28 Oct 2022
28 Oct 2022
Status: this preprint is open for discussion.

Distinct regional meteorological influences on low cloud albedo susceptibility over global marine stratocumulus regions

Jianhao Zhang1,2 and Graham Feingold2 Jianhao Zhang and Graham Feingold
  • 1Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA
  • 2Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration (NOAA), Boulder, CO, USA

Abstract. Marine stratocumuli cool the Earth effectively due to their high reflectance of incoming solar radiation, and persistent occurrence. The susceptibility of cloud albedo to droplet number concentration perturbations depends strongly on large-scale meteorological conditions. Studies focused on the meteorological dependence of cloud adjustments often overlook the covariability among meteorological factors and their geographical and temporal variability. We use 8 years of satellite observations sorted by day and geographical location to show the global distribution of marine low cloud albedo susceptibility. We find an annual mean cloud brightening potential for most of the regions, more pronounced over subtropical coastal regions. Weak cloud darkening potential in the annual mean is evident over the remote SE Pacific and SE Atlantic. We show that large-scale meteorological fields from the ERA5 reanalysis data, including lower-tropospheric stability, free-tropospheric relative humidity, sea surface temperature, and boundary layer depth, have distinct covariabilities over each of the eastern subtropical ocean basins where marine stratocumulus prevail. This leads to markedly different monthly evolution in albedo susceptibility over each basin. Moreover, we find that basin-specific regional relationships between key meteorological factors and albedo susceptibilities are absent in a global analysis. Our results stress the importance of considering the geographical distinctiveness of temporal meteorological covariability when scaling up the local-to-global response of cloud albedo to aerosol perturbations.

Jianhao Zhang and Graham Feingold

Status: open (until 09 Dec 2022)

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Jianhao Zhang and Graham Feingold

Jianhao Zhang and Graham Feingold


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Short summary
Using observations from the space, we show maps of potential cloud brightness changes in response to increases in cloud droplets. We find that the environmental conditions in which these cloud reside covary in time differently from one part of the world to another, leaving distinct regional fingerprints of cloud brightness changes, which are absent when data is aggregated globally. We stress the importance of embracing, instead of untangling, the covariability between meteorology and aerosol.