The Role of Permafrost in Eurasian Land-Atmosphere Interactions

Permafrost is an important indicator of climate change that affects, e.g., ecosystems, hydrology, and infrastructure in cold regions. Interactions between the surface and atmosphere in permafrost regions are complex and vary seasonally due to the contrasting energy and moisture conditions of frozen versus unfrozen ground. Differences in surface-atmosphere connections have been documented between permafrost types, with significantly increased moisture feedbacks in areas of continuous Eurasian permafrost, but no such relationship in other regions. This study elucidates the processes responsible for these observed land-atmosphere feedbacks in Eurasian permafrost regions. The Weather Research and Forecasting model is used to determine the varying effects of discontinuous versus continuous permafrost on different weather scenarios. For two 72-hour periods, surface fluxes, boundary layer characteristics, and corresponding meso-to-synoptic scale meteorological features varied when comparing the two experiments: one with a saturated active layer representing continuous permafrost, and another witht1 a drier surface layer representing discontinuous permafrost. Depending on the weather regime, an increase in boundary layer moisture in response to increased latent heat fluxes over continuous permafrost increases precipitation and low-level cloudiness. The effects of changing soil conditions are evident as far aloft as 500 hPa, as a mid-level low over continuous permafrost is stronger and moves southward. Incipient moisture associated with continuous permafrost allows for different land-atmosphere interactions than over discontinuous permafrost. Continued permafrost degradation as a result of climate change may lead to increased dryness in the region, altering the surface energy balance and associated weather and climate feedbacks.