical afternoon winds of 2-3 m s-1. At a diel timescale, deeper mixing resulted from overnight heat loss (buoyancy flux ∼1x10-7m2s-3) than from afternoon wind stress. The passage of episodic storm fronts resulted in deeper epilimnetic mixing with moderate dissipation. The strong stratification and lack of mixing has implications for pelagic plankton with limited or no mobility. In particular, strong stratification inhibited the resuspension of infective fungal spores settled into the lake sediments through mid-summer. Outbreaks of infection in populations of zooplankton occur synchronously across lakes following late summer cold fronts. The enhanced mixing resulting from storm fronts could resuspend and transport infective spores.
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机译：湍流动能消散的估算是根据在一定的大气强迫作用下从五个小型的，模拟的温带湖泊中收集的温度梯度微观结构剖面得出的。在这些小型壶湖的季节性温床上，浮力频率超过0.02 s-1。由于在表面混合层以下的平均耗散率较低（10-9 m2s -3），因此强烈的分层减弱了湍流。仅在风速为5 m s-1的阵雨和雷暴过后的高层仪表中，才发现平均耗散超过10-7 m2s-3。在大多数夏季，会形成持久的外缘分层。没有证据表明典型的下午风为2-3 m s-1时，表面混合层会加深。在diel时间尺度上，过夜热量损失（浮力通量约为1x10-7m2s-3）比下午的风压引起的混合更深。阵发性风暴锋的通过导致更深的表生混合和适度耗散。强烈的分层和缺乏混合对上浮游生物的流动性有限或没有影响。尤其是，强烈的分层抑制了盛夏中期沉积在湖泊沉积物中的感染性真菌孢子的重悬。夏末冷锋之后，跨湖泊的浮游动物种群中的感染爆发同步发生。风暴前锋导致的混合增强可能会重悬和传播感染性孢子。
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