Snow analysis, parameterisation of deposition and melting Ekaterina Machulskaya Hydrometeorological Centre of Russian Federation, Moscow, Russia Moscow State University, Russia
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Snow analysis, parameterisation of deposition and melting
Ekaterina Machulskaya
Hydrometeorological Centre of Russian Federation, Moscow, Russia
Moscow State University, Russia
• Motivation
• Snow model description
• Results discussion
• Conclusions and outlook
Outline
Motivation
Snow water-equivalent depth, Valdai, 1972-75
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1 61 121 181 241 301 361 421 481 541 601 661 721 781 841 901
observedsimulated
Snow models description
•Heat conduction•Melting when snow
surfacetemperature > 0°C orwhen soil surface temperature > 0°C
•Heat conduction•Liquid water transport•Gravitational compaction +metamorphosis •Solar radiation penetration
1 layer
Arbitrary number of layers;heat conduction: implicit
(combined with soil heat conduction),latent heat and solar radiation:
source terms
Numerical schemes
Implemented processesTERRA ctrl TERRA + new snow
Implemented processes (2)
- snow temperature, - snow liquid water content,- snow density, - snow specific heat content,
- snow heat conductivity,- latent heat for freezing/melting,
- melting rate, - refreezing rate, - infiltration rate due to gravity
Water percolation:
- snow hydravlic conductivity, - snow water holding capacity,
- snow porosity
Heat and water transport
Gravitational compaction and metamorphosis
describes the gravity effectWhere
term
term describes the snow metamorphosis, = 75 Pa
- the snow compaction viscosity
Solar radiation penetration
Implemented processes (3)
Results discussion: snow water-equivalent depth, Valdai, 1966-1972
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TERRA ctrl
TERRA +new snowobserved
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Results discussion: snow mask, spring 2008
15.03.2008
15.03.2008
ctrl
new
Results discussion: snow water-equivalent depth, spring 2008
new – ctrl
15.03.2008
25.03.2008
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
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
Thank you for your attention!
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