rabernat commented 2 years ago

Impact of resolution on the atmosphere–ocean coupling along the Gulf Stream in global high resolution models

dhruvbalwada commented 2 years ago

Local Air-Sea Interactions at Ocean Mesoscale and Submesoscale in a Western Boundary Current

paigem commented 2 years ago

I plan to read and briefly present these 2 papers at our next meeting on Monday, April 11 (US time).

paigem commented 2 years ago

Impact of resolution on the atmosphere-ocean coupling along the Gulf Stream in global high resolution models

By E.E. Tsartsali et al. Climate Dynamics (2022)

They determine how horizontal resolution affects air-sea interaction over the Gulf Stream, specifically the mechanisms of vertical mixing (VMM) and pressure adjustment (PAM)
They use data from 6 models (from PRIMAVERA funded) in HighResMIP, where they classify the models into 4 categories:
- eddy-parameterized (1 degree ocean, atm 100-250km)
- eddy permitting (0.25-0.4 degree ocean, 50-100km atm)
- eddy permitting with increased atmospheric resolution (0.25-0.4 degree ocean, 25-50km atm)
- eddy resolving - only 1 model (1/12 degree ocean, 50km atm)
They also compare to reanalyses and observations
They find that eddy-permitting with comparable atmospheric resolution is required to correctly capture the air-sea interaction in the Gulf Stream

They only look at wintertime (DJF) air-sea interaction, since it is strongest then (due to increased temperature difference between ocean and atm)
They use monthly values over 100 years of data
They interpolate ocean variables to atmospheric grid first (since the atmosphere can't resolve the finer scales anyway)
They compute downwind and crosswind SST gradient as the projection (and its perpendicular) on the wind stress vector. They also compute the wind stress divergence and curl, and the Laplacian of SLP (sea level pressure) and SST.
The detrend the data and apply a high-pass filter by subtracting off a boxcar smoothed (18 degree lon x 6 degree lat) version of the fields to isolate the mesoscales
Finally, they compute the linear relationship between fields via least squares regression, and also compute the coupling coefficient.

The claim is that the plots look more like the observations shown in Figure 1 as you move from right to left in any given row in this plot.

Local Air-Sea Interactions at Ocean Mesoscale and Submesoscale in a Western Boundary Current

By Strobach et al. GRL (2022)

They study small-scale air-sea interaction in the Gulf Stream, specifically how wind and SST anomalies interact
They use a high resolution (3km ocean, 6km atm) over 3 (summer) months
They show that intermittent wind events fuel latent heat bursts over warm SST anomalies that are associated with the strength of the submesoscale SST fronts (they call this process secondary circulation)
They go into great detail about what happens when an air mass passes over an SST front, both in the horizontal and vertical dimensions
The stress the importance of resolving submesoscale, as these small spatial scales can affect the atmosphere at such short time scales (e.g. a few hours) that the atmosphere doesn't have time to adjust, thus indicating that the ocean is driving the atmosphere. It's in these scenarios when the secondary circulation is created.

Note: what I've written here is a bit more in depth than what is included in Literature.md