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

这项北方实地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，如导热性，以及雪的比表面积，以及这将如何反过来改变永久冻土的热状况。在气候变暖的情况下，永久冻土融化，通过释放温室气体，将对气候产生积极的反馈，这种反馈的强度在今天受到很大的限制。我们将在北极北部的两个北方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。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）。测量将包括对雪和土壤的导热性和温度垂直分布以及土壤湿度和热扩散率的永久监测。我们还将进行辐射测量，并从现有的大气测量中受益，以便我们能够充分限制地表和地面的能量预算。冬季实地考察将测量雪密度和比表面积分布，并调查所有上述变量的空间变异性。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。已经在Umiujaq的森林苔原和灌木苔原部署了两个监测站，我们将于2013年在Bylot再部署一个监测站。数据采集将持续整个项目，并希望超越，增加一个雪的层面已经丰富的数据库，由中心d '研究北欧拉瓦尔。我们将努力让当地社区参与这项工作，特别是让他们参与对雪密度和温度分布的定期测量。

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.