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Projects > A - C > CLPX

Preferred term

CLPX  

Definition

  • 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] (en)

Broader concept

URI

https://gcmd.earthdata.nasa.gov/kms/concept/bd3a3836-034d-4e19-84f0-96cec3473596

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