Satellite observations of cloud regime development: the role of aerosol processes
Gryspeerdt, E; Stier, P; Partridge, DG
Date: 3 February 2014
Journal
Atmospheric Chemistry and Physics
Publisher
European Geosciences Union
Publisher DOI
Abstract
Many different interactions between aerosols and
clouds have been postulated, based on correlations between
satellite retrieved aerosol and cloud properties. Previous
studies highlighted the importance of meteorological covariations
to the observed correlations.
In this work, we make use of multiple temporally-spaced
satellite ...
Many different interactions between aerosols and
clouds have been postulated, based on correlations between
satellite retrieved aerosol and cloud properties. Previous
studies highlighted the importance of meteorological covariations
to the observed correlations.
In this work, we make use of multiple temporally-spaced
satellite retrievals to observe the development of cloud
regimes. The observation of cloud regime development allows
us to account for the influences of cloud fraction (CF)
and meteorological factors on the aerosol retrieval. By accounting
for the aerosol index (AI)-CF relationship, we reduce
the influence of meteorological correlations compared
to “snapshot” studies, finding that simple correlations overestimate
any aerosol effect on CF by at least a factor of two.
We find an increased occurrence of transitions into the
stratocumulus regime over ocean with increases in MODIS
AI, consistent with the hypothesis that aerosols increase stratocumulus
persistence. We also observe an increase in transitions
into the deep convective regime over land, consistent
with the aerosol invigoration hypothesis. We find changes in
the transitions from the shallow cumulus regime in different
aerosol environments. The strength of these changes is
strongly dependent on Low Troposphere Static Stability and
10 m windspeed, but less so on other meteorological factors.
Whilst we have reduced the error due to meteorological
and CF effects on the aerosol retrieval, meteorological covariation
with the cloud and aerosol properties is harder to
remove, so these results likely represent an upper bound on
the effect of aerosols on cloud development and CF.
Mathematics and Statistics
Faculty of Environment, Science and Economy
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