About the CloudSat Validation Plan...
It is well known that Earth's radiation budget
is modulated significantly by clouds, and that
seemingly small, but systematic, changes to cloud
properties can affect important changes to global
and regional climate. While much progress has
been made recently on the radiative transfer end
of the problem, there is still much uncertainty
with respect to whether global climate models
are doing a good job when it comes to simulating
and diagnosing cloud properties. It is expected
that data from the NASA/CSA
CloudSat satellite mission, with a 94 GHz
cloud-profiling radar, used in synergy with data
from several other satellites will help guide
future development of cloud routines in climate
and weather models.
CloudSat was launched on 28
April 2006 along with the CALIPSO satellite
which carries a backscattering lidar and passive
imagers. Both satellites will fly in formation
with Aqua that carries the MODIS instrument as
part of the so-called A-train.
An overview of the CloudSat mission is given
in a
BAMS article by Stephens et al (2002).
It is anticipated that the combination of the
3 satellites as well as model analyses made at
ECMWF will provide the first global survey of
vertically resolved cloud properties. This data
will include cloud macroscopic characteristics,
the vertical and horizontal distributions of cloud
water and ice contents, cloud particle phase,
a representative size of the cloud particles and
some details on precipitation. Such information
is crucial for diagnosing cloud parameterizations
by weather forecast and climate models.
As part of the international CloudSat program,
the Meteorological Service of Canada (MSC),
Environment Canada, will be performing extensive
validation of the satellite products in the context
of the Canadian climate. The goals will be to,
- Provide the independent verification of the
products
- Verify the physical basis of the algorithms
of the data products as they apply to cold season
cloud systems
- Contribute to the development of new 'mid/high
latitude products' e.g. snow retrievals
- Put this analysis into the perspective of
weather systems and large-scale circulations
There will be four main foci involved in this
activity. They are,
- The development of an end-to-end
radiation simulator. Similar activities
associated with EarthCARE
will be built upon to include data from ground-based
and aircraft platforms.
- Carry out detailed field measurements in south
central Ontario. This will include ground-based
measurements at the Centre of Atmospheric Research
Experiments (CARE)
with an array of in-situ and remote sensing
instrumentation that includes a lidar, a cloud
radar, a wind profiler, a precipitation radar
and a microwave radiometer. Also, the NRC
Convair-580 research aircraft, containing
a suite of in-situ and remote sensing sensors,
will fly missions along CloudSat's ground track.
The goal is to fly from two to four missions
for
each 16 day cycle of satellite orbits. The
enhanced surface measurements will take place
from November to April during the two year lifetime
of the mission. The aircraft campaign will encompass
approximately 90 hours of flying.
- To collaborate with the PEARL
initiative to obtain additional information,
similar in scope to that obtained at CARE, on
high latitude cloud systems at Eureka.
The Arctic aspect will not have an aircraft
component.
- For the validation exercise will take advantage
of the EC weather
observing network, the POSS
observing network, and the Doppler
radar network.
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