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

Water table depth (WTD) measurements were taken along the Mobile Instrumented System Platform (MISP) grid in Barrow, Alaska during the summer of 2017. The MISP grid is situated about 200 meters to the north east side of the International Tundra Experiment (ITEX) dry sites. 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, 2-3, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 18-19, 20-21, 24-25, 26-27, 28-29, 30-31, 32-33, 34-35, 36-37, 38-39, 42-43, 44-45, 47-48, and 49-50. A total of 22 WTD tubes were installed into the MISP grid in Barrow. 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，在阿拉斯加巴罗（Barrow）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（Water table depth, WTD）测量工作。MISP网格位于国际冻原实验（International Tundra Experiment, ITEX）干旱样地东北侧约200米处。若某样地内地下水位分布均匀、可形成统一表征，则在此处布设地下水位测量管以监测整个生长季内的地下水位变化。例如，若样地内一半区域饱和、另一半区域干燥，则跳过该样地，不布设测量管。地下水位测量管的精确布设位置如下：0-1米、2-3米、5-6米、7-8米、9-10米、11-12米、13-14米、15-16米、18-19米、20-21米、24-25米、26-27米、28-29米、30-31米、32-33米、34-35米、36-37米、38-39米、42-43米、44-45米、47-48米及49-50米区间。总计在巴罗的MISP网格内安装了22根地下水位测量管。在夏季无雪期（6月中旬至8月中旬），每周开展一次测量。地下水位深度以测量管为基准，通过地下水位与测量管管口高度的差值计算（负值代表地下水位高于管口，正值代表地下水位低于管口高度），其中测量管管口高度以地面为基准。若存在持续积雪、其他实验设施的干扰或破坏，或地下水位测量管直至冻土层上表面均处于干燥状态，则不开展测量（数据表中记为NA）。