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首页> 外文期刊>Geomorphology >Spatial and temporal variability of ground surface temperature and active layer thickness at the margin of maritime Antarctica, Signy Island
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Spatial and temporal variability of ground surface temperature and active layer thickness at the margin of maritime Antarctica, Signy Island

机译：西尼岛海域南极边缘地表温度和活动层厚度的时空变化

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摘要

A CALM grid with a data logger system to monitor the active layer thermal regime was established on Signy Island (60°43'S, 45°38'W at 80 m a.s.l.) in December 2005. The active layer at each of the 36 nodes of the grid was monitored measuring the ground temperature at least at 4 different depths between 0.02 and 0.4 m at the end of the summer season. In addition, within the grid, we selected four sites closely spaced (in a ray of 25 m) three of which with the same topographical characteristics (north facing aspect) but different vegetation coverage (one bare ground, BG1 and two sites with different vegetation: Andreaea sp. and Sanionia uncinata) and the fourth (BG2) it is as BG1 a bare ground but with south facing aspect. In particular, 4 thermistors were located at depths of 0.02, 0.3, 0.6, and 0.9 m at BG2 and at the Andreaea sp site, 9 thermistors at 0.02,0.3,0.6,1,1.2,1.4,1.6,2, and 2.5 m at BG1 and at 0.02 and 0.6 m of depth at Sanionia site. Generally, with the same aspect, a thick vegetation cover (as in Sanionia site) provides a greater insulative effect than a thinner vegetation cover (as in Andreaea site) or bare ground (BG1) because vegetation both shades and insulates the ground resulting in a reduction in summer heat flux.Ground Surface Temperature (GST) was colder and more buffered in spring and summer under the vegetated ground than in BG1, although the coldest GST and lowest Thawing Degree Days (TDD) were recorded at BG2 and related to its southern aspect. Our data confirm that air temperature is the main driver of GST, as already reported both in the Arctic and Antarctic. We also found that the effect of air temperature changes seasonally, being drastically reduced in winter and, to a lesser extent, in fall and spring, when there is generally thin snow cover (<30 cm). During the summer, when snow cover is usually absent, the air temperature is the dominant driver, although incoming radiation also had an effect on the northern exposed bare ground and to a lesser extent on the vegetated and southerly exposed bare ground.The active layer ranges between 81 and 185 cm on the 4 continuously monitored sites and, considering the sites with the same aspect, it is thicker under bare ground (between 10% up to more than 100%) than under vegetated ground, confirming previous observations in the Arctic and Antarctic. However at our sites, climate forcing has no effect on the active layer thickness, enhancing the role of soil properties including the periods of high moisture content and lateral flow of water.The lack of a statistically significant regressions between GST and active layer thickness could be due to the limited study period (four years) and/or to the variation with time of changes in soil characteristics such as soil moisture, and the possible occurrence of non-conductive heat transfer processes including the lateral flow of water. Further data are required to understand the role of moisture and possible ground water circulation within the active layer to explain the unexpected strong dichotomy between the GST regime and active layer thickness.
机译：2005年12月，在Signy Island岛（60°43'S，45°38'W在80 m asl处）建立了一个带有数据记录器系统的CALM网格，以监控活动层的热状态。活动层位于36个节点的活动层在夏季结束时，至少在0.02和0.4 m之间的4个不同深度处，对电网进行监测以测量地面温度。此外，在网格中，我们选择了四个间隔很近的地方（25 m射线），其中三个具有相同的地形特征（朝北），但植被覆盖率不同（一个裸露的地面，BG1和两个具有不同植被的站点） ：Andreaea sp。和Sanionia uncinata），第四个（BG2）是BG1裸露的地面，但朝南。特别是，在BG2和Andreaea sp站点的0.02、0.3、0.6和0.9 m深度处有4个热敏电阻，在0.02、0.3、0.6、1、1.2、1.4、1.6、2和2.5 m处有9个热敏电阻。在BG1处以及Sanionia站点的0.02和0.6 m深度处通常，在相同的方面，较厚的植被覆盖层（如安德里亚地区）和裸露的地面（BG1），较厚的植被覆盖层（如在Sanionia场地）提供更好的隔热效果，因为植被既使阴影遮蔽又使地面绝缘，从而导致尽管在BG2记录到最冷的GST和最低的解冻度日（TDD）与其南部有关，但在植被覆盖的地面下，春季和夏季地表温度（GST）在春季和夏季比在BG1时更冷，并且缓冲更多。方面。我们的数据证实了气温是GST的主要驱动力，正如北极和南极已经报道的那样。我们还发现，空气温度的影响会季节性变化，在冬季通常会出现薄薄的积雪（<30 cm）时，冬季会大大降低，而在秋季和春季会大大降低。在夏季，通常没有积雪，但气温是主要的驱动因素，尽管入射辐射也对北部裸露的裸露地面和对植被和南部裸露的裸露地面影响较小。在4个连续监测的站点上，它们之间的距离在81至185厘米之间，并且考虑到具有相同长宽比的站点，在裸露的地面上（在10％至100％以上）比在植被下的地面厚，这证实了北极地区以前的观测结果。南极。然而，在我们的站点，气候强迫对活动层厚度没有影响，增强了土壤特性的作用，包括高水分含量和水的横向流动时期.GST和活动层厚度之间缺乏统计上显着的回归可能是由于有限的研究期（四年）和/或土壤特性（例如土壤水分）变化随时间的变化，以及可能发生的非传导性传热过程（包括水的侧向流动）。需要进一步的数据来了解水分和活性层内可能的地下水循环的作用，以解释GST方案与活性层厚度之间意想不到的强烈二分法。

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