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Author |
Groot Zwaaftink C D, Cagnati A, Crepaz A, Fierz C, Macelloni G, Valt M, Lehning M, |
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Title |
Event-driven deposition of snow on the Antarctic Plateau: analyzing field measurements with SNOWPACK
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Type |
Journal Article |
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Year |
2013 |
Publication |
The Cryosphere |
Abbreviated Journal  |
TC |
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Volume |
7 |
Issue |
1 |
Pages |
333-347 |
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Abstract |
Antarctic surface snow has been studied by means of continuous measurements and observations over a period of 3 yr at Dome C. Snow observations include solid deposits in form of precipitation, diamond dust, or hoar, snow temperatures at several depths, records of deposition and erosion on the surface, and snow profiles. Together with meteorological data from automatic weather stations, this forms a unique dataset of snow conditions on the Antarctic Plateau. Large differences in snow amounts and density exist between solid deposits measured 1 m above the surface and deposition at the surface. We used the snow-cover model SNOWPACK to simulate the snow-cover evolution for different deposition parameterizations. The main adaptation of the model described here is a new event-driven deposition scheme. The scheme assumes that snow is added to the snow cover permanently only during periods of strong winds. This assumption followed from the comparison between observations of solid deposits and daily records of changes in snow height: solid deposits could be observed on tables 1 m above the surface on 94 out of 235 days (40%) while deposition at the surface occurred on 59 days (25%) during the same period, but both happened concurrently on 33 days (14%) only. This confirms that precipitation is not necessarily the driving force behind non-temporary snow height changes. A comparison of simulated snow height to stake farm measurements over 3 yr showed that we underestimate the total accumulation by at least 33%, when the total snow deposition is constrained by the measurements of solid deposits on tables 1 m above the surface. During shorter time periods, however, we may miss over 50% of the deposited mass. This suggests that the solid deposits measured above the surface and used to drive the model, even though comparable to ECMWF forecasts in its total magnitude, should be seen as a lower boundary. As a result of the new deposition mechanism, we found a good agreement between model results and measurements of snow temperatures and recorded snow profiles. In spite of the underestimated deposition, the results thus suggest that we can obtain quite realistic simulations of the Antarctic snow cover by the introduction of event-driven snow deposition. |
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411 |
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ISSN |
1994-0424 |
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yes |
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Call Number |
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Serial |
4506 |
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Author |
Carmagnola C M, Morin S, Lafaysse M, Domine F, Lesaffre B, Lejeune Y, Picard G, Arnaud L, |
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Title |
Implementation and evaluation of prognostic representations of the optical diameter of snow in the SURFEX/ISBA-Crocus detailed snowpack model
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Type |
Journal Article |
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Year |
2014 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
8 |
Issue |
2 |
Pages |
417-437 |
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Abstract |
In the SURFEX/ISBA-Crocus multi-layer snowpack model, the snow microstructure has up to now been characterised by the grain size and by semi-empirical shape variables which cannot be measured easily in the field or linked to other relevant snow properties. In this work we introduce a new formulation of snow metamorphism directly based on equations describing the rate of change of the optical diameter (dopt). This variable is considered here to be equal to the equivalent sphere optical diameter, which is inversely proportional to the specific surface area (SSA). dopt thus represents quantitatively some of the geometric characteristics of a porous medium. Different prognostic rate equations of dopt, including a re-formulation of the original Crocus scheme and the parameterisations from Taillandier et al. (2007) and Flanner and Zender (2006), were evaluated by comparing their predictions to field measurements carried out at Summit Camp (Greenland) in May and June 2011 and at Col de Porte (French Alps) during the 2009/10 and 2011/12 winter seasons. We focused especially on results in terms of SSA. In addition, we tested the impact of the different formulations on the simulated density profile, the total snow height, the snow water equivalent (SWE) and the surface albedo. Results indicate that all formulations perform well, with median values of the RMSD between measured and simulated SSA lower than 10 m2 kg-1. Incorporating the optical diameter as a fully fledged prognostic variable is an important step forward in the quantitative description of the snow microstructure within snowpack models, because it opens the way to data assimilation of various electromagnetic observations. |
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Programme |
1042 |
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Publisher |
Copernicus Publications |
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ISSN |
1994-0424 |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
5199 |
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Author |
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Title |
Using MODIS land surface temperatures and the Crocus snow model to understand the warm bias of ERA-Interim reanalyses at the surface in Antarctica
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Type |
Journal Article |
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Year |
2014 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
8 |
Issue |
4 |
Pages |
1361-1373 |
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Abstract |
based on CALVA-snow activities |
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Programme |
1110 |
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Publisher |
Copernicus Publications |
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ISSN |
1994-0424 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
5206 |
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Author |
Picard G, Royer A, Arnaud L, Fily M, |
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Title |
Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica
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Type |
Journal Article |
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Year |
2014 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
8 |
Issue |
3 |
Pages |
1105-1119 |
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Keywords |
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Abstract |
based on BIPOL and CALVA-snow |
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Programme |
1110 |
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Publisher |
Copernicus Publications |
Place of Publication |
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Series Editor |
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Series Volume |
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Edition |
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ISSN |
1994-0424 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
5207 |
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Author |
Barral H, Genthon C, Trouvilliez A, Brun C, Amory C, |
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Title |
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Type |
Journal Article |
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Year |
2014 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
8 |
Issue |
5 |
Pages |
1905-1919 |
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Keywords |
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Abstract |
Three years of blowing snow observations and associated meteorology along a 7-m mast at site D17 in coastal Adelie Land are presented. The observations are used to address 3 atmospheric moisture issues related to the occurrence of blowing snow, a feature which largely affects many regions of Antarctica: 1) Blowing snow sublimation raises close to saturation the moisture content of the surface atmosphere, and atmospheric models and meteorological analyzes that do not carry blowing snow parameterizations areaffected by a systematic dry bias; 2) While snowpack modeling with a parameterization of surface snow erosion by wind can reproduce the variability of snow accumulation and ablation, ignoring the high levels of atmospheric moisture content associated with blowing snow results in overestimating surface sublimation affecting the energy budget of the snow-pack; 3) the well-known profile method to calculate turbulent moisture fluxes is not applicable when blowing snow occurs, because moisture gradients are weak due to blowing snow sublimation, and the impact of measurement uncertainties are strongly amplified in case of strong winds.
Keywords: Antarctica, Snowpack, Surface Mass Balance, Katabatic flow, Blowing snow, Sublimation, Latent Heat Fluxes, Moisture, Observation, Modelling, Profile method,Monin and Obukhov similarity theory, Uncertainty propagation
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Programme |
1013 |
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Thesis |
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Publisher |
Copernicus GmbH |
Place of Publication |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
1994-0416 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
6015 |
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Author |
Domine F, Barrere M, Sarrazin D, Morin S, Arnaud L, |
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Title |
Automatic monitoring of the effective thermal conductivity of snow in a low-Arctic shrub tundra
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Type |
Journal Article |
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Year |
2015 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
9 |
Issue |
3 |
Pages |
1265-1276 |
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Keywords |
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Abstract |
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Programme |
1042 |
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Copernicus GmbH |
Place of Publication |
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ISSN |
1994-0416 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
6116 |
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Journal Article |
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Year |
2015 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
9 |
Issue |
4 |
Pages |
1373-1383 |
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Keywords |
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Abstract |
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Programme |
1013 |
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Publisher |
Copernicus GmbH |
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ISSN |
1994-0416 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
6143 |
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Author |
Champollion N, Picard G, Arnaud L, Lefebvre E, Fily M, |
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Title |
Hoar crystal development and disappearance at Dome C, Antarctica: observation by near-infrared photography and passive microwave satellite |
Type |
Journal Article |
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Year |
2013 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
7 |
Issue |
4 |
Pages |
1247-1262 |
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Keywords |
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Abstract |
Hoar crystals episodically cover the snow surface in Antarctica and affect the roughness and reflective properties of the airsnow interface. However, little is known about their evolution and the processes responsible for their development and disappearance despite a probable influence on the surface mass balance and energy budget. To investigate hoar evolution, we use continuous observations of the surface by in situ near-infrared photography and by passive microwave remote sensing at Dome C in Antarctica. From the photography data, we retrieved a daily indicator of the presence/absence of hoar crystals using a texture analysis algorithm. The analysis of this 2 yr long time series shows that Dome C surface is covered almost half of the time by hoar. The development of hoar crystals takes a few days and seems to occur whatever the meteorological conditions. In contrast, the disappearance of hoar is rapid (a few hours) and coincident with either strong winds or with moderate winds associated with a change in wind direction from southwest (the prevailing direction) to southeast. From the microwave satellite data, we computed the polarisation ratio (i.e. horizontal over vertical polarised brightness temperatures), an indicator known to be sensitive to hoar in Greenland. Photography data and microwave polarisation ratio are correlated, i.e. high values of polarisation ratio which theoretically correspond to low snow density values near the surface are associated with the presence of hoar crystals in the photography data. Satellite data over nearly ten years (20022011) confirm that a strong decrease of the polarisation ratio (i.e. signature of hoar disappearance) is associated with an increase of wind speed or a change in wind direction from the prevailing direction. The photography data provides, in addition, evidence of interactions between hoar and snowfall. Further adding the combined influence of wind speed and wind direction results in a complex picture of the snowatmosphere interactions in Antarctica which deserves further quantification and modelling. |
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Programme |
1110 |
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Series Issue |
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ISSN |
1994-0424 |
ISBN |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
4489 |
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Author |
Amory, C., A. Trouvilliez, H. Gallée, F. Naaim-Bouvet, C. Genthon, V. favier, C. Agosta, L. Piard, and H. bellot |
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Title |
Comparison of aeolian snow transport events and snow mass fluxes between observations and simulations made by the regional climate model MAR in Adélie Land, East Antarctica |
Type |
Journal Article |
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Year |
2015 |
Publication |
The Cryosphere |
Abbreviated Journal |
TC |
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Volume |
9 |
Issue |
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Pages |
1373-1383 |
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Keywords |
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Abstract |
Using the original setup described in Gallée et al. (2013), the MAR regional climate model including a coupled snowpack/aeolian snow transport parameterization, was run at a fine spatial (5 km horizontal and 2 m vertical) resolution over 1 summer month in coastal Adélie Land. Different types of feedback were taken into account in MAR including drag partitioning caused by surface roughness elements. Model outputs are compared with observations made at two coastal locations, D17 and D47, situated respectively 10 and 100 km inland. Wind speed was correctly simulated with positive values of the Nash test (0.60 for D17 and 0.37 for D47) but wind velocities above 10 m s−1 were underestimated at both D17 and D47; at D47, the model consistently underestimated wind velocity by 2 m s−1. Aeolian snow transport events were correctly reproduced with the right timing and a good temporal resolution at both locations except when the maximum particle height was less than 1 m. The threshold friction velocity, evaluated only at D17 for a 7-day period without snowfall, was overestimated. The simulated aeolian snow mass fluxes between 0 and 2 m at D47 displayed the same variations but were underestimated compared to the second-generation FlowCaptTM values, as was the simulated relative humidity at 2 m above the surface. As a result, MAR underestimated the total aeolian horizontal snow transport for the first 2 m above the ground by a factor of 10 compared to estimations by the second-generation FlowCaptTM. The simulation was significantly improved at D47 if a 1-order decrease in the magnitude of z0 was accounted for, but agreement with observations was reduced at D17. Our results suggest that z0 may vary regionally depending on snowpack properties, which are involved in different types of feedback between aeolian transport of snow and z0. |
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Programme |
1013 |
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ISSN |
1994-0416 |
ISBN |
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Approved |
yes |
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Call Number |
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Serial |
6312 |
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Author |
Pisanu B. & Bain O. |
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Title |
Aonchotheca musimon n.sp. (Nematoda: Capillariinae) from the mouflon Ovis musimon in the sub-Antarctic Kerguelen archipelago, with comments on the relationships with A. bilobata (Bhalero, 1933) Moravec, 1982 and other species of the genus. |
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Journal Article |
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Year |
1999 |
Publication |
Systematic parasitology |
Abbreviated Journal |
Syst. Parasitol. |
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Volume |
43 |
Issue |
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Pages |
17-24 |
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Abstract |
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Programme |
276 |
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ISSN |
0165-5752 |
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Approved |
yes |
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Call Number |
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Serial |
790 |
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