The Spatial and Temporal Variability of the Energy Balance at an Arctic Polygonal Tundra Site
Permafrost soils, which occupy by far the largest fraction of the arctic land area, are expected to be substantially affected by climate warming. The degradation of permafrost is potentially associated with climate feedback mechanisms such as greenhouse emissions and changes in the hydrological cycl...
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| Format: | Thesis |
| Language: | unknown |
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2010
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| Online Access: | https://epic.awi.de/id/eprint/25311/ https://epic.awi.de/id/eprint/25311/1/Langer_2010.pdf https://hdl.handle.net/10013/epic.38925 https://hdl.handle.net/10013/epic.38925.d001 |
| Summary: | Permafrost soils, which occupy by far the largest fraction of the arctic land area, are expected to be substantially affected by climate warming. The degradation of permafrost is potentially associated with climate feedback mechanisms such as greenhouse emissions and changes in the hydrological cycle, which could magnify future climate warming. The determination of the recent and future permafrost distribution and its thermal condition is therefore an essential issue for the prediction of future climate change. This requires the development of reliable monitoring and modeling schemes, which allow both the future predictions and the validation of the permafrost conditions. Studies of the surface energy balance can significantly contribute to the development of modeling schemes, since they directly measure the processes at the ground-atmosphere interface as they are represented in climate models. This thesis investigates the surface energy balance in a polygonal tundra landscape of the Lena River Delta, Siberia, in a series of extensive field measurements. The controlling factors of the surface energy balance are in particular the snow cover, the presence of a cloud cover and the ground thermal regime. The first two factors mainly inuence the radiation budget by reecting the largest part of the incoming short-wave radiation in spring, and by increasing the incoming long-wave radiation, respectively. The ground heat ux is found to be of remarkable importance for the surface energy balance, especially during the polar winter, when the refreezing active layer provides a strong supply of energy. In addition, the large annual temperature amplitude at the study site contributes to the strong ground heat uxes. Turbulent heat uxes are of great importance particularly during summer, when latent heat uxes consume about half of the net radiation. However, spatially distributed measurements of the turbulent heat uxes suggest distinctly different surface energy balances over scales of ten meters due to the regular pattern of ... |
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