Modelling the surface mass balance evolution of Saint Sorlin glacier

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Modelling the surface mass balance evolution of
Saint Sorlin glacier
Laboratoire de Glaciologie et  Géophysique de
l'Environnement
Martin Gerbaux Christophe Genthon Pierre
Etchevers Christian Vincent 
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Outline

• The snow/ice Crocus model
• Saint Sorlin Glacier
• Mass balance modelling
• Results
• Conclusion and prospects

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The snow/ice Crocus model

• Developed by the Centre dEtude de la Neige
• 1 dimension model
• Pile of layers parallel to the ground
• Combined with Safran meteorology for operational
  avalanches forecasting

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The snow/ice Crocus model
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The snow/ice Crocus model

• Input meteorological variables
• Air temperature
• Air humidity
• Wind speed
• Incoming direct solar radiation
• Incoming scattered solar radiation
• Incoming longwave radiation
• Cloudiness
• Amount and phase of precipitation

• Use of Safran meteorology and adjustment of
  precipitations (single factor)

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Examples of Crocus output
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Saint Sorlin Glacier

• Located in the Grandes Rousses area, in French
  Alps

• Small Glacier (3km2)

• Altitude from 2690m to 3400m

• Orientation North and East

• Well monitored

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Location of measurements
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Modelling

• Safran precipitations adjusted to be in accord
  with measurements

• Gridding of the glacier (step of 250m)

• At each grid point, calculate of orientation,
  slope, mask and input meteorological data, then
  run Crocus

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Mass balance evolution during the 98/99 season
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Annual mass balance
Balance 94/95 -0.67 mwe
Balance 95/96 -0.36 mwe
Balance 96/97 0.43 mwe
Balance 97/98 -1.45 mwe
Balance 98/99 -0.80 mwe
Balance 99/00 -1.06 mwe
Balance 00/01 -0.33 mwe
Balance 01/02 -1.27 mwe
Mean annual mass Balance 94/02 -0.69 mwe
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Conclusion and prospects

• Reasonable first results
• Continue validation with new field data
• Validate equilibrium line with photographs and
  satellites

• Modelling the past decades with ECMWF ERA 40
  meteorological data as input
• Modelling XX century with GCM
• Forecasting of the future evolution with climatic
  scenari and extend to other glaciers