Coupling of the Tropical Air-sea Boundary Layers: Resolving Key Processes Using Observations and Multi-scale Coupled Modeling and Analysis

Our interests are in understanding the key features needed to more accurately represent both atmospheric and oceanic boundary layer processes, which are crucial for robust prediction of tropical atmosphere-ocean interactions. To do this we need to understand the structure of the boundary layers and develop a plan for measurement that fits both the scale of active processes and the needs of parameterization development. Our investigation would utilize existing tropical data sets and numerical modeling. The goal of this proposal is to use the sensitivity of coupled models to changes in boundary layer resolution and parameterizations as a tool to develop a field measurement strategy. We hypothesize that determining the correct resolution and parameterization for representing a process in a model provides a first estimate of resolution needs of measurements. With model results for guidance, we plan to provide metrics for various measurement platforms that will hone in on both the correct resolution and type of instrument array. Our experiments will also help in developing the overall observation strategy.
Relevance and Broader Impacts of Proposed Research: The overall objective of the “Air-Sea Interaction at the eastern edge of the Warm Pool” is to better understand the impact of air-sea interaction and the upper ocean salinity stratification in maintaining the warm SSTs at the eastern edge of the west Pacific warm pool. Our interests are in understanding the complex processes that control the coupled atmosphere-ocean boundary layers in this region, using observations and a hierarchy of modeling approaches, directly in line with CVP Program priorities. The results of this research are aimed
specifically at providing information on the atmospheric and oceanic observations needed and the time and space scales required to adequately capture the relevant processes of interest in maintaining the temperature and salinity stratification in the eastern edge of the west Pacific warm pool region. Further, with our focus on the impacts of coupling on convection and precipitation in this region, the research is directly related to improving understanding and representation of the structure of precipitation in this key region for global precipitation predictability, supporting NOAA’s Precipitation Prediction Grand Challenge.
Our proposed work will include analysis from observations and uncoupled and coupled models of: (1) impacts of flux parameterizations on the upper ocean and the coupled system; (2) evaluation of the effects of including wave data into upper ocean processes, fluxes, and coupled feedbacks; (3) simulations using cloud-resolving large-eddy simulation (LES) models coupled to a mixed layer ocean model to evaluate the impact of vertical ocean model resolution on key processes; (4) simulations using coupled WRF-ROMS models to evaluate the impact of vertical atmospheric model resolution on key convective processes (e.g. cold pools); (5) usefulness of parameterizations of diurnal SST warming and changes in upper ocean salinity due to precipitation in reproducing the coupled system, and (6) recommendations of metrics for various measurement platforms that will hone in on both the correct resolution and type of instrument array needed to accurately capture processes relevant for air-sea interaction in the tropical Pacific.