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Snow analysis, parameterisation of deposition and melting

Explore the implementation of a new snow parameterization scheme in TERRA model for improved snow evolution representation. This study details the processes involved, numerical schemes applied, and results from Valdai long-term data. The enhanced model offers a more realistic depiction, especially during melting periods. Future work includes evaluation in COSMO-EU domain, operational mode verification, code consolidation, and testing in the COSMO-RU domain.

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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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