SHEBA May 4 aircraft flight shown projected upon a cloud radar
reflectivity time-height diagram, relative to the lidar-determined water
cloud base (dotted line) and temperature inversion (solid line). see
Zuidema et al. (2005) for further explanation.
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The Arctic: An important result from the
Surface Heat Budget of the Arctic experiment is that clouds
are often mixed-phase. While the liquid component is primarily
responsible for the cloud optical depth and thereby the
radiative cloud forcing at the surface, ice initiation acts
to regulate the presence of liquid. I am working to provide
observational constraints on ice-initiation processes using SHEBA data.
Inspired by the radiative importance of the liquid phase, Robert Joyce and I
evaluated satellite microwave-derived liquid water path
climatologies and trends over the northern high latitude open seas
(paper).
These on-going projects were funded under a NASA Interdisciplinary Studies grant.
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Zuidema et al. (2006) is a writeup of the
EPIC analysis and
Zuidema and Mapes (2008) of the JASMINE
analysis |
The Tropics: Tropical clouds attain complex structures, reflective
of the many processes that help form them. I am elucidating tropical cloud
vertical structure from two tropical oceaninc field campaigns.
Within the eastern tropical Pacific, mid-tropospheric dry
air of equatorial origin can impinge upon and feedback with overlying cirrus
anvils. In contrast, within the Bay of Bengal the atmospheric moisture
distribution switches completely from dry to moist at monsoon onset, with two
highly different associated cloud vertical structures. The different
behaviors are evident in cloud radar reflectivities shown overlain with rawindsonde
relative humidities and winds and contours of the divergence calculated from
coincident precipitation radar, along with measured surface rainfall rates.
Eastern Pacific Investigation of Climate (EPIC) (11 Mb pdf)
Joint Air-Sea Monsoon Experiment (JASMINE; Bay of Bengal)
(12 Mb pdf). Note to other researchers: The EPIC data are publicly available through
http://catalog.eol.ucar/edu/epic. The JASMINE data are also publicly available but
harder to find. Try http://www.esrl.noaa.gov/psd and http://www.atmos.washington.edu/MG/JASMINE/jasmine.html.
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Zuidema et al. (2005) contains
an assessment of surface-based liquid water paths gathered during the
EPIC stratocumulus leg. |
The Subtropics: The relationship between subtropical boundary-layer cloud
properties, precipitation, and aerosol is still not well-understood.
Under a NOAA grant,
David Painemal
and I are working with data from
buoy-tending cruises to the southeastern Pacific stratus region to
elucidate these associations and assess satellite-retrieved information
with ship-based data. These almost-annual cruises are conducted by
Chris Fairall (see http://www.esrl.noaa.gov/psd/psd3/).
A few papers on this are on my publications website. In another NASA-funded project I assessed the
three-dimensional radiative transfer behavior of trade-wind Cumulus under varying aerosol
regimes using cloud data from LES simulations undertaken by primarily by Huiwen Xue and Graham
Feingold(paper). In a related project,
Zhujun Li is forcing different
commonly-used microphysical schemes with RICO lidar-observed vertical velocities, towards developing
an opinion on which one we like best.
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Mean diurnal cycle in sonde relative humidity and ceilometer cloud
base heights over the southern Gulf of California during NAME, described more
fully in Zuidema et al. (2007). |
Field investigations in the Southeastern Pacific stratocumulus region and the North
American Monsoon highlight the importance of light evaporating precipitation to the
dynamics of each region. A confident knowledge of the precipitation and its flux remain
lacking for both regions. A NOAA (2007) project is addressing this through developing a
precipitation retrieval for both locations from vertically-pointing lidar (ceilometer) data,
with help from Chris Brodowski.
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