Motivation: Permafrost is thawing for various reasons. Since thawing permafrost affects economy and ecosystems as well as weather and climate in various ways it is important to be able to simulate permafrost dynamics and the active layer well in weather forecast, climate and Arctic system models.
Goal: The aim of our activities is to simulate frozen ground behavior, investigate the interaction ecosystems-permafrost-climate and test the hypothesis that an increased active layer may yield to more cloud and precipitation formation, especially thunderstorms.
Method: We developed a frozen ground routine for the hydrothermo-dynamics soil vegetation scheme (HTSVS).
Results: HTSVS has been implemented and tested in GESIMA, MM5 and CCSM2.0.1. The frozen ground module has been evaluated by lysimeter, ATLAS, BALTEX, and IARC permafrost data (e.g. Mölders et al. 2003a, 2003b, Spier and Mölders 2005, Majhi 2004, Narapussetty and Mölders 2005, Mölders and Romanovsky 2006). Simulations without and with consideration of permafrost show notable impact on loacl weather (Mölders and Walsh 2004). The Crank-Nicholson finite differences scheme used to solve the partial differential equations for heat and moisture transfer yields to a slight offset in capturing the phase of the soil temperature and moisture evolution; Galerkin finite elemente provide better results, but are currently computationally too expensive for use in climate or Arctic system models (Narapussetty 2005, Narapussetty and Mölders 2006). Uncertainty analysis on soil physical parameters showed that despite high uncertainty of these parameters their impact on simulated soil heat fluxes and soil temperature is within the range of long-term measurement errors. However, they cause huge errors during freezing and thawing, i.e. along the active layer-frozen ground interface (Mölders et al. 2005). Uncertainty in plant physiolgical parameters also were found to impact surface fluxes Mölders (2005). Note that uncertainty in snow parameter also causes strong impact on fluxes (Yanchilina and Mölders 2006).
Comparison of CCSM3.0 simulated soil temperature climatologies with gridded soil temperature climatologies derived for Russia shows some discrepancies. These discrepancies can be attributed to the lower boundary condition of CCSM's soil model and discrepancies in simulated and observed cloudiness (PaiMazumder et al. 2007).
Current activities: Uncertainty caused by observations is investigated. First simulations to examine the impact of changed land-cover were performed and are currently analyzed.
Personnel: Nicole Mölders, Debasish PaiMazumder
Sponsor: NSF IARC cooperative agreement
Mölders, N., Haferkorn, U., Döring, J., Kramm, G., 2003a. Long-term numerical investigations on the water budget quantities predicted by the hydro-thermodynamic soil vegetation scheme (HTSVS) – Part I: Description of the model and impact of long-wave radiation, roots, snow, and soil frost. Meteorol. Atmos. Phys. , 84: 115-135.
Mölders, N., Haferkorn, U., Döring, J., Kramm, G., 2003b. Long-term numerical investigations on the water budget quantities predicted by the hydro-thermodynamic soil vegetation scheme (HTSVS) – Part II: Evaluation, sensitivity, and uncertainty. Meteorol. Atmos. Phys. , 84 : 137-156.
Mölders, N., Walsh, J.E., 2004. Atmospheric response to soil-frost and snow in Alaska in March. Theor. Appl. Climatol ., 77 : 77-105.
Mölders, N., 2005. Plant and soil parameter caused uncertainty of predicted surface fluxes. Mon. Wea. Rev. , 133 : 3498-3516.
Mölders, N., Jankov, M., Kramm, G. 2005. Application of Gaussian error propagation principles for theoretical assessment of model uncertainty in simulated soil processes caused by thermal and hydraulic parameters. J. Hydrometeorol ., 6 : 1045-1062.
Mölders, N., Romanovsky, V.E., 2006. Long-term evaluation of the Hydro-Thermodynamic Soil-Vegetation Scheme's frozen ground/permafrost component using observations at Barrow, Alaska . J. Geophys. Res ., 111 : D04105, doi:10.1029/2005JD005957.
Mölders, N., Luijting, H., Sassen, K., 2007. Use of Atmospheric Radiation Measurements program data from Barrow, Alaska , for evaluation and development of snow albedo parameterizations. Meteor. Atmos. Phys . (in press)
Narapusetty, B., Mölders, N., 2005. Evaluation of snow depth and soil temperature predicted by the Hydro-Thermodynamic Soil Vegetation Scheme (HTSVS) coupled with the PennState/NCAR Mesoscale Meteorological Model (MM5). J. Appl. Meteor ., 44 : 1827-1843.
Narapusetty, B., Mölders, N., 2006. Evaluation of the soil module of HTSVS by observations and a theoretically advanced numerical scheme. Mon. Wea. Rev ., 134 : 2927-2942.
PaiMazumder, D., Miller, J., Li, Z., Walsh, J.E., Etringer, A., McCreight, J., Zhang, T., Mölders, N., 2007. Evaluation of Community Climate System Model soil temperatures using observations from Russia (in press)