Scientific Colloquium
May 25, 2016, 3:30 p.m., Building 3 Auditorium
GRAHAM
FEINGOLD
NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION
"Quantifying
Aerosol Influences on the Cloud Radiative Effect"
Although evidence of aerosol influences on the microphysical
properties of shallow liquid cloud fields abounds, a rigorous
assessment of aerosol effects on the radiative
properties of these clouds has proved to be elusive
because of adjustments in the evolving cloud system. We
will demonstrate through large numbers of idealized large eddy
simulation and 14 years of surface-based remote sensing at a
continental US site that the existence of a detectable cloud
microphysical response to aerosol perturbations is neither a
necessary, nor a sufficient condition for detectability of
a radiative response. We will use a new framework that
focuses on the cloud field properties that most influence
shortwave radiation, e.g., cloud fraction, albedo, and
liquid water path. In this framework, scene albedo is
shown to be a robust function of cloud fraction for a variety of
cloud systems, and appears to be insensitive to averaging scale.
The albedo-cloud fraction framework will be used to
quantify the cloud radiative effect of shallow liquid clouds and
to demonstrate (i) the primacy of cloud field properties such as
cloud fraction and liquid water path for driving the cloud
radiative effect; and (ii) that the co-variability between
meteorological and aerosol drivers has a strong influence on the
detectability of the cloud radiative effect, regardless of
whether a microphysical response is detected. A broad
methodology for systematically quantifying the cloud radiative
effect will be presented.
About the Speaker:
Graham Feingold is a research scientist at NOAA's Earth System
Research Laboratory in Boulder, Colorado. His interests lie in
aerosol-cloud-precipitation interactions and implications for
climate change. His focus is on process level studies using high
resolution models and observations (aircraft and surface remote
sensing) at the cloud scale (10s of meters to 10s of kms). He
received his PhD in Geophysics and Planetary Sciences (summa cum
laude) from the Tel Aviv University in 1989. His research
interests include lidar and radar remote sensing of clouds and
aerosol, modeling and remote sensing of aerosol-cloud
interactions ("indirect effects"), "cloud burning" or the
"semi-direct effect," and cloud processing of aerosol through
multiphase chemistry. He has authored or co-authored more than
150 peer-reviewed articles on these subjects. Feingold was a
lead author on the IPCC AR5 Chapter 7 (Clouds and Aerosols), and
is an associate editor of the online journal Atmospheric
Chemistry and Physics (ACP), a contributor to the Climate Change
Science Program, and a chapter author of the International
Aerosol-Precipitation Scientific Assessment Project. He has
served as a NOAA representative to EarthCare and IGAC and is
currently on the Aerosol-Cloud-Precipitation-Climate (ACPC)
steering committee.
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