This data set consists of apparent surface reflectance, subpixel snow-covered area and grain size inferred from data acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The AVIRIS has a spectral range of 400-2500 nm, a spectral resolution of 10 nm, instantaneous field of view of 1 mrad, and a scan angle of 15 degrees. Sampling is scene based (~ 815 samples, 512 lines). The AVIRIS provides spectral resolution into hundreds of spectral bands versus the seven multispectral bands flown on traditional Landsat imaging missions. Through this large number of spectral bands, complex land ecosystems can be imaged and accurately classified. This data set is part of the NASA Cold Land Processes Field Experiment (CLPX). The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread. Data are available via FTP. Users are requested to register with NSIDC User Services to obtain access to the data.

The Rapid Update Cycle analysis/model system at a 20-km horizontal resolution (RUC20) provides short-range numerical weather guidance for general forecasting, as well as for the special short-term needs of aviation and severe-weather forecasting. This data set consists of 60 meteorological and soil parameters at 50 computational levels. Data are available from 1 October 2002 to 1 October 2003. RUC20 is a further development on the RUC40 model that produced output at a 40 km horizontal resolution. The NASA Cold Land Processes Experiment (CLPX) is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

Airborne Synthetic Aperture Radar (AIRSAR) is a side-looking imaging radar that is able to collect data irrespective of daylight or cloud cover. The AIRSAR instrument was operated in two modes over each Cold Land Processes Field Experiment (CLPX) Meso-cell Study Area (MSA). In the first mode (POLSAR), polarimetric radar data were collected at P-, L-, and C-bands. In the second mode (TOPSAR), cross-track interferometry data were collected at C-band and L-band. The CLPX AIRSAR mission flew on a DC-8 aircraft at 8 km altitude over the three MSAs at Rabbit Ears, North Park, and Fraser. 171 flight lines (87 TOPSAR and 84 POLSAR) were flown in February, March, and September of 2002 and in March 2003. The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

This data set presents micrometeorological data from the Flux over Snow Surfaces (FLOSS) project carried out during the Cold Land Processes Field Experiment (CLPX) at North Park, Colorado, USA. The project measured air temperature, air pressure, relative humidity, water vapor, cloud particles, carbon dioxide, longwave and shortwave radiation, and precipitation. Measurements were collected between November 2002 and March 2003. Sensors were installed on a Raytheon King Air 200T, which flew at low atlitude over the study area.

This data set contains Ku-band polarimetric scatterometer (POLSCAT) data collected as part of the Cold Land Processes Field Experiment (CLPX) to enable the development of a retrieval algorithm for snow water equivalent (SWE). POLSCAT is a Ku-band polarimetric scatterometer operating at 13.95 GHz. Flights were flown on 19, 21, and 23 February 2002 (during IOP1), 25 March 2002 (IOP2), and 25, 28 and 30 March 2003 (IOP 4). 205 flight lines of data were collected over Fraser, North Park and Rabbit Ears MSAs. The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

This data set is comprised of FMCW radar measurements, which are sensitive to electromagnetic discontinuities in the snowpack, made during the 2002 and 2003 Cold Land Processes Field Experiment (CLPX). The microwave interaction with a snow pack was measured using broadband frequency modulated continuous wave (FMCW) radar operating at between 2 and 18 GHz, incorporating the following frequencies: C-Band (2-6 GHz), X-Band (8-12 GHz), and Ku-Band (14-18 GHz). Measurements were made at the Local Scale Observation Site (LSOS) near Fraser, Colorado, during Intensive Observation Periods (IOP) 1 and 2 (February and March, 2002), and at four different sites covering each of the three Mesocell Study Areas (MSAs) during IOP 3 and 4 (February and March, 2003). Active microwave radar signals are reflected and scattered by electromagnetic discontinuities that affect radar backscatter signatures. The location and magnitude of these discontinuities in a snow pack must be identified as a function of microwave frequency in order to accurately invert snow cover properties from active and passive microwave remote sensing systems. Consequently, in conjunction with the radar measurements, detailed snow pit measurements were taken at a nearby site in order to correlate the radar profile with the snow pit records. This investigation found that radar operating at 14-18 GHz contains the most information about the internal features of a dry snow pack. However, the high-frequency radar is of limited use in wet snow due to the high absorption loss in water. For a wet snowpack, radar operating at lower frequencies (2-6 GHz) was necessary for penetrating to the snow-ground interface. These findings suggest that a dual-frequency approach for radar remote sensing may be necessary to retrieve snow pack parameters such as density, depth, and wetness. The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

This data set includes ground-based radar observations carried out at the Fraser Experimental Forest Headquarters, Colorado, USA (39.95 N, 105.9 W), between 17-26 February and 26-30 March 2003. Truck-mounted L- and Ku-band scatterometers were used to collect fully polarimetric backscattering coefficients of snow. The calibrated radar systems measured the amplitude and phase of backscattered signal over a relatively wide bandwidth at L-band (1.1-1.4 GHz) and Ku-band (15.25-15.75 GHz). Backscatter measurements of an open snow pack were collected at three different incidence angles (20, 35, and 50 degrees) several times a day. This data set is part of the NASA Cold Land Processes Field Experiment (CLPX). The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

This data set contains meteorological observations at ten sites throughout the Small Regional Study Area (SRSA) of the Cold Land Processes Field Experiment (CLPX) in Fraser, Colorado, USA. Nine identical meteorological towers were located close to the center of each Intensive Study Area (ISA). Another meteorological tower was located close to the Local-Scale Observation Site (LSOS) within the Fraser Meso-Cell Study Area (MSA). At each site, measurements were made at 10 m above ground level (air temperature, relative humidity, radiation, leaf wetness, wind speed, and direction); approximately 1 m above maximum anticipated snow depth (air temperature, relative humidity, wind speed, wind direction and, in the North Park MSA only, precipitation); and snow depth, snow surface temperature, snow temperature profile, soil moisture, and soil temperatures. Snow pits were also dug at the meteorological sites, and snow density, temperature, and stratigraphy were recorded. Meteorological observations were recorded at a 10-minute temporal resolution between 20 September 2002 and 1 October 2003, although data were not necessarily continuous throughout this time period for all towers. Meteorological measurements were made to support investigations of spatial and temporal variations in accumulation and ablation of the seasonal snowpack within the study areas. The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

This data set consists of snow pit data from nine study areas, within three larger-scale areas in northern Colorado (Fraser, North Park, and Rabbit Ears Meso-cell Study Areas (MSAs)). The study areas range from low-relief (flat topography) unforested areas with shallow snow covers, to high-relief (complex topography) densely forested areas with deep snow covers. Parameters measured include snow density, snow temperature, snow stratigraphy, and snow grain size. Data were collected during February and March 2002 and 2003. This data set is part of the NASA Cold Land Processes Field Experiment (CLPX).

This data set includes two sets of soil temperature profiles, two sets of soil moisture profiles, two sets of soil heat flux profiles (in dense pine and open pine areas), and one set of a snow temperature profile, air temperature, and relative humidity measurements. Measurements were made at the Local Scale Observation Site (LSOS) of the Cold Land Processes Field Experiment (CLPX) in northern Colorado. The LSOS is a 100 m x 100 m study site located within the Fraser Intensive Study Area (ISA). The study area has flat topography with a uniform pine forest, a discontinuous pine forest, and a small clearing. Data were collected between 6 November 2002 and 29 May 2003. These data were primarily collected to support the University of Michigan microwave radiometric observations acquired at the same site (to be published in early 2004).

This data set presents micrometeorological data from the Flux over Snow Surfaces (FLOSS) project carried out during the Cold Land Processes Field Experiment (CLPX) at North Park, Colorado, USA. The project measured air temperature, air pressure, relative humidity, wind speed, water vapor flux, carbon dioxide, longwave and shortwave radiation, soil temperature, soil moisture, soil heat flux, precipitation, snow depth, and eddy correlation. Measurements were collected between 1 Dec 2001 and 27 March 2002, and between 20 November 2002 and 24 March 2003. Sensors were installed on a 24-meter tower, and on 2-meter and 4-meter platforms.

This data set consists of solar and longwave radiation data from beneath two pine canopies (one uniform, one discontinuous) at the Local Scale Observation Site (LSOS) of the Cold Land Processes Field Experiment (CLPX) in northern Colorado. The LSOS is a 100 x 100-m study site located within the Fraser Intensive Study Area (ISA). The study area has flat topography with both a dense pine stand and an open pine stand. Data were collected during February and March 2002 and 2003. This work addresses two of the overall CLPX questions: (1) How do the extent and evolution of snow and frozen landscapes affect fluxes, storage, and transformations of water, energy, and carbon? (2) At what scales does spatial variability of key state variables in the cryosphere (including snow characteristics, soil moisture, the extent of frozen soils, and the transition between frozen and thawed conditions) control fluxes and transformations of water, energy, and carbon, and can remote sensing resolve this variability at these scales? The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

The LDAS data set contains 43 model and observation-based fields produced by the LDAS uncoupled modeling system at the NASA Goddard Space Flight Center using the Mosaic Land Surface Model (LSM). Parameters include snow cover, snow depth, snow melt, albedo, precipitation, temperature, canopy characteristics, longwave and shortwave radiation, heat flux, soil moisture, sublimation, snow water equivalent, and meteorolical parameters. Precipitation and solar radiation are observation-based, while other forcing variables (humidity, temperature, wind speed, pressure, longwave radiation) are derived from the National Centers for Environmental Prediction’s (NCEP) Eta Data Assimilation System (EDAS). All other variables in the files are from the Mosaic LSM. Data were produced at an hourly resolution from 1 January 2001 through June 2003. The LDAS data are delivered on an 1/8th-degree regular latitude/longitude grid covering the Large-Regional Study Area (LRSA), located between 38.5-42 N and 104-108.5 W. The resolution in the Y direction of each 1/8th degree LDAS pixel is 13899 meters over the whole domain. The resolution in the X direction ranges from 10878 meters at the southern edge of the LRSA to 10329 meters at the northern edge of the LRSA (it decreases as the distance between longitude lines decreases). Data are available via ftp on request. The NASA Cold Land Processes Experiment (CLPX) is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

The Rapid Update Cycle, version 2 at 40km (RUC-2, known to the Cold Land Processes community as RUC40) model is a Mesoscale Analysis and Prediction System (MAPS) data set that uses the Model Output Reduced Data Set (MORDS) version. This data set has been subsetted for use in the Cold Land Processes Field Experiment (CLPX). The data are in a 40 km (approximate) Lambertian latitude/longitude grid covering the Large-Regional Study Area (LRSA).The data set covers the period from 1 October 2002 through 30 June 2003, with a time step of 60 seconds. RUC40 data are stored in individual ASCII data files, with one file per hour. Within each hourly file, 42 data variables are stored in row-major order. The RUC40 model uses the Arakawa-C staggered horizontal grid, with u and v horizontal wind points offset from mass points to improve numerical accuracy, and there is no vertical staggering. Positive definite advection schemes are used for the continuity equation (advection of pressure thickness between levels) and for horizontal advection of virtual potential temperature, and all vapor and hydrometer moisture variables.

This data set includes AVHRR/HRPT (Advanced Very High Resolution Radiometer/High Resolution Picture Transmission) brightness temperatures and reflectances over the NASA Cold Land Processes Field Experiment (CLPX) Large Regional Study Area (LRSA) (NW corner: 42°N, 108.5°W, SE corner: 38.5°N 104°W). Data are gridded to the LRSA at 1.1 km (or 30 arc-second) resolution. Data were collected between November 2001 and May 2003. Reflectance files contain flat binary rasters of 2-byte unsigned integers representing albedo. The brightness temperature files contain 2-byte unsigned integers representing interpolated temperatures in tenths of degrees Kelvin.

This data set consists of Lansat thematic mapper imagergy collected over the Cold Land Processes Field Experiment (CLPX) Large Regional Study Area (LRSA), located between 104-108.5 W and 38.5-42 N. Data were collected between 10 November 2001 and 9 January 2003, using the Enhanced Thematic Mapper Plus sensor (ETM+) on Landsat 7 and the Thematic Mapper (TM) sensor on Landsat 5. Data consist of Level 1G imagery products (radiance) that have been radiometrically and geometrically corrected. Each band of Landsat data in the GeoTIFF format is delivered as a greyscale, uncompressed, 8-bit string of unsigned integers. This data set is part of the NASA CLPX NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

This data set includes Level-1B1radiance (all angles), Level-1B2 georectified terrain, and Level-2 land surface, and an ancillary geographic product for the Large Regional Study Area (LRSA) of the Cold Land Processes Field Experiment (CLPX) in northern Colorado and southern Wyoming. Data were collected between 15 February and 15 May 2002 and the same time period in 2003. Data are available via FTP. The Multi-angle Imaging SpectroRadiometer (MISR) views Earth at nine widely spaced angles via radiometrically and geometrically calibrated images in four spectral bands at each of the nine angles, to provide global images with high spatial detail. Global spatial sampling is provided at 275 and 1100 meters. These images provide accurate measures of the brightness, contrast, and color of reflected sunlight.