More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to det... more More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to determine the aerodynamic and thermal roughness len gths of glacier ice. The results proved to be extremely se nsitive to measurement height, which is difficult to define precisely on the hummocky terrain of a glacier. Therefore, aerodynamic roughness leng th s were estimated from the microtopography of the surface, yielding 2.46 mm for ice, and 5.5 mm for snow. Despite the indeterminate nature of the profile analysis, it did support the view that the thermal roughness length must decrease as the roughness Reynolds number increases, a relationship which has been modelled in the literature. Good agreement between bulk-transfer estimates and eddy-correlation measurements of fhe sensible heat-flux density on melting ice and snow was obtained by combining the aerodynamic roughness length with a suitable model for thermal roughness length.
This paper presents hydrometeorological, glaciological and geospatial data from the Peyto Glacier... more This paper presents hydrometeorological, glaciological and geospatial data from the Peyto Glacier Research Basin (PGRB) in the Canadian Rockies. Peyto Glacier has been of interest to glaciological and hydrological researchers since the 1960s, when it was chosen as one of five glacier basins in Canada for the study of mass and water balance during the International Hydrological Decade (IHD, 1965-1974). Intensive studies of the glacier and observations of the glacier mass balance continued after the IHD, when the initial seasonal meteorological stations were discontinued, then restarted as continuous stations in the late 1980s. The corresponding hydrometric observations were discontinued in 1977 and restarted in 2013. Datasets presented in this paper include high-resolution, co-registered digital elevation models (DEMs) derived from original air photos and lidar surveys; hourly off-glacier meteorological data recorded from 1987 to the present; precipitation data from the nearby Bow Summit weather station; and long-term hydrological and glaciological model forcing datasets derived from bias-corrected reanalysis products. These data are crucial for studying climate change and variability in the basin and understanding the hydrological responses of the basin to both glacier and climate change. The comprehensive dataset for the PGRB is a valuable and exceptionally long-standing testament to the impacts of climate change on the cryosphere in the high-mountain environment.
The influence of digital elevation model (DEM) resolution to modelled glacier melt during peak me... more The influence of digital elevation model (DEM) resolution to modelled glacier melt during peak melt production was evaluated by performing a clear sky GIS radiation simulation over the Peyto Glacier in the Canadian Rockies. DEMs were generated at eight resolutions ranging from 1 m to 1000 m grid spacing from airborne lidar data. When applied to the planar area (PA) of the terrain, it was found that total melt increased with DEM resolution (r 2 D 0Ð63) by 4% over 3 orders of magnitude. This systematic scaling-effect was mitigated at the basin scale, however, when the DEM slope variant area (SVA) was used to account for the increased divergence from PA as resolution increases. However, even after the inclusion of SVA in glacier surface melt simulations, localized melt variations with scale were still evident in the ablation and accumulation zone observations. In the ablation zone, there was a systematic increase in simulated melt (¾4%) as resolution decreased from 1 m to 1000 m (r 2 D 0Ð89), with the opposite effect in the accumulation zone (r 2 D 0Ð81). DEM resolution also affected the diurnal melt cycle, such that for the entire glacier there was a tendency for a morning over-estimation and afternoon underestimation of melt rate with decreasing resolution. For the accumulation zone, there was an increased melt rate at low resolutions occurring in the afternoon, while in the ablation zone there was a tendency for increasing melt rates with decreasing resolution throughout the day. These localized spatio-temporal variations in simulated melt are largely due to the lowering of ridges and raising of valley floors that occur as resolution decreases. This scale dependence in the representation of terrain morphology directly controls the pattern and relative proportion of direct beam shadowing over actively melting surfaces and thereby has a systematic influence on the grid cell-level hydrological balance. It is recommended that GIS-based glacier melt modelling routines take into account the slope area of grid cells, while noting that the choice of DEM scale can have a discernible and systematic influence on modelled runoff magnitude. It is important to note that while higher grid resolutions mitigate the effect of terrain smoothing on spatio-temporal melt patterns, lower resolutions actually mitigate the systematic error associated with assuming all surface areas are planar.
Glacier hydrological research in Canada from 2002-2007 continues to advance, driven by new observ... more Glacier hydrological research in Canada from 2002-2007 continues to advance, driven by new observations of glacier retreat in all regions of the country. New observation networks have been formed to study various aspects of glacier change and linkages with the hydrological system. Smallscale studies of accumulation and melt processes on glacier surfaces continue, and are being used to parameterize spatially distributed models of glacier mass balance and melt. Increasing emphasis has been placed on downscaling of regional and global climate model output to use as input to mass balance models. Advances in our understanding of water movement from the glacier surface to the bed has led to increased interest in runoff from glacierized catchments, which has significant policy implications for downstream water users. Continuing research includes maintenance and enhancement of field monitoring capabilities, improved algorithms to downscale climate model output, and adjustments to hydrological models to more accurately represent glacier cover for streamflow prediction.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to det... more More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to determine the aerodynamic and thermal roughness len gths of glacier ice. The results proved to be extremely se nsitive to measurement height, which is difficult to define precisely on the hummocky terrain of a glacier. Therefore, aerodynamic roughness leng th s were estimated from the microtopography of the surface, yielding 2.46 mm for ice, and 5.5 mm for snow. Despite the indeterminate nature of the profile analysis, it did support the view that the thermal roughness length must decrease as the roughness Reynolds number increases, a relationship which has been modelled in the literature. Good agreement between bulk-transfer estimates and eddy-correlation measurements of fhe sensible heat-flux density on melting ice and snow was obtained by combining the aerodynamic roughness length with a suitable model for thermal roughness length.
This paper documents the performance of the organic soil version of the Canadian Land Surface Sch... more This paper documents the performance of the organic soil version of the Canadian Land Surface Scheme (CLASS) in modelling the hydrology and energy balance of the Beverly Swamp, Southern Ontario. The hydrometeorological dataset used to assess model performance begins in the autumn of 1983 and spans 33 months, presenting the first multi-year characterization of the area. The Beverly Swamp receives approximately 900 mm of precipitation per year, of which one third is lost to net runoff, and the remainder to evaporation. Vertical drainage at this site is impeded, due to the presence of a marl layer below the highly decomposed peat soil, at approximately 1-m depth. This mixed-forest wetland is unique among surfaces used for CLASS testing to date. Within CLASS, vertical drainage at the bottom of the soil profile is set to zero to represent the marl subsurface boundary. Preliminary runs have shown that after each melt period this produced ponded water on site which persisted from year to year. The inclusion of a simple lateral drainage function in CLASS simulated actual measured lateral surface flow, and effectively reproduced seasonal differences in water table position. Comparisons between measured and modelled diurnally averaged energy budget components taken from two summers indicate that there is a marked tendency for CLASS to underestimate latent heat flux (Q E) by 29% of the observed values, the major cause of this disagreement being due to systematic error. Concurrent with this error is an overestimation of the magnitude of soil heat storage (Q G), by a factor of seven, wherein the error is dominantly systematic. Modifications made to the canopy resistance parametrization, based on site measurements, resulted in improved model estimates of Q E , reducing the underestimation to 12% of observed values, and changing the major cause of error from systematic to unsystematic in nature. The improvement in Q E corresponded with a change in the prediction of sensible heat flux (Q H). A tendency to overestimate Q H by 20% of the observed values changed to an underestimation of Q H by 14%, the error being unsystematic in each case. The modifications resulted in no significant change to either the magnitude or the nature of the error for Q G .
ABSTRACT. A scheme for katabatic turbulent heat transfer proposed by Oerlemans and Grisogono (200... more ABSTRACT. A scheme for katabatic turbulent heat transfer proposed by Oerlemans and Grisogono (2002), here referred to as the OG parameterization, is compared with bulk heat-transfer estimates on Peyto Glacier, Alberta, Canada. Automatic weather stations (AWSs) provide off-glacier ...
ABSTRACT. lodels for calculating glacier mass balance are sensitive to surface reflectivity varia... more ABSTRACT. lodels for calculating glacier mass balance are sensitive to surface reflectivity variation. Fieldwork carried out on Peyto Glacier, Alberta, Canada, contributes to the data set available for ice-reflecti\'ity parameterization in such models. H emispherical reflectivity in ...
Hydrology and Earth System Sciences Discussions, 2010
A micrometeorological experiment was conducted in the summer of 2008, at Peyto Glacier, during fo... more A micrometeorological experiment was conducted in the summer of 2008, at Peyto Glacier, during four meltwater production periods of 1, 3, 4 and 5 days duration, the last two days marked by late summer snow cover. The data include a breakdown of net radiation into its short-and long-wave components, as well as wind speed, temperature and humidity profile data for use in bulk transfer estimates of sensible heat and moisture transfer. In addition, a hydrological experiment was conducted, the data comprising sonic sounder measurements of ablation and stage level records of discharge from a supraglacial microbasin. As expected, the ratio of daily average runoff flow measurement to energy budget flow estimates is less than one on most days because of weathering crust development. Also, the conversion of stage level data into discharge from a supraglacial catchment presents challenges, notably defining the area of a loosely defined basin and specifying stage level on a downward moving surface. Nevertheless, it is clear that peak discharge lags peak meltwater energy input by periods of four to six hours. A suitably lagged flow estimate can be achieved by passing the flow through a simple storage reservoir, using delay times of 14.5, 15, 7.5 and 9 h for each respective measurement period. This suggests that a substantial part of the delay in runoff from a glacier basin is tied up in ice surface hydrological processes.
More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to det... more More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to determine the aerodynamic and thermal roughness len gths of glacier ice. The results proved to be extremely se nsitive to measurement height, which is difficult to define precisely on the hummocky terrain of a glacier. Therefore, aerodynamic roughness leng th s were estimated from the microtopography of the surface, yielding 2.46 mm for ice, and 5.5 mm for snow. Despite the indeterminate nature of the profile analysis, it did support the view that the thermal roughness length must decrease as the roughness Reynolds number increases, a relationship which has been modelled in the literature. Good agreement between bulk-transfer estimates and eddy-correlation measurements of fhe sensible heat-flux density on melting ice and snow was obtained by combining the aerodynamic roughness length with a suitable model for thermal roughness length.
This paper presents hydrometeorological, glaciological and geospatial data from the Peyto Glacier... more This paper presents hydrometeorological, glaciological and geospatial data from the Peyto Glacier Research Basin (PGRB) in the Canadian Rockies. Peyto Glacier has been of interest to glaciological and hydrological researchers since the 1960s, when it was chosen as one of five glacier basins in Canada for the study of mass and water balance during the International Hydrological Decade (IHD, 1965-1974). Intensive studies of the glacier and observations of the glacier mass balance continued after the IHD, when the initial seasonal meteorological stations were discontinued, then restarted as continuous stations in the late 1980s. The corresponding hydrometric observations were discontinued in 1977 and restarted in 2013. Datasets presented in this paper include high-resolution, co-registered digital elevation models (DEMs) derived from original air photos and lidar surveys; hourly off-glacier meteorological data recorded from 1987 to the present; precipitation data from the nearby Bow Summit weather station; and long-term hydrological and glaciological model forcing datasets derived from bias-corrected reanalysis products. These data are crucial for studying climate change and variability in the basin and understanding the hydrological responses of the basin to both glacier and climate change. The comprehensive dataset for the PGRB is a valuable and exceptionally long-standing testament to the impacts of climate change on the cryosphere in the high-mountain environment.
The influence of digital elevation model (DEM) resolution to modelled glacier melt during peak me... more The influence of digital elevation model (DEM) resolution to modelled glacier melt during peak melt production was evaluated by performing a clear sky GIS radiation simulation over the Peyto Glacier in the Canadian Rockies. DEMs were generated at eight resolutions ranging from 1 m to 1000 m grid spacing from airborne lidar data. When applied to the planar area (PA) of the terrain, it was found that total melt increased with DEM resolution (r 2 D 0Ð63) by 4% over 3 orders of magnitude. This systematic scaling-effect was mitigated at the basin scale, however, when the DEM slope variant area (SVA) was used to account for the increased divergence from PA as resolution increases. However, even after the inclusion of SVA in glacier surface melt simulations, localized melt variations with scale were still evident in the ablation and accumulation zone observations. In the ablation zone, there was a systematic increase in simulated melt (¾4%) as resolution decreased from 1 m to 1000 m (r 2 D 0Ð89), with the opposite effect in the accumulation zone (r 2 D 0Ð81). DEM resolution also affected the diurnal melt cycle, such that for the entire glacier there was a tendency for a morning over-estimation and afternoon underestimation of melt rate with decreasing resolution. For the accumulation zone, there was an increased melt rate at low resolutions occurring in the afternoon, while in the ablation zone there was a tendency for increasing melt rates with decreasing resolution throughout the day. These localized spatio-temporal variations in simulated melt are largely due to the lowering of ridges and raising of valley floors that occur as resolution decreases. This scale dependence in the representation of terrain morphology directly controls the pattern and relative proportion of direct beam shadowing over actively melting surfaces and thereby has a systematic influence on the grid cell-level hydrological balance. It is recommended that GIS-based glacier melt modelling routines take into account the slope area of grid cells, while noting that the choice of DEM scale can have a discernible and systematic influence on modelled runoff magnitude. It is important to note that while higher grid resolutions mitigate the effect of terrain smoothing on spatio-temporal melt patterns, lower resolutions actually mitigate the systematic error associated with assuming all surface areas are planar.
Glacier hydrological research in Canada from 2002-2007 continues to advance, driven by new observ... more Glacier hydrological research in Canada from 2002-2007 continues to advance, driven by new observations of glacier retreat in all regions of the country. New observation networks have been formed to study various aspects of glacier change and linkages with the hydrological system. Smallscale studies of accumulation and melt processes on glacier surfaces continue, and are being used to parameterize spatially distributed models of glacier mass balance and melt. Increasing emphasis has been placed on downscaling of regional and global climate model output to use as input to mass balance models. Advances in our understanding of water movement from the glacier surface to the bed has led to increased interest in runoff from glacierized catchments, which has significant policy implications for downstream water users. Continuing research includes maintenance and enhancement of field monitoring capabilities, improved algorithms to downscale climate model output, and adjustments to hydrological models to more accurately represent glacier cover for streamflow prediction.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to det... more More than lOO simultaneously measured profiles of wind speed and temperature were analyzed to determine the aerodynamic and thermal roughness len gths of glacier ice. The results proved to be extremely se nsitive to measurement height, which is difficult to define precisely on the hummocky terrain of a glacier. Therefore, aerodynamic roughness leng th s were estimated from the microtopography of the surface, yielding 2.46 mm for ice, and 5.5 mm for snow. Despite the indeterminate nature of the profile analysis, it did support the view that the thermal roughness length must decrease as the roughness Reynolds number increases, a relationship which has been modelled in the literature. Good agreement between bulk-transfer estimates and eddy-correlation measurements of fhe sensible heat-flux density on melting ice and snow was obtained by combining the aerodynamic roughness length with a suitable model for thermal roughness length.
This paper documents the performance of the organic soil version of the Canadian Land Surface Sch... more This paper documents the performance of the organic soil version of the Canadian Land Surface Scheme (CLASS) in modelling the hydrology and energy balance of the Beverly Swamp, Southern Ontario. The hydrometeorological dataset used to assess model performance begins in the autumn of 1983 and spans 33 months, presenting the first multi-year characterization of the area. The Beverly Swamp receives approximately 900 mm of precipitation per year, of which one third is lost to net runoff, and the remainder to evaporation. Vertical drainage at this site is impeded, due to the presence of a marl layer below the highly decomposed peat soil, at approximately 1-m depth. This mixed-forest wetland is unique among surfaces used for CLASS testing to date. Within CLASS, vertical drainage at the bottom of the soil profile is set to zero to represent the marl subsurface boundary. Preliminary runs have shown that after each melt period this produced ponded water on site which persisted from year to year. The inclusion of a simple lateral drainage function in CLASS simulated actual measured lateral surface flow, and effectively reproduced seasonal differences in water table position. Comparisons between measured and modelled diurnally averaged energy budget components taken from two summers indicate that there is a marked tendency for CLASS to underestimate latent heat flux (Q E) by 29% of the observed values, the major cause of this disagreement being due to systematic error. Concurrent with this error is an overestimation of the magnitude of soil heat storage (Q G), by a factor of seven, wherein the error is dominantly systematic. Modifications made to the canopy resistance parametrization, based on site measurements, resulted in improved model estimates of Q E , reducing the underestimation to 12% of observed values, and changing the major cause of error from systematic to unsystematic in nature. The improvement in Q E corresponded with a change in the prediction of sensible heat flux (Q H). A tendency to overestimate Q H by 20% of the observed values changed to an underestimation of Q H by 14%, the error being unsystematic in each case. The modifications resulted in no significant change to either the magnitude or the nature of the error for Q G .
ABSTRACT. A scheme for katabatic turbulent heat transfer proposed by Oerlemans and Grisogono (200... more ABSTRACT. A scheme for katabatic turbulent heat transfer proposed by Oerlemans and Grisogono (2002), here referred to as the OG parameterization, is compared with bulk heat-transfer estimates on Peyto Glacier, Alberta, Canada. Automatic weather stations (AWSs) provide off-glacier ...
ABSTRACT. lodels for calculating glacier mass balance are sensitive to surface reflectivity varia... more ABSTRACT. lodels for calculating glacier mass balance are sensitive to surface reflectivity variation. Fieldwork carried out on Peyto Glacier, Alberta, Canada, contributes to the data set available for ice-reflecti\'ity parameterization in such models. H emispherical reflectivity in ...
Hydrology and Earth System Sciences Discussions, 2010
A micrometeorological experiment was conducted in the summer of 2008, at Peyto Glacier, during fo... more A micrometeorological experiment was conducted in the summer of 2008, at Peyto Glacier, during four meltwater production periods of 1, 3, 4 and 5 days duration, the last two days marked by late summer snow cover. The data include a breakdown of net radiation into its short-and long-wave components, as well as wind speed, temperature and humidity profile data for use in bulk transfer estimates of sensible heat and moisture transfer. In addition, a hydrological experiment was conducted, the data comprising sonic sounder measurements of ablation and stage level records of discharge from a supraglacial microbasin. As expected, the ratio of daily average runoff flow measurement to energy budget flow estimates is less than one on most days because of weathering crust development. Also, the conversion of stage level data into discharge from a supraglacial catchment presents challenges, notably defining the area of a loosely defined basin and specifying stage level on a downward moving surface. Nevertheless, it is clear that peak discharge lags peak meltwater energy input by periods of four to six hours. A suitably lagged flow estimate can be achieved by passing the flow through a simple storage reservoir, using delay times of 14.5, 15, 7.5 and 9 h for each respective measurement period. This suggests that a substantial part of the delay in runoff from a glacier basin is tied up in ice surface hydrological processes.
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