Long‐term evaluation of the Hydro‐Thermodynamic Soil‐Vegetation Scheme's frozen ground/permafrost component using observations at Barrow, Alaska

Abstract

[1] The multi-layer frozen ground/permafrost component of the hydro-thermodynamic soil-vegetation scheme (HTSVS) was evaluated by means of permafrost observations at Barrow, Alaska. HTSVS was driven by pressure, wind, air temperature, specific humidity, snow-depth, rain, downward shortwave and long-wave radiation observations for 14 consecutive years. Observed soil temperature data are available at various times during this period. HTSVS predicts soil temperatures that are slightly too low with root mean square errors (RMSEs) of, on average, less than 3.2 K. Sensitivity studies suggest that the treatment of snow and vegetation cover may be reasons for the inaccuracy. HTSVS' original thermal conductivity parameterization provides thermal conductivity values that are too high compared to typical observations. Introducing a parameterization frequently used in the permafrost research community, which was modified for application in numerical weather prediction (NWP) and climate models and model consistency in HTSVS, improves soil temperature predictions and reduces RMSEs in some layers by up to 1 K, and on average by 0.2 K. Assuming five to ten layers for the first 2 or 3 m as is usually done in NWP and climate modeling is insufficient to capture the active layer depth, because the number and position of the grid nodes play a role. The depth of the lower boundary of the soil model and the boundary condition affect the overall performance. Consequently, under current computational possibilities, simulating permafrost and the active layer in atmospheric models requires a compromise between the degree of accuracy and affordable computational time.Citation: Mölders, N., and V. E. Romanovsky (2006), Long-term evaluation of the Hydro-Thermodynamic Soil-Vegetation Scheme's frozen ground/permafrost component using observations at Barrow, Alaska,

Using Earth’s Moon as a Testbed for Quantifying the Effect of the Terrestrial Atmosphere

“…The Crank-Nicolson scheme in combination with a Gauss-Seidel iteration procedure serve to numerical integrates this parabolic differential equation. These numerical techniques have already been used in the hydro-thermodynamic soil-vegetation scheme (HTSVS) developed by Mölders and Kramm (e.g., [54,55,58,[65][66][67]). Despite the numerical techniques was thoroughly tested and evaluated by data from field campaigns during the development of HTSVS, we tested these techniques also against the results presented in Figure 4 and Robie et al [64] and Hemingway et al [62].…”

The incorporation of an organic soil layer in the Noah-MP land surface model and its evaluation over a boreal aspen forest

“…Organic soil horizons also have relatively low thermal conductivity, relatively high heat capacity, and a relatively high fraction of plant-available water. Prior studies illustrated the importance of parameterizing organic soil horizons in LSMs for simulating soil temperature and moisture (e.g., Letts et al, 2000;Beringer et al, 2001;Mölders and Romanovsky, 2006;Nicolsky et al, 2007;Lawrence and Slater, 2008).…”

Improved modeling of permafrost dynamics in a GCM land‐surface scheme

“…Given the correct parameters, these stand-alone models are accurate and can be used for a quantitative analysis. The second approach involves simulation and prediction of permafrost dynamics within a coupled global climate model [Stendel and Christensen, 2002;Lawrence and Slater, 2005;Mölders and Romanovsky, 2006]. This approach permits the integration of potentially important interrelationships between permafrost, hydrology, and climate.…”