Thermodynamic and Radiative Structure of Stratocumulus-Topped Boundary Layers*

• Published in: Journal of the Atmospheric Sciences
• Main Authors: Ghate, Virendra P., Miller, Mark A., Albrecht, Bruce A., Fairall, Christopher W.
• Language: unknown
• Published: 2021
• Subjects: 54 ENVIRONMENTAL SCIENCES; Pacific; North Atlantic
• Online Access: http://www.osti.gov/servlets/purl/1396177; https://www.osti.gov/biblio/1396177; https://doi.org/10.1175/JAS-D-13-0313.1

Stratocumulus Topped Boundary Layers (STBL) observed in three different regions with distinctive environments are described in the context of their thermodynamic and radiative properties. Here, the primary data set consisted of 131 soundings from the South East Pacific (SEP), 90 soundings from the island of Graciosa (GRW) in the North Atlantic and 83 soundings from the US Southern Great Plains (SGP). A new technique that preserves the depths of the sub-layers within a STBL is proposed for averaging the profiles of thermodynamic and radiative variables. The STBL was deepest over SEP and had the strongest radiative cooling rates near cloud top among the three locations. Although the radiative cooling rates were comparable over GRW and SGP, the STBL was deeper over GRW compared to that over SGP. On average the STBL inversion was strongest over SEP (11.7 k and -5.43 g kg -1 ) and weakest over the SGP (6.89 k and -0.41 g kg -1 ). Significantly larger liquid water path, integrated water vapor, and variability in these two properties was found over GRW and evidence presented suggests that conditions at cloud top may play a lesser role in determining the resident cloud structure over GRW than over SEP. A modal analysis revealed ~26% of the STBL to be well-mixed, ~20% of STBL to be stable and ~30% STBL having a stable layer in-between a surface mixed layer and the cloud layer. Over all the three locations, the STBL was shallowest in well-mixed mode and deepest in the stable mode.