Thesis (M.S.)--Ohio State University, 1982. / Includes bibliographical references (leaves 56-59). Available online via OhioLINK's ETD Center.

Utilising extensive field observations and physically-based simulations of forest-snow processes, the impacts of needleleaf forest-cover on radiation and snowmelt dynamics were investigated in an eastern Rocky Mountain headwater catchment. At low-elevation pine forest sites, the sparse canopy-cover allowed for substantial shortwave transmittance to snow, giving topography-influenced snow radiation balances and snowmelt timing. By comparison, the denser high-elevation spruce cover minimised shortwave radiation to snow, resulting in snowmelt dominated by longwave radiation gains, and close synchronisation in melt timing across opposing mountain slopes. Field observations were used to direct and evaluate physically-based simulation models describing radiation-snow exchanges in needleleaf forests. This included the estimation of shortwave irradiance transfer through sparse needleleaf canopies with explicit account for differing shortwave transmittance properties of trunks, crowns, and gaps within highly structured mountain pine stands. Improved representation of sub-canopy longwave irradiance to mountain snow was also made through the determination of added longwave emissions from shortwave heated canopies. From model simulations, forest-cover effects on radiation to snow were found to vary substantially with both topography and seasonal meteorological conditions. In general, forest-cover increased radiation during the mid-winter by reducing longwave losses from snow. However, with greater shortwave irradiance into the spring, forest-cover effects on radiation to snow became increasing influenced by topography, with greater radiation under more open canopies on south-facing slopes and under more closed canopies on north-facing slopes. Drawing upon past field investigations and modelling exercises, a physically-based simulation model was constructed to represent snow accumulation and melt processes in needleleaf forest environments. By means of an objective evaluation, the model well represented differences in snow accumulation and melt in paired forest and clearing sites of varying location and climate. The model was subsequently applied to examine forest-cover impacts on mountain snowmelt, revealing that forest-cover removal substantially increased total snowmelt and sizeably expanded the spring melt period through a de-synchronisation of melt contributions from south-facing and north-facing landscapes. These results demonstrate the potential for altering the magnitude and timing of mountain snowmelt through topographic-specific changes in mountain forest-cover.

Utilising extensive field observations and physically-based simulations of forest-snow processes, the impacts of needleleaf forest-cover on radiation and snowmelt dynamics were investigated in an eastern Rocky Mountain headwater catchment. At low-elevation pine forest sites, the sparse canopy-cover allowed for substantial shortwave transmittance to snow, giving topography-influenced snow radiation balances and snowmelt timing. By comparison, the denser high-elevation spruce cover minimised shortwave radiation to snow, resulting in snowmelt dominated by longwave radiation gains, and close synchronisation in melt timing across opposing mountain slopes. Field observations were used to direct and evaluate physically-based simulation models describing radiation-snow exchanges in needleleaf forests. This included the estimation of shortwave irradiance transfer through sparse needleleaf canopies with explicit account for differing shortwave transmittance properties of trunks, crowns, and gaps within highly structured mountain pine stands. Improved representation of sub-canopy longwave irradiance to mountain snow was also made through the determination of added longwave emissions from shortwave heated canopies. From model simulations, forest-cover effects on radiation to snow were found to vary substantially with both topography and seasonal meteorological conditions. In general, forest-cover increased radiation during the mid-winter by reducing longwave losses from snow. However, with greater shortwave irradiance into the spring, forest-cover effects on radiation to snow became increasing influenced by topography, with greater radiation under more open canopies on south-facing slopes and under more closed canopies on north-facing slopes. Drawing upon past field investigations and modelling exercises, a physically-based simulation model was constructed to represent snow accumulation and melt processes in needleleaf forest environments. By means of an objective evaluation, the model well represented differences in snow accumulation and melt in paired forest and clearing sites of varying location and climate. The model was subsequently applied to examine forest-cover impacts on mountain snowmelt, revealing that forest-cover removal substantially increased total snowmelt and sizeably expanded the spring melt period through a de-synchronisation of melt contributions from south-facing and north-facing landscapes. These results demonstrate the potential for altering the magnitude and timing of mountain snowmelt through topographic-specific changes in mountain forest-cover.

Thesis (M.S. in E.A.S.)--School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 2004. Directed by Michael H. Bergin. / Includes bibliographical references (leaves 53-56).

Rapid population growth in Arizona is leading to increasing demand and decreasing availability of water, requiring a detailed quantification of hydrological processes. The integration of detailed spatial water fluxes information from remote sensing platforms, and hydrological models is one of the steps towards this goal. One example step is the use of MODIS Snow Cover Area (SCA) information to update the snow component of a land surface model (LSM). Because cloud cover obscures the images, this project explores a rule-based method to remove the clouds. The rules include: combination of SCA maps from two satellites; time interpolation method; spatial interpolation method; and the probability of snow occurrence in a pixel based on topographic variables. The application in sequence of these rules over the Upper Salt River Basin for WY 2005 resulted in a reduction of cloud obscuration by 93.7878% and the resulting images' accuracy is similar to the accuracy of the original SCA maps. The results of this research will be used on a LSM to improve the management of reservoirs on the Salt River. This research seeks to improve SCA data for further use in a LSM to increase the knowledge base used to manage water resources. It will be relevant for regions were snow is the primary source of water supply.

No description available.

At the beginning of the International Geophysical Year few people were fully aware of the difficulties of conducting an Antarctic ice accumulation program. In fact, the only man of the present generation having made an extensive study of Antarctic firn (metamorphosed snow) was Valter Schytt of the Norwegian-British-Swedish Expedition, 1949-52. Quite probably he was the one man who realized just how bewildering interpretation of stratigraphy of a snow pit wall in Antarctica could be. [...]

Snow accumulation in mountain headwater basins is vitally important to southern Alberta, where snowmelt supplies more than 80% of annual downstream runoff. This study evaluated two snow measurement techniques, and snow accumulation in southwestern Alberta. The SnowHydro sampler was compared with existing designs and observed to perform better under the forest canopy. A total station was evaluated for remotely measuring snow depth in avalanche terrain, but found to have accuracy limitations in low snow accumulation conditions. Field data were combined with indices of snow accumulation drivers to run classification and regression tree analysis (C&RT). Results quantified controls on accumulation over two years, and created spatial distributions of snow water equivalent across the watershed. Elevation was the dominant control between years, while canopy closure, slope angle, and aspect varied in importance between years and within seasons. Accurate representations of SWE suggest that C&RT could improve annual provincial water supply forecasts. / xiii, 171 leaves ; 29 cm

No description available.

Instrumentation commonly used to measure snowpack stratigraphy, snow density, Snow Water Equivalent (SWE), temperature and liquid water content is usually invasive and requires disruption of the snowpack. Most measurement techniques modify the snow medium and more than one sample cannot be taken at the same location. This does not permit continuous monitoring of these parameters using a single measurement instrument. An acoustic wave sent into the snowpack was used to measure snow. To provide the theory required to make acoustic measurements, the Biot-Stoll model of sound wave propagation in porous media was modified using a mixture theory so that it was applicable to a multiphase porous medium. The combined model is called the Unified Thermoacoustic Model (UTAM) for snow. An acoustic measurement device, the System for the Acoustic Sensing of Snow (SAS2), was designed to send sound waves into snow and to receive the reflected sound waves using a loudspeaker and a microphone array. A stationary version of the SAS2 was deployed on a met station and a portable version of the SAS2 was placed on a roving ski-based platform. The systems were deployed at field sites in the Canadian Rocky Mountains, Alberta. The results showed that the SAS2 was able to measure snow density, temperature, and liquid water content and serve as a replacement technology for snowtube and snowpit measurements. Snow density was estimated more accurately by the SAS2 than from commonly-used snow tube techniques.