Parameterization of snow vertical structure and representation of the corresponding snow properties in local climate modeling Andrey B. Shmakin (Institute of Geography, Russian Academy of Sciences) Sergey A. Sokratov (Moscow State University) INTAS-funded project 03-51-5296 «Influence of snow vertical structure on hydrothermal regime and snow-related economical aspects in Northern Eurasia» - Technical University, Vienna - Institute of Geography, Moscow - Moscow State University - Hydrometeorological Center of Russia, Moscow - Charles University, Prague - Swiss Federal Institute for Snow and Avalanches Research, Davos - Institute of Geology and Geophysics, Tashkent, Uzbekistan - Institute of Hydrology, Slovakia Quantitative Qualitative methods for The approaches for evaluation project description of snow cover of snow structure, parameters its stratigraphy, in mathematical crystal formation, modeling etc. RESEARCH OBJECTIVES -Creation of a data set of snow stratigraphy in Northern Eurasia; -Development of classification of the snow cover and its effective properties for Northern Eurasia; -Development of parameterization schemes of the snow cover stratigraphy for climate and hydrological models, and their testing against the observed data; -Estimation of the influence of the snow cover stratigraphy on hydrothermal regime in the Northern Eurasia and extreme events; - Estimation of the economic effect of the snow cover spatial and temporal variability in the Northern Eurasia, and its projection for certain future climate change scenarios. Changes in time of the snow vertical structure (from SNOWPACK model and observations), Weissfluhjoch, February – April, 1999. The colors correspond to different types of snow crystals with certain surface curvature and other characteristics. Basically, each type carries a set of effective parameters (density, thermal conductivity, liquid water holding capacity, etc.). Then, integral effective parameters for the entire snow profile are calculated and used in local model of energy/water exchange on the land. The heat conductivity evaluation: combining continuity of flux and energy conservation at the surface M f pM ksn 1 1 di da ki ad 1 di 1 da k p k pht id fi ic ac where is the dimensionless snow porosity; di is the fraction of discontinuous ice, da is the same for discontinuous air, both varying from 0 to 1; ki is the heat conductivity of ice; kp is the same for the mechanisms of the heat conduction and convection in the pore space; kpht is the “equivalent heat conductivity” of the process of alternating latent heat release/gain; fMi and fMp are macroscale gradient enhancements for ice and pores, χadic and χidac are structure factors for continuous ice with dispersed pores and for continuous air with dispersed ice. Previously, data on internal geometry of the snow crystals were unavailable, and there was no the equation combining the porous media with anisotropic matter. At the next stage, liquid water holding capacity of the snow will be modified according to the crystal type. Also, possibility of multiple snow layers will be allowed in the model. Testing site Dukant, Uzbekistan (41°09’N, 70°04’E, 2000 and 2250 m a.s.l.), Jan. – Apr. 1990 (Courtesy of Dr.Maxim Petrov and his team from the INTAS project) Daily average air temperature (°C) at Dukant in January-April, 1990 20 15 10 5 0 101 106 111 116 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 1 6 -5 -10 The atmospheric -15 forcing parameters also include: Daily precipitation sums (cm, blue) and average - wind speed, effective cloudiness (fraction, brown) at Dukant in - air humidity, January-April, 1990 - daily range of air 5 temperature. 4 3 2 1 0 101 106 111 116 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 1 6 Snow depth (cm) at Dukant in January-April, 1990, according to observations (blue), calculations with heat conductivity by Sturm (1992; green), and by the new method (red) 120 100 80 60 40 20 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 Snow depth (cm) at Point 28 in January-April, 1990, according to observations (blue diamonds), calculations with heat conductivity by Sturm (1992; green), and by the new method (red) 200 150 100 50 0 101 106 111 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 1 6 Soil surface temperature (°C) at Point 28 in January- April, 1990, according to observations (blue diamonds), calculations with heat conductivity by Sturm (1992; green) and by the new method (red) 0 101 106 111 116 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 1 6 -0,5 -1 -1,5 -2 -2,5 -3 Conclusions - Parameterization of the snow heat conductivity is developed, based on the structure of snow crystals, their density and temperature. Information of main types of the snow (fluffy, small-grain, depth hoar, etc.) fit to the procedure. - Snow depth can be sensitive to the method of snow heat conductivity evaluation, depending on the weather conditions. At Dukant, it provides higher accuracy in modeling of the snow depth dynamics. Climate modeling with the new snow scheme is expected to benefit from the new procedure. - The new method results in more accurate soil surface temperature calculation. This will allow better evaluation of snow-related processes (soil thermal regime, hydrology, etc.) in the project. FURTHER DEVELOPMENT OF THE PROJECT At the next stage, the snow types recognition will be formalized according to the evolution of atmospheric conditions during winter season, and landscape features (presence of tall vegetation, etc.). Then, the heat/water exchange blocks of SPONSOR model will be interactively incorporated in global climate models as parameterization schemes. The snow cover vertical structure will appear as a result of weather variations, and influence them in turn. A series of numerical experiments will be carried out for contemporary climate conditions and some future scenarios. The results will be analyzed from the viewpoint of both average regime and extreme events. Projections of the economical effects in Northern Eurasia due to climate change and corresponding snow properties change will be made. Thank you!
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