Understanding Processes Controlling Near-Surface Salinity in the Tropical Ocean using Multiscale Coupled Modeling and Analysis

Objectives: Our interests are in understanding the complex processes that control the distribution of salinity in the ocean boundary layer (OBL) over a wide range of spatial and temporal scales, including both oceanic and atmospheric processes. Our investigation would utilize existing data sets taken in the eastern Pacific Ocean during the SPURS-2 field campaign combined with simulations and numerical modeling. The project seeks to answer questions regarding the relative importance precipitation, evaporation, diurnal variability, temperature stratification and barrier layers play on the OBL structure and upper ocean mixing processes, and how this variability affects air-sea exchanges of heat, freshwater, and momentum and resulting atmospheric convection and precipitation. The results of this investigation will then be used to answer the following questions: What measurements would be required to shed light on these processes at the frontal region of the warm/fresh pool? What measurements would be needed to improve the way we parameterize these processes in coarser-resolution models?
Relevance 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 distribution of salinity in the ocean boundary layer over a wide range of spatial and temporal scales, including both oceanic and atmospheric processes 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, this research is directly related to the goal of gaining a process-level understanding of how the atmosphere-ocean system interacts, a major goal of the CVP Program.
Summary of Work: Our proposed work will include: (1) analysis of the comprehensive oceanic and atmospheric data sets from the SPURS-2 field campaign in light of our research questions and comparisons of these data with our model simulations; (2) simulations using cloud-resolving large eddy simulation (LES) models coupled to a mixed layer ocean model to examine how convective precipitation produces stratified, fresh water regions and the evolution of these fresh regions over time; (3) evaluation of wind- and buoyancy-forced OBL mixing processes using high-resolution ocean LES and one-dimensional turbulence models initialized with measured and modeled vertical structure and surface fluxes, and (4) recommendations based on these results for important measurements and associated time and space scales for the TPOS warm/fresh pool study to provide further insight into the oceanic and atmospheric processes occurring in that region.