Understanding Coupled Ocean-Atmosphere Processes at the Eastern Edge of the Warm Pool in Support of TPOS 2020

The eastern edge of the warm pool marks the boundary between the western Pacific warm pool, where large-scale winds converge to form deep convection, and the equatorial cold tongue water to the east, where trade winds prevail. During El Niño, the eastern edge of the warm pool migrates eastward, shifting the location of the deep convection with it. The purpose of this study is to use a high resolution coupled ocean-atmosphere model to 1) understand the ocean-atmosphere interactions that play a role in both affecting the sharpness of the front and causing it to migrate eastward during onset of the El Niño; and 2) investigate the observational needs that would help model development and improve prediction of El Niño onset.
In this study, we use the high-resolution Unified Wave Interface-Coupled Model (UWIN-CM) to investigate the coupled ocean-atmosphere and upper ocean processes at the edge of the warm/fresh pool. UWIN-CM is a fully coupled ocean-atmosphere model with explicit coupling physics at the ocean-atmosphere interface, which is uniquely suited for studying the air-sea interaction processes. It consists the Hybrid Coordinate Ocean Model (HYCOM) and the Weather Research and Forecasting (WRF) model. It has been fully tested for real time prediction over the Gulf of Mexico since 2012. It is currently a primary modeling tool for studying the coupled ocean-atmosphere processes in the MJO over the Maritime Continent. HYCOM and WRF will be configured over the western Pacific domain with 41 layers and 1/12 degrees for the ocean and 45 vertical levels and 4 km grid spacing for the atmosphere. Its cloud-permitting capability at 4 km is critical for this study
This proposed research is in response to the CVP solicitation — Pre-Field Modeling Studies in Support of TPOS Process Studies, a Component of TPOS 2020, which “aim to determine the relevant processes that are important for the ENSO development and their spatial and temporal scales need to be resolved in models and observations”. Results from this project would provide a better understanding and quantitative assessment on possible sources of the ENSO prediction barrier problem in numerical models. This would guide the strategy of TPOS 2020 observations in general, and help fulfill NOAA’s long-term climate goal of improved scientific understanding of the changing climate system and its impacts, and address challenges in weather and climate extremes.