Soil Moisture and Hydrology Projections of the Permafrost Region: A Model Intercomparison

• Main Authors: Andresen, Christian G., Lawrence, David M., Wilson, Cathy J., McGuire, A. David, Koven, Charles, Schaefer, Kevin, Jafarov, Elchin, Peng, Shushi, Chen, Xiaodong, Gouttevin, Isabelle, Burke, Eleanor, Chadburn, Sarah, Ji, Douying, Chen, Guangsheng, Hayes, Daniel, Zhang, Wenxing
• Format: Text
• Language: English
• Published: 2019
• Subjects: Arctic; permafrost
• Online Access: https://doi.org/10.5194/tc-2019-144; https://www.the-cryosphere-discuss.net/tc-2019-144/

This study investigates and compares soil moisture and hydrology projections of broadly-used land models with permafrost processes and highlights the causes and impacts of permafrost zone soil moisture projections. Climate models project warmer temperatures and increases in precipitation (P) which will intensify evapotranspiration (ET) and runoff in land models. However, this study shows that most models project a long-term drying of the surface soil (0–20 cm) for the permafrost region despite increases in the net air-surface water flux (P-ET). Drying is generally explained by infiltration of moisture to deeper soil layers as the active layer deepens or permafrost thaws completely. Although most models agree on drying, the projections vary strongly in magnitude and spatial pattern. Land-models tend to agree with the decadal runoff trends but underestimate runoff volume when compared to gauge data across the major Arctic river basins, potentially indicating model structural limitations. In general, current generation land models lack representation of important landscape processes that drive uncertainty of the future hydrological state of the Arctic, and ultimately limits our capability to predict associated land-atmosphere biogeochemical processes across spatial and temporal scales.