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Cold Land Processes Field Experiment

Project Description
The Cold Land Processes Field Experiment will focus on
developing the quantitative understanding, models, and
measurements necessary to extend our local-scale understanding
of water fluxes, storage, and transformations to regional and
global scales. The experiment will particularly emphasize
developing a strong synergism between process-oriented
understanding, land surface models and microwave remote sensing.

Microwave sensors appear ideal to measure properties of the
terrestrial cryosphere because the microwave signal is
sensitive to the dielectric constant of surface materials,
which in turn is sensitive to the phase of water, ice or liquid
[Koh, 1992]. Passive microwave sensors are sensitive to the
physical temperature of surface materials. Both active and
passive microwave sensors have demonstrated sensitivity to snow
properties and the freeze/thaw status of soils [Goodison and
Walker, 1993; Chang, et al., 1996; Shi and Dozier,
2000]. Microwave signal response is influenced by snow depth,
density, wetness, crystal size and shape, ice crusts and layer
structure, surface roughness, vegetation characteristics, soil
moisture, and soil freeze/thaw status [Davis et al., 1987; Hall
et al., 1986; McDonald and Ulaby, 1993; Josberger et al., 1996,
Kim, 1999; Rosenfeld and Grody, 2000]. While visible and
near-infrared sensors cannot see through clouds and require
adequate solar illumina! tion, which is a frequent and severe
limitation in cold regions during winter [Cline and Carroll,
1999], measurements of the Earth surface in the microwave
spectral regions can be largely insensitive to weather
conditions and solar illumination. These properties make
microwave remote sensing attractive for providing spatially
distributed information to improve and update land-surface
models for cold regions, either through assimilation of
state-variable information estimated from microwave remote
sensing observations using inversion algorithms, or possibly
even through direct assimilation of microwave remote sensing
data themselves.

The specific objectives of the Cold Land Processes Field
Experiment are to:

1. Evaluate and improve snow water equivalent retrieval
algorithms for space-borne passive microwave sensors
(e.g. SSM/I and AMSR-E);

2. Evaluate and improve radar retrieval algorithms for snow
depth, density, and wetness, and soil freeze/thaw status;

3. Improve radar retrieval algorithms to enable discrimination
of freeze/thaw status of different surfaces (i.e. snow, soil,
and vegetation); Examine the effects of scale (spatial
resolution) on the skill of active and passive microwave remote
sensing retrieval algorithms for snow and freeze/thaw status;

4. Evaluate and improve spatially distributed, uncoupled
snow/soil models and coupled cold land surface schemes from
point scales to typical mesoscale grid-resolutions
(i.e. 25-km);

5. Examine the feasibility of coupling forward microwave
radiative-transfer schemes to spatially distributed snow/soil
models, to improve assimilation of microwave remote sensing
data;

6. Examine the spatial variability of snow and frozen soil
distributions in different environments and a) improve the
representation of subgrid-scale variability of snow and frozen
soil in coupled and uncoupled land surface models, and b)
improve the representation of orographic precipitation
(snowfall) in atmospheric models;

7. Examine methods of extending local-scale, process-oriented
equations describing important cold-land hydrologic and
boundary layer properties to larger scales typical of regional
and global atmospheric and hydrologic models.

For more information, link to
http://www.nohrsc.nws.gov/~cline/clpx.html

[Summary provided by NASA]
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