Modeling Arabian Sea Boundary Layer and Upper Ocean Coupling
Abstract
The annual cycle of sea surface temperature (SST) in the Arabian Sea (AS) has two maxima. Intense warming in boreal spring generates the strongest SST maximum, which provides moist static energy fluxes at the southwesterly monsoon onset. As the southwesterly monsoons continue, the AS SST cools almost as fast as it had warmed. The stratification of the upper ocean affects the strength and depth of the warm water in the AS, and it affects the subsequent response of the temperature to strong surface winds during the monsoon.This project models the processes in the atmosphere that generate surface stress, heat, and moisture fluxes, and the turbulent responses in the ocean mixed layer and in the marine atmospheric boundary layer at the time of SW monsoon onset when SST and winds are high. The entrainment of heat, moisture, density, and momentum at the top of the atmospheric mixed layer and at the base of the ocean mixed layer are of particular interest because they control the fluxes through the air-sea interface.The project will help to determine 1) what local processes are responsible for the cooling SST in the warm pool after monsoon onset, and whether these processes can explain the warm SST persistence bias found in climate models. The project will 2) quantify the buoyancy, energy, and moisture fluxes between the cloud and sub cloud layer at the MABL top, and describe the roles of turbulent subcloud mixed layer entrainment, andcoherent cloud circulations such as downdrafts, in setting these fluxes.Large eddy simulations (LESs) embedded within a coupled regional model resolve a variety of energy containing processes, such as clouds and evaporative cold pools in the atmosphere, and inertial adjustment and shear instabilities in the ocean. The LES resolves generation of turbulence in the atmosphere and ocean mixed layers by these processes, and the influence of the turbulence on vertical entrainment. These explicitly resolved turbulent fluxes in the LES will be compared with parameterized cloud and turbulent scale fluxes in the regional model. The response of the ocean modeled by the 1D K-profile parameterization with forcing from the atmospheric LES will be compared to the ocean LES. Metrics of turbulentkinetic energy (TKE), its dissipation rate, and processes which generate it will be computed from turbulence-resolving velocity measurements by Doppler lidar in the atmosphere, and profiler and acoustics measurements in the ocean mixed layer.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 24, 2023
- Source ID
- N000142312253
Entities
People
- Simon P. de Szoeke
Organizations
- Office of Naval Research
- Oregon State University
- United States Navy