期刊
WATER RESOURCES RESEARCH
卷 52, 期 3, 页码 1591-1606出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2015WR017571
关键词
permafrost; groundwater; numerical modeling; advective heat transfer
资金
- Swedish Geological Survey (SGU) [60-1626/2009, 362-1593/2013]
- Helge Ax:son Johnsons Stiftelse
- Goran Gustafssons Stiftelse
- Bolin Center for Climate Research
- Swedish Society for Anthropology and Geography
- LANL Laboratory Directed Research and Development Project [LDRD201200068DR]
- Next-Generation Ecosystem Experiments (NGEE Arctic) project
- Office of Biological and Environmental Research in the DOE Office of Science
- Bolin Centre for Climate Research
- Goran Gustafsson Foundation for Nature and Environment in Lapland
- Foundation Lars Hiertas Minne
- Ahlmann Foundation
- Foundation Kungstenen
- Lagrelius Foundation
- Albert and Maria Bergstrom Foundation
- Sandstrom Foundation
- Foundation Rhodins Minne
- Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning [214 - 2014-562]
Modeling and observation of ground temperature dynamics are the main tools for understanding current permafrost thermal regimes and projecting future thaw. Until recently, most studies on permafrost have focused on vertical ground heat fluxes. Groundwater can transport heat in both lateral and vertical directions but its influence on ground temperatures at local scales in permafrost environments is not well understood. In this study we combine field observations from a subarctic fen in the sporadic permafrost zone with numerical simulations of coupled water and thermal fluxes. At the Tavvavuoma study site in northern Sweden, ground temperature profiles and groundwater levels were observed in boreholes. These observations were used to set up one- and two-dimensional simulations down to 2 m depth across a gradient of permafrost conditions within and surrounding the fen. Two-dimensional scenarios representing the fen under various hydraulic gradients were developed to quantify the influence of groundwater flow on ground temperature. Our observations suggest that lateral groundwater flow significantly affects ground temperatures. This is corroborated by modeling results that show seasonal ground ice melts 1 month earlier when a lateral groundwater flux is present. Further, although the thermal regime may be dominated by vertically conducted heat fluxes during most of the year, isolated high groundwater flow rate events such as the spring freshet are potentially important for ground temperatures. As sporadic permafrost environments often contain substantial portions of unfrozen ground with active groundwater flow paths, knowledge of this heat transport mechanism is important for understanding permafrost dynamics in these environments.
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