Improve and Evaluate the Common Land Model at Samoylov Permafrost Site

Circumpolar permafrost in Northern hemisphere contains substantial amount of organic matters. The soil organic matters influence the thermal and hydraulic properties in most permafrost regions, insulating the soil especially in non-snow season. Once thawed, released carbon would enhance the global green-house effect through permafrost carbon feedback. Land surface model is an important tool to study how permafrost responds to climate change. The way hydrothermal conditions are represented in models determines the exchanges of heat and water between land and air as well as among the soil layers. Therefore, it's of great scientific significance to improve the scheme of soil hydrothermal parameterization for simulating soil moisture content and soil temperature.

Samoylov island in Lena river delta, northern Siberia is a typical region of high latitude permafrost containing large amount of frozen soil organic carbon. Observations and measurements of soil and atmosphere have been recorded for more than 16 years at this site. Former studies using data from Samoylov site showed significant improvement of soil temperature simulation by incorporating moss layer, soil organic matter, enhanced snow representation and some other factors. This study aims at improving the Common Land Model's simulation at Samoylov site by explicitly considering moss layer and better representing soil organic matters' properties. Results show that CoLM can reproduce the thermal state and variation of soil temperature at Samoylov site. While poorly simulated soil water content suggests lateral waterflow caused by geomorphic heterogeneity might exert large effects on soil moisture at this site. This study would facilitate further researches of Samoylov site's permafrost carbon dynamics.