2011 - Cooperative Institute for Research in Environmental Sciences ...

Milestone 3. Apply a CloudSat method for simultaneous
retrievals of mean rain rate and ice water path in
stratiform precipitating systems to multi-year data sets
collected during the CloudSat overpasses in the vicinity
of the ARM Southern Great Plains Climate Research
Facility (ACRF). The CloudSat retrievals will be analyzed
for possible correlations between parameters of the ice
parts of precipitating systems (e.g., ice water path) and
the resultant rainfall. The satellite retrievals will be also
compared to the ARM retrievals, so a consistency between
space-borne and ground-based estimates of hydrometeor
parameters in precipitating cloud systems will be investigated.
A method to retrieve ice water path (IWP), mean rainfall
rate and cloud liquid water path (CLWP) in the same
vertical atmospheric column was developed and initially
applied for stratiform-like precipitation events observed
at the Southern Great Plains (SGP) site of the Atmospheric
Radiation Measurement (ARM) Program. The retrieval
method is based on multi-frequency radar measurements
at W-, Ka and S-band. The radar measurements
also provide a robust separation of the liquid, mixed and
ice hydrometeor layers. Applying the method to case
studies indicates that characteristic values of CLWP are
about 300-400 g/m2, although values up to 1,000 g/m2
and higher are not uncommon. IWP, which represents the
precipitating cloud part of the atmospheric column that
is observed above the freezing level, usually significantly
exceeds cloud liquid water path and can reach values of
approximately 10,000 g/m2 and even higher. There is lowto-medium
correlation between IWP and mean rain rate.
On average, mean rainfall in the liquid layer, R, increases
with an increase in ice mass observed above the melting
layer. Figure 1 shows an example of retrievals.
Figure 2: Example of a retrieval.
Milestone 4. Maintain configurations and web access to
the real-time water vapor flux tool for use by researchers
and weather forecasters to assess and monitor extreme
precipitation events along the West Coast of the United
States.
In support of the near-real-time water vapor flux tool,
which is used by researchers and forecasters to help monitor
and study extreme orographic precipitation events,
104 CIRES Annual Report 2011
automated software operations and configurations were
maintained for 10 different NOAA and cooperative agency
sites along the U.S West Coast. The maintenance and
configuration of software to distribute the tool’s numerical
flux data was also performed. Lastly, monitoring of data
and product quality as well as near-real-time availability
was accomplished on a daily basis to support research and
forecasting efforts during the NOAA HMT and CalWater
campaigns.
Milestone 5. The CalWater experiment is a multi-year
effort supported by NOAA and the California Energy Commission
to study the impact of anthropogenic aerosols
and climate change on precipitation and associated water
supply in California. Aerosol and meteorological observing
instruments will be deployed in key locations in California.
Part of this effort will be to diagnose the vertical
structure of the precipitating cloud systems in the context
of collocated aerosol observations. Another part of this
effort will entail analysis of meteorological observations
to characterize the Sierra barrier jet, its modulation by
atmospheric rivers and the resultant spatio-temporal
distribution of precipitation.
During the first year of the CalWater experiment, a major
accomplishment was the installation of NOAA radars and
surface meteorological instruments at three field sites in
California for the 2010-2011 winter season field campaign.
The sites included Sugar Pine Dam, Mariposa airport and
Lincoln airport. Researchers from the University of California
at San Diego installed aerosol sampling instruments
at all three sites. While the first year of CalWater focused
on collecting data during the 2010-2011 winter season field
campaign, next year will focus on analyzing and interpret-
NOAA instrumentation at the Mariposa airport during sunset. From left
to right, the photo shows a vertically pointing S-band (2.8 GHz) profiling
radar, a Parsivel disdrometer and an anemometer mounted on a 10-m
tower.