Thaw depth measurements from the Circumpolar Active Layer Monitoring (CALM) project for site 'Council Grid' (U27), Alaska Seward Peninsula, United States (Alaska) from 1999-2018

The primary goal of the Circumpolar Active Layer Monitoring (CALM) program is to observe the response of the active layer and near-surface permafrost to climate change over long (multi-decadal) time scales. The CALM observational network, established in the 1990s, observes the long-term response of the active layer and near-surface permafrost to changes and variations in climate at more than 200 sites in both hemispheres. CALM currently has participants from 15 countries. Majority of sites measure active-layer thickness on grids ranging from 1 hecatre to 1 square kilometer, and observe soil temperatures. Most sites in the CALM network are located in Arctic and Subarctic lowlands. Southern Hemisphere component (CALM-South) is being organized and currently includes sites in Antarctic and South America. The broader impacts of this project are derived from the hypothesis that widespread, systematic changes in the thickness of the active layer could have profound effects on the flux of greenhouse gases, on the human infrastructure in cold regions, and on landscape processes. It is therefore critical that observational and analytical procedures continue over decadal periods to assess trends and detect cumulative, long-term changes. The CALM program began in 1991. It was initially affiliated with the International Tundra Experiment and has been supported independently and continuously since 1998 through grants from the United States National Science Foundation (NSF). CALM is funded by the NSF Award 1304555 (Polar Programs). This dataset and metadata record was automatically generated from a web crawl of the original project page https://www2.gwu.edu/~calm/data/north.htm at the request of project coordinators. More information about this site and others in the project can be found at https://www2.gwu.edu/~calm/data/north.htm and also http://gtnpdatabase.org/activelayers.

环极活动层监测计划（Circumpolar Active Layer Monitoring, CALM）的核心目标是在长期（multi-decadal，数十年）时间尺度上，观测活动层（active layer）与近地表多年冻土（near-surface permafrost）对气候变化的响应。CALM观测网络于20世纪90年代建立，在南北半球的200多个站点观测活动层与近地表多年冻土对气候变率及变化的长期响应。目前，CALM计划的参与方来自15个国家。大多数站点在1公顷至1平方公里的网格区域内测量活动层厚度，并观测土壤温度。CALM网络的大多数站点位于北极（Arctic）及亚北极（Subarctic）低地。南半球分支（CALM-South）正在组织中，目前包含南极洲（Antarctic）及南美洲（South America）的站点。本项目的广泛影响源于以下假设：活动层厚度的广泛系统性变化可能对温室气体通量、寒冷地区的人类基础设施及景观过程产生深远影响。因此，持续数十年开展观测与分析工作以评估趋势并检测累积性长期变化至关重要。CALM计划始于1991年，最初隶属于国际冻土实验（International Tundra Experiment），自1998年起通过美国国家科学基金会（United States National Science Foundation, NSF）的资助独立且持续运行。CALM由NSF极地项目（Polar Programs）奖项1304555资助。本数据集及元数据记录是应项目协调员要求，通过网络爬取原始项目页面（https://www2.gwu.edu/~calm/data/north.htm）自动生成的。有关本站点及项目中其他站点的更多信息，可访问https://www2.gwu.edu/~calm/data/north.htm及http://gtnpdatabase.org/activelayers。