Scale Dependence of Midlatitude Air-Sea Interaction
Scale Dependence of Midlatitude Air-Sea Interaction
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DOI：
10.1175/jcli-d-17-0159.1
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发表时间：
2017-10-01
影响因子：
4.9
通讯作者：
Tomas, Robert A.
中科院分区：
文献类型：
--
作者：
Bishop, Stuart P.;Small, R. Justin;Tomas, Robert A.
传统上认为，中纬度海表温度（SST）变率主要是由与天气变率相关的海气表面热通量（SHFs）的变化驱动的。结果表明，在气候海温梯度和超强海温向大气损失最大的地区，海温和超强海温在月和更长时间尺度上的变率是由内部海洋过程驱动的，这里称为“海洋天气”。“这是在一个包括大气和海洋随机强迫的耦合海气相互作用的能量平衡模型的背景下显示的。SST和SHF之间滞后相关的功能形式使我们能够区分由大气和海洋天气驱动的变率。观测结果表明，海温-海温和海温趋势-海温相关的滞后函数关系反映了西边界流和南极环极流中海洋驱动的海温变化。通过对海温的时空平滑处理，减弱了涡旋搅拌产生的海温特征异常，结果表明，海洋对海温变率的影响随时间尺度增大而增大，随空间尺度增大而减小。wbc和ACC的海温变率从海洋驱动向大气驱动转变的尺度发生在小于500 km的尺度。这个过渡尺度强调了在耦合气候模式中解析中尺度涡旋以充分模拟海气相互作用变率的必要性。远离强海温锋面，滞后的函数关系表明了大气驱动海温变率的传统范式。
It has traditionally been thought that midlatitude sea surface temperature (SST) variability is predominantly driven by variations in air-sea surface heat fluxes (SHFs) associated with synoptic weather variability. Here it is shown that in regions marked by the highest climatological SST gradients and SHF loss to the atmosphere, the variability in SST and SHF at monthly and longer time scales is driven by internal ocean processes, termed here "oceanic weather.'' This is shown within the context of an energy balance model of coupled air-sea interaction that includes both stochastic forcing for the atmosphere and ocean. The functional form of the lagged correlation between SST and SHF allows us to discriminate between variability that is driven by atmospheric versus oceanic weather. Observations show that the lagged functional relationship of SST-SHF and SST tendency-SHF correlation is indicative of ocean-driven SST variability in the western boundary currents (WBCs) and the Antarctic Circumpolar Current (ACC). By applying spatial and temporal smoothing, thereby dampening the signature SST anomalies generated by eddy stirring, it is shown that the oceanic influence on SST variability increases with time scale but decreases with increasing spatial scale. The scale at which SST variability in the WBCs and the ACC transitions from ocean to atmosphere driven occurs at scales less than 500 km. This transition scale highlights the need to resolve mesoscale eddies in coupled climate models to adequately simulate the variability of air-sea interaction. Away from strong SST fronts the lagged functional relationships are indicative of the traditional paradigm of atmospherically driven SST variability.