Snow dielectric measurements

Denoth, A.

doi:10.1016/0273-1177(89)90491-2

Cited by 77 publications

(72 citation statements)

References 17 publications

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“…A comprehensive analysis of these parameters is beyond the scope of this paper. A snow surface dielectric capacitance probe and measurements of snow density were used to derive snow wetness as a percentage of the volume at different depths (Denoth, 1989). Surface and near-surface wetness values were averaged from multiple measurements at each site, and these wetness values were later compared with AMSR-E 36Ð5V GHz T b from overpasses obtained less than 1 h before or after the ground observations ( Figure 5(a) and (b), Table III).…”

Section: Ramagementioning

confidence: 99%

AMSR‐E algorithm for snowmelt onset detection in sub‐arctic heterogeneous terrain

Apgar

Ramage

McKenney

et al. 2007

Hydrological Processes

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Abstract:The onset of snowmelt in the upper Yukon River basin, Canada, can be derived from brightness temperatures (T b ) obtained by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on NASA's Aqua satellite. This sensor, with a resolution of 14 ð 8 km 2 for the 36Ð5 GHz frequency, and two to four observations per day, improves upon the twice-daily coverage and 37 ð 28 km 2 spatial resolution of the Special Sensor Microwave Imager (SSM/I). The onset of melt within a snowpack causes an increase in the average daily 36Ð5 GHz vertically polarized T b as well as a shift to high diurnal amplitude variations (DAV) as the snow melts during the day and re-freezes at night. The higher temporal and spatial resolution makes AMSR-E more sensitive to sub-daily T b oscillations, resulting in DAV that often show a greater daily range compared to SSM/I. Therefore, thresholds of T b > 246 K and DAV > š10 K developed for use with SSM/I have been adjusted for detecting the onset of snowmelt with AMSR-E using ground-based surface temperature and snowpack wetness relationships. Using newly developed thresholds of T b > 252 K and DAV > š18 K, AMSR-E derived snowmelt onset correlates well with SSM/I observations in the small subarctic Wheaton River basin through the 2004 and 2005 winter/spring transition. In addition, the onset of snowmelt derived from AMSR-E data gridded at a higher resolution than the SSM/I data indicates that finer-scale differences in elevation and land cover affect the onset of snowmelt and are detectable with the AMSR-E sensor. On the basis of these observations, the enhanced resolution of AMSR-E is more effective than SSM/I at delineating spatial and temporal snowmelt dynamics in the heterogeneous terrain of the upper Yukon River basin.

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Section: Ramagementioning

confidence: 99%

AMSR‐E algorithm for snowmelt onset detection in sub‐arctic heterogeneous terrain

Apgar

Ramage

McKenney

et al. 2007

Hydrological Processes

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“…The snowpack was more homogeneous and showed less horizontal layering than at the time of the 1989 survey. Profiles of wetness were measured in 5 cm intervals with a dielectric wetness meter operating at 20 MHz with a flat-plate sensor (Denoth, 1989). The liqu id water conten t of the top snow layers was similar during both AIRSAR surveys.…”

Section: Snowpack Propertiesmentioning

confidence: 99%

Multifrequency and polarimetric SAR observations on alpine glaciers

Rott

Davis

1993

A. Glaciology.

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ABSTRACT. The glacier-covered test site Rofental in the Austrian Alps was surveyed by the AIRSAR of the NASA/J et Propulsion Laboratory in August 1989 and June 1991 . A few days after the AIRSAR survey in 1989 Landsat TM and SPOT images were acquired, which provide the opportunity to compare visible and radar data. Field activities during the SAR surveys included measurements of dielectrical, structural, and surface roughness properties and the deployment of corner reflectors. After polarimetric and radiometric calibration of the SAR data, polarimetric signatures of th e main target types, snow, glacier ice and moraines, were derived . Pronounced effects of surface roughness were observed at C-and L-band for artificially roughened snow surfaces. Parallel AIRSAR swaths of the 1991 survey provide the basis for studies of incidence angle effects. Due to the increasing penetration depth , the unpolarized backscattering components of the wet snow areas increase from the C-to the P-band. The multifrequency backscattering properties of the various surfaces offer the best means for target discrimination.

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“…Denoth, 1989) or snow forks (e.g. Sihvola and Tiuri, 1986), the precise determination of vertical profiles of snow grain SSA and stratigraphy (layering) using a lightweight optical system is essential for improving snow and radiative transfer models.…”

Section: Resultsmentioning

confidence: 99%

New shortwave infrared albedo measurements for snow specific surface area retrieval

Montpetit¹,

Royer²,

Langlois³

et al. 2012

J. Glaciol.

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ABSTRACT. Snow grain-size characterization, its vertical and temporal evolution is a key parameter for the improvement and validation of snow and radiative transfer models (optical and microwave) as well as for remote-sensing retrieval methods. We describe two optical methods, one active and one passive shortwave infrared, for field determination of the specific surface area (SSA) of snow grains. We present a new shortwave infrared (SWIR) camera approach. This new method is compared with a SWIR laserbased system measuring snow albedo with an integrating sphere (InfraRed Integrating Sphere (IRIS)). Good accuracy (10%) and reproducibility in SSA measurements are obtained using the IRIS system on snow samples having densities greater than 200 kg m -3 , validated against X-ray microtomography measurements. The SWIRcam approach shows improved sensitivity to snow SSA when compared to a near-infrared camera, giving a better contrast of the snow stratigraphy in a snow pit.

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Snow dielectric measurements

Cited by 77 publications

References 17 publications

AMSR‐E algorithm for snowmelt onset detection in sub‐arctic heterogeneous terrain

AMSR‐E algorithm for snowmelt onset detection in sub‐arctic heterogeneous terrain

Multifrequency and polarimetric SAR observations on alpine glaciers

New shortwave infrared albedo measurements for snow specific surface area retrieval

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