The imprint of marine atmospheric boundary layer (MABL) dynamical structures on sea surface roughness, as seen from Sentinel-1 Synthetic Aperture Radar (SAR) acquisitions, is investigated. We focus on February 13th, 2020, a case study of the EUREC4A (Elucidating the role of clouds-circulation coupling in climate) field campaign. For suppressed conditions, convective rolls imprint on sea surface roughness is confirmed through the intercomparison with MABL turbulent organization deduced from airborne measurements. A discretization of the SAR wide swath into 25 x 25 km2 tiles then allows us to capture the spatial variability of the turbulence organization varying from rolls to cells. Secondly, we objectively detect cold pools within the SAR image and combine them with geostationary brightness temperature. The geometrical or physically-based metrics of cold pools are correlated to cloud properties. This provides a promising methodology to analyze the dynamics of convective systems as seen from below and above.

Key Points

Atmospheric coherent structures, rolls and cold pools are systematically detected and analyzed in a high-resolution SAR wide swath image

Properties of rolls from SAR measurements are comparable with the circulation organization deduced from airborne data

A diversity of cold pool geometrical and dynamical features is related to cloud life cycle provided by satellite brightness temperature

Plain Language Summary

We propose an innovative approach to investigate the marine atmospheric boundary layer dynamics by combining spaceborne Synthetic Aperture Radar (SAR) images, brightness temperature from the Geostationary Operational Environmental Satellite (GOES) and in situ turbulence airborne measurements. Focusing on February 13th, 2020, two types of atmospheric processes are investigated: trade wind boundary layer organizations and cold pools. The signature of coherent structures on sea surface roughness, especially convective rolls, is validated with respect to the turbulence airborne measurements. The cold pools are detected within the SAR image using an identification technique based on the filtering of backscatter signal increments. Cold pool characteristics such as their size or the gust front intensity can then be directly derived from the SAR image. The GOES images provide cloud field properties every 10 min. Exploring backward cloud evolution with respect to the SAR image timing appears able to catch the life cycle of cold pools and convective clouds from which they originate. The application of this approach could pave the way to access the dynamics of convective systems as seen from below and above, allowing to go one step further in the quantitative use of SAR images to investigate boundary layer processes.