Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-59
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Feb 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
A satellite and reanalysis view of cloud organization, thermodynamic, and dynamic variability within the subtropical marine boundary layer
Brian H. Kahn1, Georgios Matheou1, Qing Yue1, Thomas Fauchez2, Eric J. Fetzer1, Matthew Lebsock1, João Martins3, Mathias M. Schreier1, Kentaroh Suzuki4, and João Teixeira1 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
2NASA Goddard Space Flight Center, Greenbelt, MD, USA
3Instituto Português do Mar e da Atmosfera, Lisbon, Portugal
4Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
Abstract. The global-scale patterns and covariances of subtropical marine boundary layer (MBL) cloud fraction and spatial organization with atmospheric thermodynamic and dynamic fields remain poorly understood. We describe a novel approach that leverages coincident NASA A-train and the Modern Era Retrospective-Analysis for Research and Applications (MERRA) data to quantify the relationships in the subtropical MBL derived at the native pixel and grid resolution. Four subtropical oceanic regions that capture transitions from closed-cell stratocumulus to open-cell trade cumulus are investigated. We define stratocumulus and cumulus regimes based exclusively from infrared-based thermodynamic phase. Visible reflectances are normally distributed within stratocumulus and are increasingly skewed away from the coast where disorganized cumulus dominates. Increases in MBL depth, wind speed and effective radius (re), and reductions in 700–1000 hPa moist static energy differences and 700 and 850 hPa vertical velocity, correspond with increases in reflectance skewness. We posit that a more robust representation of the cloudy MBL is obtained using visible reflectance rather than retrievals of optical thickness that are limited to a smaller subset of cumulus. An increase in re within shallow cumulus is strongly related to higher MBL wind speeds that further correspond to increased precipitation occurrence according to CloudSat. Our results are consistent with surface-based observations and suggest that the combination of A-train and MERRA data sets have potential to add global context to our process understanding of the subtropical cumulus-dominated MBL.

Citation: Kahn, B. H., Matheou, G., Yue, Q., Fauchez, T., Fetzer, E. J., Lebsock, M., Martins, J., Schreier, M. M., Suzuki, K., and Teixeira, J.: A satellite and reanalysis view of cloud organization, thermodynamic, and dynamic variability within the subtropical marine boundary layer, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-59, in review, 2017.
Brian H. Kahn et al.
Brian H. Kahn et al.
Brian H. Kahn et al.

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Short summary
The global-scale patterns of subtropical marine boundary layer clouds are investigated with coincident NASA A-train satellite and reanalysis data. This study is novel in that all data is used at the finest spatial and temporal resolution possible. Our results are consistent with surface-based data and suggest that the combination of satellite and reanalysis data sets have potential to add to the global context of our understanding of the subtropical cumulus-dominated marine boundary layer.
The global-scale patterns of subtropical marine boundary layer clouds are investigated with...
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