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J W Pomeroy - One of the best experts on this subject based on the ideXlab platform.
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warm air entrainment and advection during alpine Blowing Snow events
The Cryosphere, 2020Co-Authors: Nikolas O. Aksamit, J W PomeroyAbstract:Abstract. Blowing Snow transport has considerable impact on the hydrological cycle in alpine regions both through the redistribution of the seasonal Snowpack and through sublimation back into the atmosphere. Alpine energy and mass balances are typically modeled with time-averaged approximations of sensible and latent heat fluxes. This oversimplifies nonstationary turbulent mixing in complex terrain and may overlook important exchange processes for hydrometeorological prediction. To determine if specific turbulent motions are responsible for warm- and dry-air advection during Blowing Snow events, quadrant analysis and variable interval time averaging was used to investigate turbulent time series from the Fortress Mountain Snow Laboratory alpine study site in the Canadian Rockies, Alberta, Canada, during the winter of 2015–2016. By analyzing wind velocity and sonic temperature time series with concurrent Blowing Snow, such turbulent motions were found to supply substantial sensible heat to near-surface wind flows. These motions were responsible for temperature fluctuations of up to 1 ∘ C, a considerable change for energy balance estimation. A simple scaling relationship was derived that related the frequency of dominant downdraft and updraft events to their duration and local variance. This allows for the first parameterization of entrained or advected energy for time-averaged representations of Blowing Snow sublimation and suggests that advection can strongly reduce thermodynamic feedbacks between Blowing Snow sublimation and the near-surface atmosphere. The downdraft and updraft scaling relationship described herein provides a significant step towards a more physically based Blowing Snow sublimation model with more realistic mixing of atmospheric heat. Additionally, calculations of return frequencies and event durations provide a field-measurement context for recent findings of nonstationarity impacts on sublimation rates.
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scale interactions in turbulence for mountain Blowing Snow
Journal of Hydrometeorology, 2017Co-Authors: Nikolas O. Aksamit, J W PomeroyAbstract:AbstractBlowing Snow particle transport responds to wind motions across many length and time scales. This coupling is nonlinear by nature and complicated in atmospheric flows where eddies of many sizes are superimposed. In mountainous terrain, wind flow descriptions are further complicated by topographically influenced or enhanced flows. To improve the current understanding and modeling of Blowing Snow transport in complex terrain, statistically significant timing and frequencies of wind–Snow coupling were identified in high-frequency observations of surface Blowing Snow and near-surface turbulence from a mountain field site in the Canadian Rockies. Investigation of the mechanisms influencing near-surface, high-frequency turbulence and Snow concentration fluctuations provided strong evidence for amplitude modulation from large-scale motions. The large-scale atmospheric motions modulating near-surface turbulence and Snow transport were then compared to specific quadrant analysis structures recently identif...
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near surface Snow particle dynamics from particle tracking velocimetry and turbulence measurements during alpine Blowing Snow storms
The Cryosphere, 2016Co-Authors: Nikolas O. Aksamit, J W PomeroyAbstract:Abstract. Many Blowing Snow conceptual and predictive models have been based on simplified two-phase flow dynamics derived from time-averaged observations of bulk flow conditions in Blowing Snow storms. Measurements from the first outdoor application of particle tracking velocimetry (PTV) of near-surface Blowing Snow yield new information on mechanisms for Blowing Snow initiation, entrainment, and rebound, whilst also confirming some findings from wind tunnel observations. Blowing Snow particle movement is influenced by complex surface flow dynamics, including saltation development from creep that has not previously been measured for Snow. Comparisons with 3-D atmospheric turbulence measurements show that Blowing Snow particle motion immediately above the Snow surface responds strongly to high-frequency turbulent motions. Momentum exchange from wind to the dense near-surface particle-laden flow appears significant and makes an important contribution to Blowing Snow mass flux and saltation initiation dynamics. The more complete and accurate description of near-surface Snow particle motions observable using PTV may prove useful for improving Blowing Snow model realism and accuracy.
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a triple moment Blowing Snow atmospheric model and its application in computing the seasonal wintertime Snow mass budget
Hydrology and Earth System Sciences, 2010Co-Authors: J Yang, Xing Fang, Man K Yau, J W PomeroyAbstract:Abstract. Many field studies have shown that surface sublimation and Blowing Snow transport and sublimation have significant influences on the Snow mass budget in many high latitude regions. We developed a coupled triple-moment Blowing Snow-atmospheric modeling system to study the influence of these processes on a seasonal time scale over the Northern Hemisphere. Two simulations were performed. The first is a 5 month simulation for comparison with Snow survey measurements over a Saskatchewan site to validate the modeling system. The second simulation covers the 2006/2007 winter period to study the Snow mass budget over the Northern Hemisphere. The results show that surface sublimation is significant in Eurasian Continent and the eastern region of North America, reaching a maximum value of 200 mm SWE (Snow Water Equivalent). Over the Arctic Ocean and Northern Canada, surface deposition with an average value of 30 mm SWE was simulated. Blowing Snow sublimation was found to return up to 50 mm SWE back to the atmosphere over the Arctic Ocean, while the divergence of Blowing Snow transport contributes only a few mm SWE to the change in Snow mass budget. The results were further stratified in 10 degree latitudinal bands. The results show that surface sublimation decreases with an increase in latitude while Blowing Snow sublimation increases with latitude. Taken together, the surface sublimation and Blowing Snow processes was found to distribute 23% to 52% of winter precipitation over the three month winter season.
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modelling Blowing Snow redistribution to prairie wetlands
Hydrological Processes, 2009Co-Authors: Xing Fang, J W PomeroyAbstract:Blowing Snow transports and sublimates a substantial portion of the seasonal Snowfall in the prairies of western Canada. Snow redistribution is an important feature of prairie hydrology as deep Snowdrifts provide a source of meltwater to replenish ponds and generate streamflow in this dry region. The spatial distribution of Snow water equivalent in the spring is therefore of great interest. A test of the distributed and aggregated modelling strategies for Blowing Snow transport and sublimation was conducted at the St. Denis National Wildlife Area in the rolling, internally drained prairie pothole region east of Saskatoon, Saskatchewan, Canada. A LiDAR-based DEM and aerial photograph-based vegetation cover map were available for this region. A coupled complex windflow and Blowing Snow model was run with 262,1446 m x 6 m grid cells to produce spatially distributed estimates of seasonal Blowing Snow transport and sublimation. The calculation was then aggregated to seven landscape units that represented the major influences of surface roughness, topography and fetch on Blowing Snow transport and sublimation. Both the distributed and aggregated simulations predicted similar end-of-winter Snow water equivalent with substantial redistribution of Blowing Snow from exposed sparsely vegetated sites across topographic drainage divides to the densely vegetated pothole wetlands. Both simulations also agreed well with Snow survey observations. While the distributed calculations provide a fascinating and detailed visual image of the interaction of complex landscapes and Blowing Snow redistribution and sublimation, it is clear that Blowing Snow transport and sublimation calculations can be successfully aggregated to the spatial scale of the major landscape units in this environment. This means that meso and macroscale hydrological models can represent Blowing Snow redistribution successfully in the prairies.
M K Yau - One of the best experts on this subject based on the ideXlab platform.
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a case study of Blowing Snow cooling effects on anticyclogenesis and cyclolysis
Journal of Geophysical Research, 2011Co-Authors: Jing Yang, M K YauAbstract:[1] This paper focuses on Blowing Snow and its effect, through thermodynamic forcing, on anticyclogenesis and cyclolysis. A triple-moment Blowing Snow model (PIEKTUK-T) is coupled to an atmospheric model (MC2), and this system is used to simulate an anticyclogenesis event. For comparison, an uncoupled version of MC2 is used to model the same event. The coupled model (CPL) showed colder low-level temperatures in regions where Blowing Snow occurred. This cooling contributes to a rise in sea level pressure relative to the uncoupled simulation. A potential vorticity (PV) diagnostic is then applied to quantify how this microphysical cooling affects the geopotential height and balanced wind fields. Surface potential temperature differences between the coupled and uncoupled runs were used as lower boundary conditions for the inversion. The results showed that Blowing Snow has only a small cooling effect over the anticyclogenesis region in CPL and moderate cooling over Baffin Island, where a decaying cyclone was moving northward. The cooling induces positive geopotential height and anticyclonic flow perturbations extending up to 500 mbar over the cyclone region. The averaged inverted geopotential height anomaly at 1000 mbar level over the cooling region is up to 4.6 dam in 72 h. Surface cooling is demonstrated to play a role in the cyclolysis. The CPL run allows the relative humidity with respect to ice in the Blowing Snow module to remain supersaturated and includes the heat release from the supersaturated water vapor deposition. Another experiment was carried out, in which supersaturated vapor was not allowed in the Blowing Snow module. The sensitivity experiment results indicated that Blowing Snow cooling effects over Baffin Island will be much reduced.
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Recent Studies on the Climatology and Modeling of Blowing Snow in the Mackenzie River Basin
Cold Region Atmospheric and Hydrologic Studies. The Mackenzie GEWEX Experience, 2008Co-Authors: Stephen J Dery, M K YauAbstract:This chapter presents a multi-scale analysis of the contribution of Blowing Snow to the hydrometeorology of the Mackenzie River Basin (MRB). A climatology of adverse wintertime weather events demonstrates that Blowing Snow events are rare within the forested sections of the MRB but become more frequent in the northern parts of the Basin covered by tundra, which experience the largest impacts of Blowing Snow transport and sublimation due to large-scale processes. A parameterization for Blowing Snow sublimation based on the PIEKTUK-D model and the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA-15) data is used to determine that the combined processes of surface and Blowing Snow sublimation deplete 29 mm yr-1 Snow water equivalent, or about 7% of the watershed’s annual precipitation. This study provides only a first-order estimate of the contribution of surface sublimation and Blowing Snow to the MRB surface mass balance because of limitations with the dataset and some uncertainties in the Blowing Snow process.
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a new triple moment Blowing Snow model
Boundary-Layer Meteorology, 2007Co-Authors: Jing Yang, M K YauAbstract:This paper presents a new triple-moment Blowing Snow model PIEKTUK-T by including predictive equations for three moments of the gamma size distribution. Specifically, predictive equations for the total number concentration, total mass mixing ratio, and total radar reflectivity for Blowing Snow are included. Tests in the context of idealized experiments and observed case studies demonstrate that the triple-moment model performs better than the double-moment model PIEKTUK-D in predicting the evolution of the number concentration, mixing ratio, shape parameter, and visibility in Blowing Snow, provided that the fall velocities for the total number concentration, mass mixing ratio, and radar reflectivity are weighted by the same order of the respective moments in both models. The power law relationship between the radar reflectivity factor and particle extinction coefficient found in PIEKTUK-T is consistent with one observed in Snow storms. Coupling of the triple-moment Blowing Snow model to an atmospheric model would allow realistic studies of the effect of Blowing Snow on weather and climate.
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large scale mass balance effects of Blowing Snow and surface sublimation
Journal of Geophysical Research, 2002Co-Authors: Stephen J Dery, M K YauAbstract:[1] This study examines the effects of surface sublimation and Blowing Snow on the surface mass balance on a global and basin scale using the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA15) data at a resolution of 2.5° that span the years 1979–1993. The combined processes of surface and Blowing Snow sublimation are estimated to remove 29 mm yr−1 Snow-water equivalent (swe) over Antarctica, disposing about 17 to 20% of its annual precipitation. In the Northern Hemisphere, these processes are generally less important in continental areas than over the frozen Arctic Ocean, where surface and Blowing Snow sublimation deplete upward of 100 mm yr−1 swe. Areas with frequent Blowing Snow episodes, such as the coastal regions of Antarctica and the Arctic Ocean, are prone to a mass transport >100 Mg m−1 yr−1. Although important locally, values of the divergence of mass through wind redistribution are generally 2 orders of magnitude less than surface and Blowing Snow sublimation when evaluated over large areas. For the entire Mackenzie River Basin of Canada, surface sublimation remains the dominant sink of mass as it removes 29 mm yr−1 swe, or about 7% of the watershed's annual precipitation. Although the first of its kind, this study provides only a first-order estimate of the contribution of surface sublimation and Blowing Snow to the surface mass balance because of limitations with the data set and some uncertainties in the Blowing Snow process.
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simulation of an arctic ground blizzard using a coupled Blowing Snow atmosphere model
Journal of Hydrometeorology, 2001Co-Authors: Stephen J Dery, M K YauAbstract:A ground blizzard occurred from 16 to 18 November 1996 in the northern sectors of the Mackenzie River basin of Canada and the adjacent Beaufort Sea. This hazardous event, accompanied by a low-level jet with wind speeds approaching 20 m s21 and extensive Blowing Snow near the surface (but clear sky aloft), is forced by a strong sea level pressure gradient that forms between a rapidly intensifying anticyclone over the Nunavut and Northwest Territories of Canada and an intense depression over the frozen Arctic Ocean. The event is first simulated at a horizontal grid size of 18 km using the uncoupled Canadian Mesoscale Compressible Community (MC2) model. This experiment is shown to capture the rapid anticyclogenesis event within 2 hPa of its central sea level pressure and the blizzard conditions near the Canadian Arctic coastline and the Beaufort Sea. Meteorological conditions observed at Trail Valley Creek (TVC), a small Arctic tundra watershed in which ground blizzard conditions were experienced during the event, are also accurately reproduced by the uncoupled simulation with the notable exception of the Blowing Snow process. Thus, the mesoscale model is then coupled to the ‘‘PIEKTUK’’ Blowing Snow model, and a second simulation is conducted. This additional experiment reveals the presence of extensive Blowing Snow associated with a strong low-level jet over TVC and the adjacent frozen Beaufort Sea. Over the 2-day event, Blowing Snow sublimation and transport combined to erode 1.6 mm Snow water equivalent from the surface mass balance of TVC. The concurrent moistening and cooling of near-surface air due to Blowing Snow sublimation emerge during the blizzard but to a lesser extent than in an idealized modeling framework, as a consequence of entrainment and advective processes. Therefore, Blowing Snow sublimation rates are evaluated to be 1.8 times larger than in the stand-alone application of the PIEKTUK model to the same data.
Vincent Vionnet - One of the best experts on this subject based on the ideXlab platform.
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a meteorological and Blowing Snow data set 2000 2016 from a high elevation alpine site col du lac blanc france 2720 m a s l
Earth System Science Data, 2019Co-Authors: Gilbert Guyomarch, Kouichi Nishimura, Yannick Deliot, Firmin Fontaine, Philippe Puglièse, Vincent Vionnet, Hervé Bellot, Florence Naaimbouvet, Yves DurandAbstract:Abstract. A meteorological and Blowing Snow data set from the high-elevation experimental site of Col du Lac Blanc (2720 m a.s.l., Grandes Rousses mountain range, French Alps) is presented and detailed in this paper. Emphasis is placed on data relevant to the observations and modelling of wind-induced Snow transport in alpine terrain. This process strongly influences the spatial distribution of Snow cover in mountainous terrain with consequences for Snowpack, hydrological and avalanche hazard forecasting. In situ data consist of wind (speed and direction), Snow depth and air temperature measurements (recorded at four automatic weather stations), a database of Blowing Snow occurrence and measurements of Blowing Snow fluxes obtained from a vertical profile of Snow particle counters (2010–2016). Observations span the period from 1 December to 31 March for each winter season from 2000–2001 to 2015–2016. The time resolution has varied from 15 min until 2014 to 10 min for the last years. Atmospheric data from the meteorological reanalysis are also provided from 1 August 2000 to 1 August 2016. A digital elevation model (DEM) of the study area (1.5 km 2 ) at 1 m resolution is also provided in RGF 93 Lambert 93 coordinates. This data set has been used in the past to develop and evaluate physical parameterizations and numerical models of Blowing and drifting Snow in alpine terrain. Col du Lac Blanc is also a target site to evaluate meteorological and climate models in alpine terrain. It belongs to the CRYOBS-CLIM observatory (the CRYosphere, an OBServatory of the CLIMate), which is a part of the national research infrastructure OZCAR (Critical Zone Observatories – Application and Research) and have been a Global Cryospheric Watch Cryonet site since 2017. The data are available from the repository of the OSUG data centre https://doi.org/10.17178/CRYOBSCLIM.CLB.all .
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A meteorological and Blowing Snow data set (2000–2016) from a high-elevation alpine site (Col du Lac Blanc, France, 2720 m a.s.l.)
Earth System Science Data, 2019Co-Authors: Gilbert Guyomarc'h, Herv� Bellot, Kouichi Nishimura, Yannick Deliot, Yves Durand, Firmin Fontaine, Philippe Puglièse, Florence Naaim-bouvet, Vincent Vionnet, Mohamed NaaimAbstract:A meteorological and Blowing Snow data set from the high-elevation experimental site of Col du Lac Blanc (2720 m a.s.l., Grandes Rousses mountain range, French Alps) is presented and detailed in this paper. Emphasis is placed on data relevant to the observations and modelling of wind-induced Snow transport in alpine terrain. This process strongly influences the spatial distribution of Snow cover in mountainous terrain with consequences for Snowpack, hydrological and avalanche hazard forecasting. In situ data consist of wind (speed and direction), Snow depth and air temperature measurements (recorded at four automatic weather stations), a database of Blowing Snow occurrence and measurements of Blowing Snow fluxes obtained from a vertical profile of Snow particle counters (2010–2016). Observations span the period from 1 December to 31 March for each winter season from 2000–2001 to 2015–2016. The time resolution has varied from 15 min until 2014 to 10 min for the last years. Atmospheric data from the meteorological reanalysis are also provided from 1 August 2000 to 1 August 2016. A digital elevation model (DEM) of the study area (1.5 km2) at 1 m resolution is also provided in RGF 93 Lambert 93 coordinates. This data set has been used in the past to develop and evaluate physical parameterizations and numerical models of Blowing and drifting Snow in alpine terrain. Col du Lac Blanc is also a target site to evaluate meteorological and climate models in alpine terrain. It belongs to the CRYOBS-CLIM observatory (the CRYosphere, an OBServatory of the CLIMate), which is a part of the national research infrastructure OZCAR (Critical Zone Observatories – Application and Research) and have been a Global Cryospheric Watch Cryonet site since 2017. The data are available from the repository of the OSUG data centre https://doi.org/10.17178/CRYOBSCLIM.CLB.all.
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Blowing Snow experimental test site Col du Lac Blanc (French Alps) : past and on-going researches
2018Co-Authors: Florence Naaim-bouvet, Herv� Bellot, Kouichi Nishimura, Yannick Deliot, Gilbert Guyomarc’h, Vincent Vionnet, Arnaud Laurent, Yoichi Ito, Ghislain Picard, Peter SchonAbstract:The Col du Lac Blanc (French Alps, 2720 m a.s.l., Apes d’Huez ski resort) has been since 1990 a shared research field site dedicated to observation and modelling studies on wind-induced Snow transport operated by Snow Research Centre (Centre d’Etudes de la Neige, Centre National de Recherches Météorologiques, Météo-France – CNRS) and the ETNA unit (IRSTEA, Univ. Grenoble Alpes) It is now a part of research Infrastructure OZCAR which is dedicated to Critical Zone study. Its specific toporaphy (pass) allows about 90% of wind conditions to be channelized in the N-S direction, thus acting as a natural wind tunnel. The site is equipped with a dedicated, permanent instrumentation focused on wind and Snow transport, standard meteorological observations and more recently, radiations. Meteorological data are shared (Guyomarc’h et al., 2018) (http://doi.osug.fr/public/CRYOBSCLIM_CLB/index.html.) Recent studies have focused on intercomparison of Blowing Snow sensors (Cierco et al., 2007; Trouvilliez et al., 2015), fine scale processes during Blowing Snow events (Naaim-Bouvet et al., 2010, 2011, 2013; Nishimura et al., 2014) and the development and evaluation of Blowing Snow models (Durand et al., 2005; Vionnet et al., 2013, 2014, 2017), including Blowing Snow scheme which have been implemented in a system for avalanche hazard forecasting (Vionnet et al., 2018). Classical terrestrial laserscans have also been performed at least twice each Snow season since 2010, enabling the study of Snow erosion/deposition pattern and the validation of numerical models. It also allows to improve a terrain-based parameter for the assessment of Snow depths in combination with Blowing Snow fluxes measurements (Schön et al., 2015, 2018). An automatic Rugged Laser Scan (RLS) covering daily a surface area of 200 m2 was also set up with the aim of understanding the link between Snow surface roughness, aerodynamic roughness and Snow mass fluxes. Detailed measurements of temperature and humidity in combination with measurements of Blowing Snow fluxes allowed the study of Blowing Snow sublimation and its feedbacks on the surface boundary layer. We will present a brief overview of the site's instrumentation and ongoing research related to Snow transport in the context of avalanche forecasting.
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Merging a terrain-based parameter with Blowing Snow fluxes for assessing Snow redistribution in alpine terrain
Cold Regions Science and Technology, 2018Co-Authors: Peter Schon, Florence Naaim-bouvet, Alexander Prokop, Vincent VionnetAbstract:Wind and the associated Snow transport are dominating factors determining the Snow distribution and accumulation in alpine areas. These factors result in a high spatial variability of Snow heights that is difficult to quantify. In this study, we propose an efficient method for estimations of changes in Snow heights during Blowing Snow events. We merge a terrain-based parameter Sx, which characterizes the degree of shelter or exposure of a point provided by the upwind terrain, with estimations of quantity of Snow transported by the wind. This estimation is provided by Snow particle counters (SPC) that estimate the Snow flux, the mass of drifting Snow particles per time and area. A modified terrain-based parameter Sxm is then used to distribute Snow over the terrain. The results are compared with measured changes in Snow heights resulting from Blowing Snow events, obtained with terrestrial laser scanning (TLS). Data and results are from the Col du Lac Blanc research site in the French Alps. We use a high raster resolution of 1 m, which is required when assessing the Snow-redistribution situation in highly structured terrain or in the starting zones of small and medium-sized avalanches. Results show that the proposed method can estimate Snow distributions based on a modified terrain parameter Sxm and measured Snow flux data. It can reproduce patterns of Snow redistribution and estimate changes in Snow heights reasonably well, as shown by correlation coefficients (R) of 0.78 to 0.86. The derivation of the modified terrain parameter Sxm and Snow flux are specific to the research site and not yet generally applicable. The formulations require the calibration and alteration of two parameters only for use in studies with other terrain and weather characteristics
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Operational implementation and evaluation of a Blowing Snow scheme for avalanche hazard forecasting
Cold Regions Science and Technology, 2018Co-Authors: Vincent Vionnet, Gérald Giraud, Gilbert Guyomarc’h, Matthieu Lafaysse, Florence Naaim-bouvet, Yannick DeliotAbstract:In alpine terrain, Blowing Snow events strongly affect the local evolution of the avalanche danger and must be taken into account by avalanche hazard forecasters. This study presents the implementation and the evaluation of the Blowing Snow scheme Sytron into the operational chain for avalanche hazard forecasting (named S2M) used in the main French mountain ranges. S2M-Sytron provides information on Blowing Snow occurrence and intensity per 300-m elevation bands and aspects for several regions of the French mountains. The wind forcing is provided by the meteorological analysis system SAFRAN. S2M-Sytron was evaluated for winter 2015/16 at 11 automatic stations measuring wind speed and Blowing Snow fluxes in the French Alps. The system detects 55% of Blowing Snow days with less than 10% of false alarms. S2M-Sytron captures the occurrence of Blowing Snow events with and without concurrent Snowfall. Improvements are obtained when considering an updated parameterization for the properties of falling Snow which reduces the threshold velocity for freshly fallen Snow. Using observed wind speed instead of SAFRAN wind speed to drive Sytron shows further improvements at stations where SAFRAN wind speed differs from the observations due to local topographic features. Overall, S2M-Sytron provides a regional Blowing Snow assessment but cannot fully reproduce the local intensity of Blowing Snow events.
Jing Yang - One of the best experts on this subject based on the ideXlab platform.
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a case study of Blowing Snow cooling effects on anticyclogenesis and cyclolysis
Journal of Geophysical Research, 2011Co-Authors: Jing Yang, M K YauAbstract:[1] This paper focuses on Blowing Snow and its effect, through thermodynamic forcing, on anticyclogenesis and cyclolysis. A triple-moment Blowing Snow model (PIEKTUK-T) is coupled to an atmospheric model (MC2), and this system is used to simulate an anticyclogenesis event. For comparison, an uncoupled version of MC2 is used to model the same event. The coupled model (CPL) showed colder low-level temperatures in regions where Blowing Snow occurred. This cooling contributes to a rise in sea level pressure relative to the uncoupled simulation. A potential vorticity (PV) diagnostic is then applied to quantify how this microphysical cooling affects the geopotential height and balanced wind fields. Surface potential temperature differences between the coupled and uncoupled runs were used as lower boundary conditions for the inversion. The results showed that Blowing Snow has only a small cooling effect over the anticyclogenesis region in CPL and moderate cooling over Baffin Island, where a decaying cyclone was moving northward. The cooling induces positive geopotential height and anticyclonic flow perturbations extending up to 500 mbar over the cyclone region. The averaged inverted geopotential height anomaly at 1000 mbar level over the cooling region is up to 4.6 dam in 72 h. Surface cooling is demonstrated to play a role in the cyclolysis. The CPL run allows the relative humidity with respect to ice in the Blowing Snow module to remain supersaturated and includes the heat release from the supersaturated water vapor deposition. Another experiment was carried out, in which supersaturated vapor was not allowed in the Blowing Snow module. The sensitivity experiment results indicated that Blowing Snow cooling effects over Baffin Island will be much reduced.
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A New Triple-Moment Blowing Snow Model
Boundary-Layer Meteorology, 2008Co-Authors: Jing YangAbstract:This paper presents a new triple-moment Blowing Snow model PIEKTUK-T by including predictive equations for three moments of the gamma size distribution. Specifically, predictive equations for the total number concentration, total mass mixing ratio, and total radar reflectivity for Blowing Snow are included. Tests in the context of idealized experiments and observed case studies demonstrate that the triple-moment model performs better than the double-moment model PIEKTUK-D in predicting the evolution of the number concentration, mixing ratio, shape parameter, and visibility in Blowing Snow, provided that the fall velocities for the total number concentration, mass mixing ratio, and radar reflectivity are weighted by the same order of the respective moments in both models. The power law relationship between the radar reflectivity factor and particle extinction coefficient found in PIEKTUK-T is consistent with one observed in Snow storms. Coupling of the triple-moment Blowing Snow model to an atmospheric model would allow realistic studies of the effect of Blowing Snow on weather and climate.
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a new triple moment Blowing Snow model
Boundary-Layer Meteorology, 2007Co-Authors: Jing Yang, M K YauAbstract:This paper presents a new triple-moment Blowing Snow model PIEKTUK-T by including predictive equations for three moments of the gamma size distribution. Specifically, predictive equations for the total number concentration, total mass mixing ratio, and total radar reflectivity for Blowing Snow are included. Tests in the context of idealized experiments and observed case studies demonstrate that the triple-moment model performs better than the double-moment model PIEKTUK-D in predicting the evolution of the number concentration, mixing ratio, shape parameter, and visibility in Blowing Snow, provided that the fall velocities for the total number concentration, mass mixing ratio, and radar reflectivity are weighted by the same order of the respective moments in both models. The power law relationship between the radar reflectivity factor and particle extinction coefficient found in PIEKTUK-T is consistent with one observed in Snow storms. Coupling of the triple-moment Blowing Snow model to an atmospheric model would allow realistic studies of the effect of Blowing Snow on weather and climate.
Stephen P Palm - One of the best experts on this subject based on the ideXlab platform.
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importance of Blowing Snow during cloudy conditions in east antarctica comparison of ground based and space borne retrievals over ice shelf and mountain regions
Frontiers in Earth Science, 2020Co-Authors: Alexandra Gossart, Stephen P Palm, Niels Souverijns, Irina Gorodetskaya, Stef Lhermitte, Jan T M Lenaerts, Nicole Van LipzigAbstract:Continuous measurements of Blowing Snow are scarce, both in time and space. Satellites now provide the opportunity to derive Blowing Snow occurrences, transport and sublimation rates over Antarctica. These products are extremely valuable and offer a continental-wide assessment of Blowing Snow, which is an important but unknown component of the surface mass balance of the Antarctic ice sheet. However, little ground truth is available to validate these retrievals. The recent application of ceilometers for detection of Blowing Snow frequencies provides an opportunity to validate the satellite retrievals of Blowing Snow frequencies at the Princess Elisabeth and Neumayer stations, East Antarctica for the 2011-2016 time period. A routine to detect Blowing Snow occurrence from remote sensing ceilometers has been developed at those locations. Thanks to their ground-based location, ceilometers are able to detect Blowing Snow events in the presence of clouds and precipitation, which can be missed by the satellite, since optically thick clouds impede the penetration of the signal. This is important, since the proportion of events missed by the CALIPSO and ICESat-2 satellites due to the presence of cloud decks is currently unknown. Over coastal areas, up to 90% of Blowing Snow happens under cloudy conditions and represent 30%of all cloudy conditions at both Neumayer and Princess Elisabeth stations. Although both detection methods have their limitations, 10% (4%) of the measurements at Princess Elisabeth (and Neumayer) are identified as Blowing Snow by the satellite but not by the ceilometer, likely due to differences in sensors, limitation of the surface identification by the satellite, or the spatial inhomogeneity of the Blowing Snow event. While the satellite Blowing Snow retrieval is a useful product, further investigation is needed to reduce the uncertainties on Blowing Snow frequencies associated with clouds.
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Blowing Snow in east antarctica comparison of ground based and space borne retrievals
The Cryosphere Discussions, 2019Co-Authors: Alexandra Gossart, Stephen P Palm, Niels Souverijns, Irina Gorodetskaya, Stef Lhermitte, Jan T M Lenaerts, Nicole Van LipzigAbstract:Abstract. Continuous measurements of Blowing Snow are scarce, both in time and space. Satellites now provide the opportunity to derive Blowing Snow occurrences, transport and sublimation rates over Antarctica. However, little ground truth is available to validate these retrievals. The recent application of ceilometers for detection of Blowing Snow frequencies provides an opportunity to validate the satellite retrievals of Blowing Snow frequencies at the Princess Elisabeth and Neumayer stations, East Antarctica for the 2011–2016 time period. A routine to detect Blowing Snow occurrence from remote sensing ceilometers has been developed at those locations. Thanks to their ground-based location, ceilometers are able to detect Blowing Snow events in the presence of clouds and precipitation, which can be missed by the satellite, since optically thick clouds impede the penetration of the signal. This is important, since a 90 % of Blowing Snow happens under cloudy conditions at Neumayer and Princess Elisabeth station and represent 30 % of all cloudy conditions at both stations. Although both detection methods have their limitations, 10 % (4 %) of the measurements at Princess Elisabeth (and Neumayer) are identified as Blowing Snow by the satellite but not by the ceilometer, likely due to differences in sensors, limitation of the surface identification by the satellite, or the spatial inhomogeneity of the Blowing Snow event. While the satellite Blowing Snow retrieval is a useful product, further investigation is needed to reduce the uncertainties on Blowing Snow frequencies associated with clouds.
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insight into the thermodynamic structure of Blowing Snow layers in antarctica from dropsonde and calipso measurements
Journal of Applied Meteorology and Climatology, 2018Co-Authors: Stephen P Palm, Yuekui Yang, Vinay Kayetha, Julien P NicolasAbstract:AbstractBlowing Snow is a frequent and widespread phenomenon over most of Antarctica. The transport and sublimation of Blowing Snow are important for the mass balance of the Antarctic ice sheet, an...
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link between arctic tropospheric bro explosion observed from space and sea salt aerosols from Blowing Snow investigated using ozone monitoring instrument bro data and geos 5 data assimilation system
Journal of Geophysical Research, 2018Co-Authors: S Choi, Stephen P Palm, Nicolas Theys, R J Salawitch, Pamela Wales, J Joiner, T Canty, K Chance, R M Suleiman, Richard I CullatherAbstract:Bromine radicals (Br + BrO) are important atmospheric species owing to their ability to catalytically destroy ozone as well as their potential impacts on the oxidative pathways of many trace gases, including dimethylsulfide and mercury. Using space‐based observations of BrO, recent studies have reported rapid enhancements of tropospheric BrO over large areas (so called “BrO explosions”) connected to near‐surface ozone depletion occurring in polar spring. However, the source(s) of reactive bromine and mechanism(s) that initiate these BrO explosions are uncertain. In this study, we investigate the relationships between Arctic BrO explosions and two of the proposed sources of reactive bromine: sea‐salt aerosol (SSA) generated from Blowing Snow and first‐year (seasonal) sea ice. We use tropospheric column BrO derived from the Ozone Monitoring Instrument (OMI) in conjunction with the Goddard Earth Observing System Version 5 (GEOS‐5) data assimilation system provided by National Aeronautics and Space Administration Global Modeling and Assimilation Office. Case studies demonstrate a strong association between the temporal and spatial extent of OMI‐observed BrO explosions and the GEOS‐5 simulated Blowing Snow‐generated SSA during Arctic spring. Furthermore, the frequency of BrO explosion events observed over the 11‐year record of OMI exhibits significant correlation with a time series of the simulated SSA emission flux in the Arctic and little to no correlation with a time series of satellite‐based first‐year sea ice area. Therefore, we conclude that SSA generated by Blowing Snow is an important factor in the formation of the BrO explosion observed from space during Arctic spring.
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link between arctic tropospheric bro explosion observed from space and sea salt aerosols from Blowing Snow investigated using ozone monitoring instrument bro data and geos 5 data assimilation system
Journal of Geophysical Research, 2018Co-Authors: Sungyeon Choi, Stephen P Palm, Nicolas Theys, R J Salawitch, Pamela Wales, J Joiner, T Canty, K Chance, R M Suleiman, Richard I CullatherAbstract:Bromine radicals (Br + BrO) are important atmospheric species owing to their ability to catalytically destroy ozone as well as their potential impacts on the oxidative pathways of many trace gases, including dimethylsulfide and mercury. Using space‐based observations of BrO, recent studies have reported rapid enhancements of tropospheric BrO over large areas (so called “BrO explosions”) connected to near‐surface ozone depletion occurring in polar spring. However, the source(s) of reactive bromine and mechanism(s) that initiate these BrO explosions are uncertain. In this study, we investigate the relationships between Arctic BrO explosions and two of the proposed sources of reactive bromine: sea‐salt aerosol (SSA) generated from Blowing Snow and first‐year (seasonal) sea ice. We use tropospheric column BrO derived from the Ozone Monitoring Instrument (OMI) in conjunction with the Goddard Earth Observing System Version 5 (GEOS‐5) data assimilation system provided by National Aeronautics and Space Administration Global Modeling and Assimilation Office. Case studies demonstrate a strong association between the temporal and spatial extent of OMI‐observed BrO explosions and the GEOS‐5 simulated Blowing Snow‐generated SSA during Arctic spring. Furthermore, the frequency of BrO explosion events observed over the 11‐year record of OMI exhibits significant correlation with a time series of the simulated SSA emission flux in the Arctic and little to no correlation with a time series of satellite‐based first‐year sea ice area. Therefore, we conclude that SSA generated by Blowing Snow is an important factor in the formation of the BrO explosion observed from space during Arctic spring.