Air-Sea Fluxes with a Focus on Heat and Momentum
OOPC Leads: Meghan Cronin and Tong Lee
Aim
Turbulent and radiative exchanges of heat between the ocean and atmosphere (hereafter heat fluxes), ocean surface wind stress, and state variables used to estimate them, are Essential Ocean Variables (EOVs) and Essential Climate Variables (ECVs) influencing weather and climate.
Our aim is to develop an observational strategy for producing 3-hourly, 25-km (and an aspirational goal of hourly at 10-km) air-sea heat flux and wind stress fields over the global, ice-free ocean with a breakthrough 1-day random uncertainty of 15 W m-2 and a bias of less than 5 W m-2.
This work will be carried out as part of the Observing Air-Sea Interactions Strategy (OASIS), which is a multi-disciplinary global strategy under development to:
- monitor and predict the ocean’s influence on global weather and climate on timescales of days-seas-decades
- monitor and predict marine weather in the ocean and atmosphere
- track ocean update of carbon dioxide and oceanic deoxygenation and denitrification
- study how biology, biodiversity, and the surface ecosystems relate to changes in surface concentrations and fluxes of CO2, DMS, and N2O.
Motivation
Advancing our ability to predict long-term weather and climate shifts requires an improved understanding of how the ocean influences weather and climate and better quantification of air-sea exchanges of heat. Oceanic heat loss due to evaporation is associated with moisture fluxes that are an important source of water for life on Earth. Understanding and quantifying the exchange of heat and momentum between the ocean and atmosphere is therefore critically important for management of natural resources, and supply chains for food, water, and energy. A more complete picture of seasonal and interannual weather variation and better climate forecasting will allow us to anticipate and respond appropriately, protecting habitats and ecosystems and reducing risks to vulnerable people around the world.
An observing system that is able to accurately map the exchanges of heat between the ocean and atmosphere would also be able to accurately measure the wind stress that drives ocean circulation and could be leveraged to track the ocean uptake of anthropogenic carbon. Tracking the ocean’s long-term uptake of human-produced carbon dioxide is critical to understanding both the pace of ocean acidification and how fast atmospheric carbon dioxide levels will rise in the future. This strategy is thus vitally important for understanding and quantifying the Earth’s energy, water, and carbon cycles.
A 10-year Roadmap
A community white paper (Cronin et al. 2019), written by 27 worldwide experts for OceanObs’19, lays out a 10-year roadmap for making air-sea flux maps with breakthrough accuracy. The plan calls for (1) optimization of satellite-based observations for boundary layer measurements of air temperature, humidity, sea surface temperature, and ocean wind stress; and (2) creating a complementary global in situ flux array. The plan also recommends some near-term and medium-term activities that would support these two major recommendations.
At OceanObs’19, lead authors of air-sea flux Community White Papers agreed to collaborate on the development of the multi-disciplinary Observing Air-Sea Interactions Stratgy (OASIS). This strategy is being led by OOPC panel member Meghan Cronin, and the OOPC air-sea flux activity will be an integral part of this activity.
Activities
A proposal for the OASIS project was submitted to SCOR to develop the strategy and accepted (SCOR Working Group #162) in 2021. In that same year, OASIS was officially adopted as a Program within the UN Decade of Ocean Science for Sustainable Development.
You can find more information on OASIS Program here