CGRG Bibliography of Canadian Geomorphology
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Author : Blanchette, J-P.; Sushama, L.; Laprise, R.; Allard, M.; Gigučre, M.; Harvey, R.; and Verseghy, D.
Date : 2010.
Title : Future climate in Canada: A regional modelling approach for permafrost soils.
Publication : CMOS-CGU Ottawa 2010. 44th Annual CMOS Congress, 36th Annual Scientific Meeting of CGU, 3rd Joint CMOS-CGU Congress. May 31-June 4, 2010. Ottawa, Ontario.
Issue :
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Abstract
One of the biggest changes expected by climate modellers for northern climate lies in the response of permafrost soils to climate change. It is well accepted now that permafrost will experience a general degradation following the rise of air temperature during the 21st century, and, in doing so, it will affect not only the climate via positive feedbacks but also local populations and infrastructures. However, the actual challenge is to simulate these predicted changes of thermal and hydraulic soil states as best as possible with the tools currently available. This is why the new version of the Canadian Land Surface Scheme (CLASS) has been implemented in the Canadian Regional Climate Model (CRCM). The operational version of CLASS currently used in the CRCM has two major problems for accurate soil modelling simulations, particularly for permafrost areas. First, the shallow soil depth configuration (4.1m) leads to unrealistic energy dynamics caused by the zero heat flux condition at the soil bottom boundary. Second, the three-layer soil configuration (0.1, 0.25 and 3.75m) completely prevents the possibility of resolving the active-layer thickness (ALT) in permafrost regions. These issues - among others - have been addressed in the new version of CLASS: it has a deeper soil configuration (e.g., 100m) and a flexible layering scheme with multiple soil layers (e.g., 20 layers). Moreover, organic matter parameterization has been added to soil properties, which means that it is now possible to represent peat in the top-soil layers. Preliminary results based on coupled CLASS-CRCM simulations for present and future climates will be shown. Sensibility analyses on different configurations of the land surface scheme will also be discussed and compared with offline simulation tendencies. Offline simulations have already shown that having a deeper soil configuration and organic matter parameterization delay the near-surface permafrost degradation.
Bibliography of Canadian Geomorphology