The detailed snowpack scheme Crocus and its implementation in SURFEX v7.2

Vionnet, Vincent; Brun, E.; Morin, Samuel; Boone, Aaron; Faroux, Stéphanie; Moigne, Patrick Le; Martin, E.; Willemet, Jean-Marie

doi:10.5194/gmd-5-773-2012

Cited by 552 publications

(718 citation statements)

References 62 publications

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“…We used Terra MOD11 and Aqua MYD11 products in version-5. These products were evaluated by Wan (2014) with the radiancebased method: using atmospheric temperature and water profiles and surface emissivity, the radiance-based method calculates MODIS LST values from brightness temperatures in band 31 through radiative transfer simulations. By applying this method on 42 sites, Wan (2014) found MODIS T s errors within ±2 • C for all the sites but six bare soil sites (not including South Pole).…”

Section: Modis Land Surface Temperaturementioning

confidence: 99%

“…These products were evaluated by Wan (2014) with the radiancebased method: using atmospheric temperature and water profiles and surface emissivity, the radiance-based method calculates MODIS LST values from brightness temperatures in band 31 through radiative transfer simulations. By applying this method on 42 sites, Wan (2014) found MODIS T s errors within ±2 • C for all the sites but six bare soil sites (not including South Pole). For the South Pole site, MODIS LST error is only −0.5 • C. The accuracy of MODIS LST values depends primarily on the quality of the detection of clouds (Hall et al, 2008).…”

Section: Modis Land Surface Temperaturementioning

confidence: 99%

“…Within the modeling platform SURFEX (EXTernalized land and ocean SURFace platform) (Masson et al, 2013), the Crocus snowpack model (Brun et al, 1992;Vionnet et al, 2012) was run in a stand-alone mode, using meteorological forcing data from ERA-Interim. The ERA-Interim total precipitation was turned into snowfall at temperatures below 1 • C and into rainfall above.…”

Section: Surface Temperature Simulation Using Crocus Snowpack Modelmentioning

confidence: 99%

“…Such an evaluation provides better insight than previous evaluations based on a comparison with near-surface temperature, as in Wang et al (2013). In the second section, MODIS LST values from 2000 to 2011 are compared with 3 h ERA-Interim (Dee et al, 2011) snow surface temperatures and hourly snow surface temperatures simulated by the detailed snowpack model Crocus (Brun et al, 1992;Vionnet et al, 2012). A warm bias is found and its spatial and temporal variations are analyzed.…”

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confidence: 99%

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Using MODIS land surface temperatures and the Crocus snow model to understand the warm bias of ERA-Interim reanalyses at the surface in Antarctica

et al. 2014

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Abstract. Moderate-Resolution Imaging spectroradiometer (MODIS) land surface temperatures in Antarctica were processed in order to produce a gridded data set at 25 km resolution, spanning the period 2000-2011 at an hourly time step. The Aqua and Terra orbits and MODIS swath width, combined with frequent clear-sky conditions, lead to very high availability of quality-controlled observations: on average, hourly data are available 14 h per day at the grid points around the South Pole and more than 9 h over a large area of the Antarctic Plateau. Processed MODIS land surface temperatures, referred to hereinafter as MODIS T s values, were compared with in situ hourly measurements of surface temperature collected over the entirety of the year 2009 by seven stations from the Baseline Surface Radiation Network (BSRN) and automatic weather stations (AWSs). In spite of an occasional failure in the detection of clouds, MODIS T s values exhibit a good performance, with a bias ranging from −1.8 to 0.1 • C and errors ranging from 2.2 to 4.8 • C root mean square at the five stations located on the plateau. These results show that MODIS T s values can be used as a precise and accurate reference to test other surface temperature data sets. Here, we evaluate the performance of surface temperature in the European Centre for MediumRange Weather Forecasts (ECMWF) reanalysis known as ERA-Interim reanalysis. During conditions detected as cloud free by MODIS, ERA-Interim shows a widespread warm bias in Antarctica in every season, ranging from +3 to +6 • C on the plateau. This confirms a recent study which showed that the largest discrepancies in 2 m air temperature between ERA-Interim and the global temperature data set HadCRUT4 compiled by the Met Office Hadley Centre and the University of East Anglia's Climatic Research Unit occur in Antarctica. A comparison with in situ surface temperature shows that this bias is not strictly limited to clear-sky conditions. A detailed comparison with stand-alone simulations by the Crocus snowpack model, forced by ERA-Interim, and with the ERA-Interim/land simulations, shows that the warm bias may be due primarily to an overestimation of the surface turbulent fluxes in very stable conditions. Numerical experiments with Crocus show that a small change in the parameterization of the effects of stability on the surface exchange coefficients can significantly impact the snow surface temperature. The ERA-Interim warm bias appears to be likely due to an overestimation of the surface exchange coefficients under very stable conditions.

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Section: Modis Land Surface Temperaturementioning

confidence: 99%

Section: Modis Land Surface Temperaturementioning

confidence: 99%

Section: Surface Temperature Simulation Using Crocus Snowpack Modelmentioning

confidence: 99%

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confidence: 99%

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Using MODIS land surface temperatures and the Crocus snow model to understand the warm bias of ERA-Interim reanalyses at the surface in Antarctica

et al. 2014

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“…To avoid confusion between surface hoar and sublimation crystals, we will avoid the term of "frost" in this paper. To better characterize the possibility of forming sublimation crystals on the Antarctic plateau, we used the Crocus snow model (Vionnet et al, 2012) and the formalism of Style and Worster (2009). We report here these field and modeling studies and attempt to derive implications for the energy and mass balance of the Antarctic plateau.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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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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Modeling the impact of snow drift on the decameter-scale variability of snow properties on the Antarctic Plateau

Libois

Picard

Arnaud

et al. 2014

J. Geophys. Res. Atmos.

133

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The annual accumulation and the physical properties of snow close to the surface on the Antarctic Plateau are characterized by a large decameter‐scale variability resulting from snow drift that is not simulated by one‐dimensional snow evolution models. Here, the detailed snowpack model Crocus was adapted to Antarctic conditions and then modified to account for this drift‐induced variability using a stochastic snow redistribution scheme. For this, 50 simulations were run in parallel and were allowed to exchange snow mass according to rules driven by wind speed. These simple rules were developed and calibrated based on in situ pictures of the snow surface recorded for two years. The simulation performed with this new model shows three substantial improvements with respect to standard Crocus simulations. First, significant and rapid variations of snow height observed in hourly measurements are well reproduced, highlighting the crucial role of snow drift in snow accumulation. Second, the statistics of annual accumulation is also simulated successfully, including the years with net ablation which are as frequent as 15% in the observations and 11% in the simulation. Last, the simulated vertical profiles of snow density and specific surface area down to 50 cm depth were compared to 98 profiles measured at Dome C during the summer 2012–2013. The observed spatial variability is partly reproduced by the new model, especially close to the surface. The erosion/deposition processes explain why layers with density lower than 250 kg m−3 or specific surface area larger than 30 m2 kg−1 can be found deeper than 10 cm.

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The detailed snowpack scheme Crocus and its implementation in SURFEX v7.2

Cited by 552 publications

References 62 publications

Using MODIS land surface temperatures and the Crocus snow model to understand the warm bias of ERA-Interim reanalyses at the surface in Antarctica

Using MODIS land surface temperatures and the Crocus snow model to understand the warm bias of ERA-Interim reanalyses at the surface in Antarctica

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

Modeling the impact of snow drift on the decameter-scale variability of snow properties on the Antarctic Plateau

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