Ski Loading and Flexure on a Groomed Snow Surface

Detection limits of analyzing instruments are the main reason for censored observations of pollutant concentrations. An iterative least squares method for regression analyses is developed to suit the doubly censored data commonly observed in environmental engineering. The modified iterative least squares method utilizes the expected values of censored observations estimated from the probability density function of doubly censored data in a regression process. The modified method is examined for bias in the estimation of the parameters of a linear model, and in the estimation of the standard deviation of the regression. A mechanistic model for atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) to a snow surface is formulated by utilizing the long-term PAH retention property of deep snowpacks. The modified iterative least squares method is applied to estimate the deposition parameters (dry deposition velocity and washout ratio) for various PAH species, since some of the PAH deposition levels were below the minimum detection limit of the analyzing instrument. The estimated parameters are examined statistically, and compare favourably with previously reported estimates of these parameters. Key words: censored data, regression, iterative least squares, PAHs, dry deposition velocity, washout ratio.

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1-D Air-snowpack modeling of atmospheric nitrous acid at South Pole during ANTCI 2003

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-7087-2008 ◽

2008 ◽

Vol 8 (23) ◽

pp. 7087-7099 ◽

Cited By ~ 24

Author(s):

W. Liao ◽

D. Tan

Keyword(s):

Liquid Layer ◽

Molecular Diffusion ◽

Volume Ratio ◽

Critical Factor ◽

Snow Surface ◽

High Concentration ◽

Nitrite Concentration ◽

Mechanical Dispersion ◽

Quasi Liquid Layer ◽

D Model

Abstract. A 1-D air-snowpack model of HONO has been developed and constrained by observed chemistry and meteorology data. The 1-D model includes molecular diffusion and mechanical dispersion, windpumping in snow, gas phase to quasi-liquid layer phase HONO transfer and quasi-liquid layer nitrate and interstitial air HONO photolysis. Photolysis of nitrate is important as a dominant HONO source inside the snowpack, however, the observed HONO emission from the snowpack was triggered mainly by the equilibrium between quasi liquid layer nitrite and firn air HONO deep down the snow surface (i.e. 30 cm below snow surface). The high concentration of HONO in the firn air is subsequently transported above the snowpack by diffusion and windpumping. The model uncertainties come mainly from lack of measurements and the interpretation of the QLL properties based on the bulk snow measurements. One critical factor is the ionic strength of QLL nitrite, which is estimated here by the bulk snow pH, nitrite concentration, and QLL to bulk snow volume ratio.

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Observation of coinciding arctic boundary layer ozone depletion and snow surface emissions of nitrous acid

Atmospheric Environment ◽

10.1016/j.atmosenv.2005.11.027 ◽

2006 ◽

Vol 40 (11) ◽

pp. 1949-1956 ◽

Cited By ~ 34

Author(s):

Antonio Amoroso ◽

Harry J. Beine ◽

Roberto Sparapani ◽

Marianna Nardino ◽

Ivo Allegrini

Keyword(s):

Boundary Layer ◽

Ozone Depletion ◽

Nitrous Acid ◽

Snow Surface ◽

Arctic Boundary Layer ◽

Boundary Layer Ozone

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Dry deposition on a snow surface

Atmospheric Environment (1967) ◽

10.1016/0004-6981(76)90080-9 ◽

1976 ◽

Vol 10 (9) ◽

pp. 783-785 ◽

Cited By ~ 72

Author(s):

Harald Dovland ◽

Anton Eliassen

Keyword(s):

Dry Deposition ◽

Snow Surface

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THE EFFECT OF ALBEDO-REDUCING MATERIALS ON NET RADIATION AT A SNOW SURFACE

International Association of Scientific Hydrology Bulletin ◽

10.1080/02626667009493933 ◽

1970 ◽

Vol 15 (1) ◽

pp. 69-80 ◽

Cited By ~ 5

Author(s):

W. F. MEGAHAN ◽

J. R. MEIMAN ◽

B. C. GOODELL

Keyword(s):

Snow Surface ◽

Net Radiation

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PRECIPITATION MEASUREMENTS WITH VARIOUS PRECIPITATION GAUGE INSTALLATIONS

Hydrology Research ◽

10.2166/nh.1972.0006 ◽

1972 ◽

Vol 3 (2) ◽

pp. 80-106 ◽

Cited By ~ 3

Author(s):

JOHN SANDSBORG

Keyword(s):

Ground Surface ◽

Spatial Variations ◽

Snow Surface ◽

Great Loss ◽

Extrapolation Procedure ◽

Solid Precipitation ◽

Precipitation Gauge

An account is given of precipitation measurements taken with various precipitation gauge installations at Ultuna, Sweden during 1957-1960. A new gauge constructed to measure small spatial variations in rainfall is described and tested. The difficulty in measuring both rain and snow with the same elevated gauge is demonstrated. An extrapolation procedure is used in an attempt to estimate the snowfall at the snow surface. The great loss in the catch of snow when using elevated gauges (40-50 % at 1.5 m over the ground surface) indicates that this method is very unsatisfactory for measuring solid precipitation.

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The growth of sublimation crystals and surface hoar on the Antarctic plateau

The Cryosphere ◽

10.5194/tc-8-1205-2014 ◽

2014 ◽

Vol 8 (4) ◽

pp. 1205-1215 ◽

Cited By ~ 20

Author(s):

J.-C. Gallet ◽

F. Domine ◽

J. Savarino ◽

M. Dumont ◽

E. Brun

Keyword(s):

Energy Budget ◽

Temperature Drop ◽

Snow Surface ◽

Surface Mass ◽

Antarctic Plateau ◽

Time Variations ◽

Sunny Weather ◽

Frost Flowers ◽

Snow Model ◽

The Antarctic

Abstract. On the Antarctic plateau, precipitation quantities are so low that the surface mass budget is for an important part determined by exchanges of water vapor between the snow surface and the atmosphere surface. At Dome C (75° S, 123° E), we have frequently observed the growth of crystals on the snow surface under calm sunny weather. Here we present the time variations of specific surface area (SSA) and density of these crystals. Using the detailed snow model Crocus, we conclude that the formation of these crystals was very likely due to the nighttime formation of surface hoar crystals and to the daytime formation of sublimation crystals. These latter crystals form by processes similar to those involved in the formation of frost flowers on young sea ice. The formation of these crystals impacts the albedo, mass and energy budget of the Antarctic plateau. In particular, the SSA variations of the surface layer can induce an instantaneous forcing at the snow surface up to −10 W m−2 at noon, resulting in a surface temperature drop of 0.45 K. This result confirms that snow SSA is a crucial variable to consider in the energy budget and climate of snow-covered surfaces.

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Challenges in Modeling Turbulent Heat Fluxes to Snowpacks in Forest Clearings

Journal of Hydrometeorology ◽

10.1175/jhm-d-18-0050.1 ◽

2018 ◽

Vol 19 (10) ◽

pp. 1599-1616 ◽

Cited By ~ 5

Author(s):

Jonathan P. Conway ◽

John W. Pomeroy ◽

Warren D. Helgason ◽

Nicholas J. Kinar

Keyword(s):

Heat Exchange ◽

Surface Temperature ◽

Latent Heat ◽

Turbulent Fluxes ◽

Heat Fluxes ◽

Turbulent Heat ◽

Snow Surface ◽

Turbulent Heat Exchange ◽

Uncertainty Estimates ◽

Model Tuning

Abstract Forest clearings are common features of evergreen forests and produce snowpack accumulation and melt differing from that in adjacent forests and open terrain. This study has investigated the challenges in specifying the turbulent fluxes of sensible and latent heat to snowpacks in forest clearings. The snowpack in two forest clearings in the Canadian Rockies was simulated using a one-dimensional (1D) snowpack model. A trade-off was found between optimizing against measured snow surface temperature or snowmelt when choosing how to specify the turbulent fluxes. Schemes using the Monin–Obukhov similarity theory tended to produce negatively biased surface temperature, while schemes that enhanced turbulent fluxes, to reduce the surface temperature bias, resulted in too much melt. Uncertainty estimates from Monte Carlo experiments showed that no realistic parameter set could successfully remove biases in both surface temperature and melt. A simple scheme that excludes atmospheric stability correction was required to successfully simulate surface temperature under low wind speed conditions. Nonturbulent advective fluxes and/or nonlocal sources of turbulence are thought to account for the maintenance of heat exchange in low-wind conditions. The simulation of snowmelt was improved by allowing enhanced latent heat fluxes during low-wind conditions. Caution is warranted when snowpack models are optimized on surface temperature, as model tuning may compensate for deficiencies in conceptual and numerical models of radiative, conductive, and turbulent heat exchange at the snow surface and within the snowpack. Such model tuning could have large impacts on the melt rate and timing of the snow-free transition in simulations of forest clearings within hydrological and meteorological models.

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Wintertime surface energy balance of a high-altitude seasonal snow surface in Chhota Shigri glacier basin, Western Himalaya

Geological Society London Special Publications ◽

10.1144/sp462.10 ◽

2017 ◽

Vol 462 (1) ◽

pp. 155-168 ◽

Cited By ~ 1

Author(s):

Mohd Soheb ◽

Alagappan Ramanathan ◽

Arindan Mandal ◽

Thupstan Angchuk ◽

Naveen Pandey ◽

...

Keyword(s):

Energy Balance ◽

Surface Energy ◽

High Altitude ◽

Surface Energy Balance ◽

Western Himalaya ◽

Snow Surface ◽

Seasonal Snow ◽

Chhota Shigri Glacier

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The origin of sea salt in snow on Arctic sea ice and in coastal regions

Atmospheric Chemistry and Physics ◽

10.5194/acp-4-2259-2004 ◽

2004 ◽

Vol 4 (9/10) ◽

pp. 2259-2271 ◽

Cited By ~ 87

Author(s):

F. Domine ◽

R. Sparapani ◽

A. Ianniello ◽

H. J. Beine

Keyword(s):

Time Series ◽

Sea Ice ◽

Ozone Depletion ◽

Sea Salt ◽

Sea Spray ◽

Snow Surface ◽

Coastal Regions ◽

Upward Migration ◽

Surface Snow ◽

Frost Flowers

Abstract. Snow, through its trace constituents, can have a major impact on lower tropospheric chemistry, as evidenced by ozone depletion events (ODEs) in oceanic polar areas. These ODEs are caused by the chemistry of bromine compounds that originate from sea salt bromide. Bromide may be supplied to the snow surface by upward migration from sea ice, by frost flowers being wind-blown to the snow surface, or by wind-transported aerosol generated by sea spray. We investigate here the relative importance of these processes by analyzing ions in snow near Alert and Ny-Ålesund (Canadian and European high Arctic) in winter and spring. Vertical ionic profiles in the snowpack on sea ice are measured to test upward migration of sea salt ions and to seek evidence for ion fractionation processes. Time series of the ionic composition of surface snow layers are investigated to quantify wind-transported ions. Upward migration of unfractionated sea salt to heights of at least 17cm was observed in winter snow, leading to Cl- concentration of several hundred µM. Upward migration thus has the potential to supply ions to surface snow layers. Time series show that wind can deposit aerosols to the top few cm of the snow, leading also to Cl- concentrations of several hundred µM, so that both diffusion from sea ice and wind transport can significantly contribute ions to snow. At Ny-Ålesund, sea salt transported by wind was unfractionated, implying that it comes from sea spray rather than frost flowers. Estimations based on our results suggest that the marine snowpack contains about 10 times more Na+ than the frost flowers, so that both the marine snowpack and frost flowers need to be considered as sea salt sources. Our data suggest that ozone depletion chemistry can significantly enhance the Br- content of snow. We speculate that this can also take place in coastal regions and contribute to propagate ODEs inland. Finally, we stress the need to measure snow physical parameters such as permeability and specific surface area to understand quantitatively changes in snow chemistry.

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