Factors Affecting Variations of Snow Surface Temperature and Air Temperature Over Sea Ice in Winter

AbstractSnow surface temperature (Ts) plays an important role in the formation of surface hoar or near-surface faceted crystals The goal of this study was to obtain detailed information on Ts in different forest stands nelr the timberline. The investigations were conducted during clear nights and showed that the snow surface temperature is influenced very strongly by the forest canopy. While the air temperature was very similar on the different experimental sites, Ts was higher in the forest than in the open field; on the south-facing slope the difference between the forest and the open field was 3–4.5°C, and on the north-facing slope approximately 3–7°C. Taking into account that εair is 0.7 and εtree is 0.94, the incoming radiation (I ↓) for the different experimental sites was calculated by the equation of Brunt (the canopy density was estimated using photographs taken with an 8 mm fish-eye). To calculate Ts, air temperature and averaged values of the net radiation (because the net radiation (I) has only a small range of variation during clear nights) were used. The results show that the calculated values were higher than the measured values (by approximately 2°C). However, a better correlation was found by using lower values of the emissivity (εair0.67 and εtree0.91).

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Aerodynamic and Radiative Controls on the Snow Surface Temperature

Journal of Hydrometeorology ◽

10.1175/jhm-d-15-0226.1 ◽

2016 ◽

Vol 17 (8) ◽

pp. 2175-2189 ◽

Cited By ~ 8

Author(s):

J. W. Pomeroy ◽

R. L. H. Essery ◽

W. D. Helgason

Keyword(s):

Surface Temperature ◽

Air Temperature ◽

Infrared Radiation ◽

Near Infrared ◽

Longwave Radiation ◽

Snow Surface ◽

State Variables ◽

Near Infrared Radiation ◽

Snow Surface Temperature ◽

Aerodynamic Roughness

Abstract The snow surface temperature (SST) is essential for estimating longwave radiation fluxes from snow. SST can be diagnosed using finescale multilayer snow physics models that track changes in snow properties and internal energy; however, these models are heavily parameterized, have high predictive uncertainty, and require continuous simulation to estimate prognostic state variables. Here, a relatively simple model to estimate SST that is not reliant on prognostic state variables is proposed. The model assumes that the snow surface is poorly connected thermally to the underlying snowpack and largely transparent for most of the shortwave radiation spectrum, such that a snow surface energy balance among only sensible heat, latent heat, longwave radiation, and near-infrared radiation is possible and is called the radiative psychrometric model (RPM). The RPM SST is sensitive to air temperature, humidity, ventilation, and longwave irradiance and is secondarily affected by absorption of near-infrared radiation at the snow surface that was higher where atmospheric deposition of particulates was more likely to be higher. The model was implemented with neutral stability, an implicit windless exchange coefficient, and constant shortwave absorption factors and aerodynamic roughness lengths. It was evaluated against radiative SST measurements from the Canadian Prairies and Rocky Mountains, French Alps, and Bolivian Andes. With optimized and global shortwave absorption and aerodynamic roughness length parameters, the model is shown to accurately predict SST under a wide range of conditions, providing superior predictions when compared to air temperature, dewpoint, or ice bulb calculation approaches.

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Evaluation of alternative formulae for calculation of surface temperature in snowmelt models using frequency analysis of temperature observations

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-3863-2009 ◽

2009 ◽

Vol 6 (3) ◽

pp. 3863-3890 ◽

Cited By ~ 3

Author(s):

C. H. Luce ◽

D. G. Tarboton

Keyword(s):

Time Series ◽

Energy Balance ◽

Surface Temperature ◽

Energy Flux ◽

Frequency Analysis ◽

Energy Content ◽

Balance Model ◽

Snow Surface ◽

Fourier Frequency ◽

Snow Surface Temperature

Abstract. The snow surface temperature is an important quantity in the snow energy balance, since it modulates the exchange of energy between the surface and the atmosphere as well as the conduction of energy into the snowpack. It is therefore important to correctly model snow surface temperatures in energy balance snowmelt models. This paper focuses on the relationship between snow surface temperature and conductive energy fluxed that drive the energy balance of a snowpack. Time series of snow temperature at the surface and through the snowpack were measured to examine energy conduction in a snowpack. Based on these measurements we calculated the snowpack energy content and conductive energy flux at the snow surface. We then used these estimates of conductive energy flux to evaluate formulae for the calculation of the conductive flux at the snow surface based on surface temperature time series. We use a method based on Fourier frequency analysis to estimate snow thermal properties. Among the formulae evaluated, we found that a modified force-restore formula, based on the superimposition of the force-restore equation capturing diurnal fluctuations on a gradually changing temperature gradient, had the best agreement with observations of heat conduction. This formula is suggested for the parameterization of snow surface temperature in a full snowpack energy balance model.

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Driving Forces of Circum-Antarctic Glacier and Ice Shelf Front Retreat over the Last Two Decades

10.5194/tc-2020-224 ◽

2020 ◽

Cited By ~ 1

Author(s):

Celia A. Baumhoer ◽

Andreas J. Dietz ◽

Christof Kneisel ◽

Heiko Paeth ◽

Claudia Kuenzer

Keyword(s):

Sea Ice ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Air Temperature ◽

Environmental Variables ◽

Sea Surface ◽

Ice Shelf ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

The Antarctic

Abstract. The safety band of Antarctica consisting of floating glacier tongues and ice shelves buttresses ice discharge of the Antarctic Ice Sheet. Recent disintegration events of ice shelves and glacier retreat indicate a weakening of this important safety band. Predicting calving front retreat is a real challenge due to complex ice dynamics in a data-scarce environment being unique for each ice shelf and glacier. We explore to what extent easy to access remote sensing and modelling data can help to define environmental conditions leading to calving front retreat. For the first time, we present a circum-Antarctic record of glacier and ice shelf front retreat over the last two decades in combination with environmental variables such as air temperature, sea ice days, snowmelt, sea surface temperature and wind direction. We find that the Antarctic ice sheet area shrank 29,618 ± 29 km2 in extent between 1997–2008 and gained an area of 7,108 ± 144.4 km2 between 2009 and 2018. Retreat concentrated along the Antarctic Peninsula and West Antarctica including the biggest ice shelves Ross and Ronne. Glacier and ice shelf retreat comes along with one or several changes in environmental variables. Decreasing sea ice days, intense snow melt, weakening easterlies and relative changes in sea surface temperature were identified as enabling factors for retreat. In contrast, relative increases in air temperature did not correlate with calving front retreat. To better understand drivers of glacier and ice shelf retreat it is of high importance to analyse the magnitude of basal melt through the intrusion of warm Circumpolar Deep Water (CDW) driven by strengthening westerlies and to further assess surface hydrology processes such as meltwater ponding, runoff and lake drainage.

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Modeling the snow surface temperature with a one-layer energy balance snowmelt model

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-15071-2013 ◽

2013 ◽

Vol 10 (12) ◽

pp. 15071-15118 ◽

Cited By ~ 2

Author(s):

J. You ◽

D. G. Tarboton ◽

C. H. Luce

Keyword(s):

Energy Balance ◽

Surface Temperature ◽

Snow Water Equivalent ◽

Effective Conductivity ◽

Energy Content ◽

Single Layer ◽

Conductive Heat ◽

Snow Surface ◽

Snow Surface Temperature ◽

Snowmelt Model

Abstract. \\label{sec:abstract} Snow surface temperature is a key control on energy exchanges at the snow surface, particularly net longwave radiation and turbulent energy fluxes. The snow surface temperature is in turn controlled by the balance between various external fluxes and the conductive heat flux, internal to the snowpack. Because of the strong insulating properties of snow, thermal gradients in snow packs are large and nonlinear, a fact that has led many to advocate multiple layer snowmelt models over single layer models. In an effort to keep snowmelt modeling simple and parsimonious, the Utah Energy Balance (UEB) snowmelt model used only one layer but allowed the snow surface temperature to be different from the snow average temperature by using an equilibrium gradient parameterization based on the surface energy balance. Although this procedure was considered an improvement over the ordinary single layer snowmelt models, it still resulted in discrepancies between modeled and measured snowpack energy contents. In this paper we examine the parameterization of snow surface temperature in single layer snowmelt models from the perspective of heat conduction into a semi-infinite medium. We evaluate the equilibrium gradient approach, the force-restore approach, and a modified force-restore approach. In addition, we evaluate a scheme for representing the penetration of a refreezing front in cold periods following melt. We also introduce a method to adjust effective conductivity to account for the presence of ground near to a shallow snow surface. These parameterizations were tested against data from the Central Sierra Snow Laboratory, CA, Utah State University experimental farm, UT, and Subnivean snow laboratory at Niwot Ridge, CO. These tests compare modeled and measured snow surface temperature, snow energy content, snow water equivalent, and snowmelt outflow. We found that with these refinements the model is able to better represent the snowpack energy balance and internal energy content while still retaining a parsimonious one layer format.

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Evaluation of alternative formulae for calculation of surface temperature in snowmelt models using frequency analysis of temperature observations

Hydrology and Earth System Sciences ◽

10.5194/hess-14-535-2010 ◽

2010 ◽

Vol 14 (3) ◽

pp. 535-543 ◽

Cited By ~ 31

Author(s):

C. H. Luce ◽

D. G. Tarboton

Keyword(s):

Time Series ◽

Energy Balance ◽

Surface Temperature ◽

Energy Flux ◽

Frequency Analysis ◽

Energy Content ◽

Balance Model ◽

Snow Surface ◽

Fourier Frequency ◽

Snow Surface Temperature

Abstract. The snow surface temperature is an important quantity in the snow energy balance, since it modulates the exchange of energy between the surface and the atmosphere as well as the conduction of energy into the snowpack. It is therefore important to correctly model snow surface temperatures in energy balance snowmelt models. This paper focuses on the relationship between snow surface temperature and conductive energy fluxes that drive the energy balance of a snowpack. Time series of snow temperature at the surface and through the snowpack were measured to examine energy conduction in a snowpack. Based on these measurements we calculated the snowpack energy content and conductive energy flux at the snow surface. We then used these estimates of conductive energy flux to evaluate formulae for the calculation of the conductive flux at the snow surface based on surface temperature time series. We use a method based on Fourier frequency analysis to estimate snow thermal properties. Among the formulae evaluated, we found that a modified force-restore formula, based on the superimposition of the force-restore equation capturing diurnal fluctuations on a gradually changing temperature gradient, had the best agreement with observations of heat conduction. This formula is suggested for the parameterization of snow surface temperature in a full snowpack energy balance model.

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Daytime preservation of surface-hoar crystals

Annals of Glaciology ◽

10.1017/s0260305500014488 ◽

1998 ◽

Vol 26 ◽

pp. 22-26 ◽

Cited By ~ 10

Author(s):

Akihiro Hachikubo ◽

Eizi Akitaya

Keyword(s):

Shear Strength ◽

Surface Layer ◽

Relative Humidity ◽

Solar Radiation ◽

Surface Temperature ◽

Snow Surface ◽

Previous Night ◽

Snow Surface Temperature ◽

Transfer Method

Surface hoar growing for several clear and humid days were observed. During daytime, air and snow-surface temperature increased and relative humidity decreased, hence evaporation (sublimation) occurred at the snow surface. The amount of evaporation calculated using a bulk-transfer method suggests that the surface-hoar crystals which grew during the previous night should have disappeared but they were observed to survive on the snow surface even during the daytime. During the following night, new surface-hoar crystals formed on top of the older ones and grew even larger. This result indicates that, although the surface-hoar crystals evaporated into the air during the daytime, snow grains beneath the surface were warmed by solar radiation and evaporated to the air. They may partially condense into the surface-hoar crystals and make up for the reduction in size. Depth-hoar crystals formed beneath the snow surface for several days and the surface layer, composed of both types of hoar crystal, showed a very weak shear strength.

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