The Behavior of Atmospheric Boundary Layer near SST Fronts near the Gulf Stream

Hanyuan Liu1, James B Edson2 and Carol Anne Clayson1, (1)Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, MA, United States, (2)Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Challenges remain in understanding the behavior of the ocean-atmosphere boundary layer near an SST front due to the highly turbulent variability in such environment. With better measurements and parameterization, however, it is worthwhile to re-analyze old data set and compare them to recent collected data to better investigate such topic. Observational data from the CLIvar Mode Water Dynamic Experiment (CLIMODE,2006) and the Processes Driving Exchange at Cape Hatteras (PEACH,2018) experiment cruise were studied to examine the impact of a sharp SST front on the boundary layer formation near the Gulf Stream. Multiple rawinsondes launches throughout both cruises provided sounding profiles that recorded the potential inversions in the ABL.On-board ship measurements of winds, temperature, and humidity were processed with updated COARE4.0 to provide better parameteriztion of the heat flux, while direct covariance measurements of fluxes were also made. SST fronts were identified with both ship measurements and satellite data. Results showed that whether the wind was blowing from cold side to warm side or the oppsite, had a significant impact on the boundary layer fomation. In cases where winds were blowing from cold side to warm side fluxes data showed a more convective boundary layer while in cases where the wind was blowing from warm to cold MABL tended to be more stable. Wind velocity component perpendicular to the front was also found to be a strong factor affecting the inversion height.