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Snow analysis, parameterisation of deposition and melting

Snow analysis, parameterisation of deposition and melting. Ekaterina Machulskaya Hydrometeorological Centre of Russian Federation, Moscow, Russia Moscow State University, Russia. Outline. Motivation Snow model description Results discussion Conclusions and outlook. Motivation.

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Snow analysis, parameterisation of deposition and melting

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  1. Snow analysis, parameterisation of deposition and melting Ekaterina Machulskaya Hydrometeorological Centre of Russian Federation, Moscow, Russia Moscow State University, Russia

  2. Outline • Motivation • Snow model description • Results discussion • Conclusions and outlook

  3. Motivation

  4. Snow models description TERRA + new snow TERRA ctrl Implemented processes • Heat conduction • Liquid water transport • Gravitational compaction + • metamorphosis • Solar radiation penetration • Heat conduction • Melting when snow surface • temperature > 0°C or • when soil surface • temperature > 0°C Numerical schemes Arbitrary number of layers; heat conduction: implicit (combined with soil heat conduction), latent heat and solar radiation: source terms 1 layer

  5. Implemented processes (2) Heat and water transport - snow temperature, - snow liquid water content, - snow heat conductivity, - latent heat for freezing/melting, - snow density, - snow specific heat content, - melting rate, - refreezing rate, - infiltration rate due to gravity Water percolation: - snow hydravlic conductivity, - snow water holding capacity, - snow porosity

  6. Gravitational compaction and metamorphosis Implemented processes (3) Where term describes the gravity effect term describes the snow metamorphosis, = 75 Pa - the snow compaction viscosity Solar radiation penetration

  7. Results discussion: snow water-equivalent depth, Valdai, 1966-1972

  8. Results discussion: snow mask, spring 2008 ctrl 15.03.2008 new 15.03.2008

  9. Results discussion: snow water-equivalent depth, spring 2008 new – ctrl 25.03.2008 15.03.2008

  10. Summary • A new, more physically based parameterization of snow is suggested and implemented into TERRA-standalone. As the main component, this scheme includes description of the water phase transitions within snowpack. • By means of the Valdai long-term data an comparison with the current snow model incorporated in COSMO is done. The new scheme represents the snow evolution more realistically, particularly during melting period. Ongoing work • Evaluation of the results obtained for the COSMO-EU domain during off-line experiments

  11. Outlook • Verification of the new model in operational mode • Code consolidation + scientific and technical documentation • Winter 2008/09: verification of the new scheme for the COSMO-RU domain

  12. Thank you for your attention!

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