Recent studies highlight the importance of small-scale coherent structures associated with atmospheric convection and (sub-)mesoscale ocean dynamics on atmosphere-ocean feedbacks in key regions of the climate system. In state-of-the-art coupled climate models, such small-scale atmosphere-ocean feedbacks are either ignored or rely on parameterizations, which may lead to model biases and energetic inconsistencies.
Here, we propose to investigate these small-scale coupling mechanisms using coupled simulations on a global scale, based on resolutions allowing us, for the first time, to directly simulate the underlying key processes. More specifically, we will focus on the following topics:
- With the help of storm-resolving coupled simulations and data from a large-scale field experiment, we will investigate the interaction of shallow atmospheric convection and near-surface processes in the ocean. A special focus here will be on the dynamics of thin (meter-scale) "diurnal warm layers" and "rain layers" at the ocean surface, their role in mediating air-sea fluxes, and their feedback with atmospheric convection.
- We will study the effect of parameterized submesoscale dynamics like baroclinic instability and symmetric instability on air-sea exchanges in key regions of oceanic and atmospheric convection.
- We aim to clarify the effect of resolved mesoscale eddies on air-sea coupling, develop a new stochastic parameterization that represents such effects in surface fluxes of heat and momentum, and investigate the global and regional impact of the parameterization in coupled atmosphere-ocean simulations that cannot use high enough resolution to represent those processes explicitly.
Rackow, T., & Juricke, S (2019). Flow‐dependent stochastic coupling for climate models with high ocean‐to‐atmosphere resolution ratio. Q. J. Roy. Meteor. Soc., 1-17, https://doi.org/10.1002/qj.3674.