Numerical simulation of permafrost thermal regime and talik development under shallow thaw lakes on the Alaskan Arctic Coastal Plain

Abstract

Thaw lakes are one of the most obvious manifestations of the hydrological system at work in the tundra regions of the Alaskan Arctic Coastal Plain, but the extent of the role of thaw lakes in Arctic land‐atmosphere interactions and feedback has yet to be fully understood. This study uses a two‐dimensional heat transfer model with phase change under a cylindrical coordinate system to simulate the long‐term influence of shallow thaw lakes on the thermal regime of permafrost and talik development on the Alaskan Arctic Coastal Plain. On the basis of previous studies of permafrost and thaw lakes at Barrow, Alaska, a series of simulation cases was conducted using different combinations of long‐term mean lake bottom temperature and lake depth. The simulated results indicate that shallow thaw lakes are a significant heat source to permafrost and talik. For a thaw lake with a long‐term mean lake bottom temperature of greater than 0.0°C a talik forms under the thaw lake. The maximum talik thicknesses (vertical distance from the ground surface to the permafrost surface) are 28.0, 43.0, and 53.2 m 3000 years after the formation of a shallow thaw lake with long‐term mean lake bottom temperatures of 1.0°, 2.0°, and 3.0°C, respectively. Talik development rate is very high in the first several years after a thaw lake formation and decreases gradually with time. No talik forms below a thaw lake with a long‐term mean lake bottom temperature equal to or lower than 0.0°C, but the temperature of permafrost below the thaw lake increases with time. Three thousand years after the formation of a thaw lake with a long‐term mean lake bottom temperature of greater than or equal to −2.0°C, ground temperature increases of more than 0.5°C occur as far as 300 m from the lake shore and as deep as about 400 m below the ground surface. It is concluded that variation of long‐term mean lake bottom temperature has a significant influence on permafrost thermal regime and talik development. Continued monitoring for thaw lake bottom temperature and ground temperature under shallow thaw lakes is needed to further improve the simulation.