Investigation of vegetation,snow,permafrost,climate interactions for improved predictions of the permafrost thermal regime

这项北部野外研究旨在了解不同的气候和植被类型如何影响雪和土壤的物理性质，如热导率和雪的比表面积，以及这将如何反过来改变永久冻土的热状态。在气候变暖的情况下，通过释放温室气体，永久冻土融化将对气候产生积极的反馈，而这种反馈的强度目前受到的限制很少。我们将在北部的两个地点进行雪和土壤测量，这些地点的植被范围从森林苔原到高北极的草本苔原不等。选定的地点是努纳维克的Umiujaq （56°N）和巴芬岛北部努纳武特的Bylot岛（73°N）。测量将包括永久监测雪和土壤的导热性和温度垂直剖面，以及土壤湿度和热扩散率。我们还将进行辐射测量，并从现有的大气测量中获益，这样我们将能够充分约束地表和地面的能量收支。冬季实地考察将测量雪密度和比表面积剖面，并调查上述所有变量的空间变异性。夏季实地考察将研究土壤特性及其变异性，以及植被组合及其与雪特性的关系。在Umiujaq的森林冻土带和灌木冻土带已经部署了两个站点，我们将于2013年在Bylot再部署一个站点。数据采集将贯穿整个项目，并有望超越项目，为位于拉瓦尔的Nordiques Centre d’etude保存的已经丰富的数据库增加一个新的维度。我们将尝试让当地社区参与这项工作，特别是让他们定期测量雪密度和温度剖面。

This northern field research seeks to understand how different climates and vegetation types will affect snow and soil physical properties such as thermal conductivity and, for snow, specific surface area, and how this will in turn modify the permafrost thermal regime. In a warming climate, permafrost thawing, by releasing greenhouse gases, will positively feedback on climate and the strength of this feedback is today poorly constrained. We will perform snow and soil measurements at two northern sites with vegetation ranging from forest tundra to herb tundra in the high Arctic. The selected sites are Umiujaq (56°N) in Nunavik and Bylot Island (73°N) in Nunavut, north of Baffin Island. Measurements will include permanent monitoring of snow and soil thermal conductivity and temperature vertical profiles, and soil humidity and thermal diffusivity. We will also perform radiation measurements and benefit from existing atmospheric measurements, so that we will be able to fully constrain the energy budget of the surface and of the ground. Winter field trips will measure snow density and specific surface area profiles and investigate the spatial variability of all the above variables. Summer field trips will study soil properties and their variability, as well as vegetation assemblages and their relationship to snow properties. Two stations have already been deployed in forest tundra and shrub tundra at Umiujaq and we will deploy one additional station at Bylot in 2013. Data acquisition will last throughout the project and hopefully beyond, adding a snow dimension to the already rich data base kept by Centre d'Etude Nordiques at Laval. We will attempt to involve local communities in this work, in particular by involving them in regular measurements of snow density and temperature profiles.