The interaction between atmospheres and oceans plays an important role in the global climate. In a field experiment of atmospheric flows over the Gulf Stream, when the wind blew from the cold water to the warm water, we observed a near-surface jet over the warm water. We then conducted direct numerical simulations and large-eddy simulations of atmospheric turbulence in the vicinity of the front and captured the near-surface jet in simulations for the first time. Analyses of the data obtained from the high-resolution three-dimensional simulations revealed the dominant generation mechanisms of the near-surface jet, which are the strong vertical mixing by the enhanced streamwise rolls and the mean downward motion. Around the near-surface jet, the magnitude of the negatively valued Richardson number significantly increases, indicating the dominance of buoyancy effects in the flow dynamics there. The development of the near-surface jet suggests that the Monin-Obukhov similarity theory (MOST) needs to be modified in representing marine atmospheric boundary layers over sea surface temperature fronts.
Bibliographical noteFunding Information:
This research is supported by the Office of Naval Research as part of the MURI Coupled Air‐Sea Process and Electromagnetic ducting Research (CASPER) project managed by Dr. Daniel Eleuterio and Dr. Steven Russell, with Grant N00014‐16‐1‐3205 to Lian Shen and Grant N0001420WX01066 to Qing Wang. Lian Shen also gratefully acknowledges the support by Grant N00014‐20‐1‐2749 managed by Dr. Scott Harper. We would like to thank the anonymous reviewers for the helpful comments and suggestions.
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- atmospheric turbulence
- direct numerical simulation
- large-eddy simulation
- near-surface jet
- oceanic front