Seasonal water table depth (WTD) measurements from a Mobile Instrumented System Platform (MISP) grid, Atqasuk, Alaska, 2017

Water table depth (WTD) measurements were taken along the Mobile Instrumented System Platform (MISP) grid in Atqasuk, Alaska during the summer of 2017. The MISP grid is situated about 50 meters to the south of the International Tundra Experiment (ITEX) dry site. If a uniform representation of the water table within each plot was visible, then a WTD tube was placed there to measure the change in water table throughout the season. For instance if the plot was half saturated and half dry, then that plot was skipped and no tube was placed there. The exact location of WTD tubes are as follows: Between meters 0-1, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20, 21-22, 23-24, 25-26, 32-33, 34-35, 36-37, 38-39, 40-41, 42-43, 44-45, 46-47 and 48-49. A total of 22 WTD tubes were installed into the MISP grid in Atqasuk. Measurements were made once a week during the summer snow free period between mid June and mid August. WTD was calculated as the difference between the depth (centimeter) of the water table above or below the measuring tube (- Values = water above tube, + Values= water level below the height of the tube) and the height of the top of the measuring tube above the ground level. Measurements were not made (NA in data sheet) if there was persistent snow cover, interference or disturbance from other experimental infrastructure, or if water table depth tubes were dry to the upper surface of the permafrost.

2017年夏季，在阿拉斯加州阿特夸斯克（Atqasuk）的移动监测系统平台（Mobile Instrumented System Platform, MISP）网格沿线开展了地下水位埋深（Water table depth, WTD）测量工作。该MISP网格位于国际冻原实验（International Tundra Experiment, ITEX）干旱样地以南约50米处。若某样地内地下水位分布均匀、可被统一表征，则在此处布设地下水位监测管以监测整个生长季内地下水位的变化。例如，若样地内一半区域处于饱和状态、另一半区域干燥，则跳过该样地，不布设监测管。地下水位监测管的精确布设位置如下：0-1米、3-4米、5-6米、7-8米、9-10米、11-12米、13-14米、15-16米、17-18米、19-20米、21-22米、23-24米、25-26米、32-33米、34-35米、36-37米、38-39米、40-41米、42-43米、44-45米、46-47米以及48-49米区间。本次研究共计在阿特夸斯克的MISP网格中布设22根地下水位监测管。测量工作于夏季无雪期（6月中旬至8月中旬）每周开展一次。地下水位埋深的计算方式为：以测量管顶部距地面的高度为基准，地下水位相对于测量管的埋深（单位：厘米；负值代表水位高于测量管，正值代表水位低于测量管顶部高度）与该基准高度的差值。若存在持续积雪、其他实验设施造成的干扰或破坏，或地下水位监测管干燥至永久冻土层上表面，则未开展测量（数据表中记为NA）。