Global patterns of shallow groundwater temperatures
Global patterns of shallow groundwater temperatures
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DOI：
10.1088/1748-9326/aa5fb0
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发表时间：
2017-03-01
影响因子：
6.7
通讯作者：
Blum, Philipp
中科院分区：
文献类型：
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作者：
Benz, Susanne A.;Bayer, Peter;Blum, Philipp
在我们脚下仅几米处，浅层含水层是可持续能源的来源，并提供淡水储存和生态栖息地。所有这些方面都受到地下热状况的严重影响。然而，由于含水层的可达性有限，温度测量很少。最常见的是，浅层地下水温度是通过在年平均地表气温上增加一个偏移量来近似计算的。然而，这个偏移量的值并没有很好的定义，通常是任意设置的，而且很少验证。在这里，我们建议使用卫星获得的陆地表面温度，而不是表面空气温度。对29个国家的2548个测点进行了汇编，揭示了浅层地下水温度与地表温度之间偏移的特征趋势。在这里，它表明，蒸散量和积雪覆盖的影响，这种抵消全球范围内，通过潜热流和绝缘。仅考虑这两个过程，全球浅层地下水温度估计的分辨率约为1公里x1公里。当这些估计的地下水温度与实测的一个系数为0.95和均方根误差为1.4 K的确定比较。
Only meters below our feet, shallow aquifers serve as sustainable energy source and provide freshwater storage and ecological habitats. All of these aspects are crucially impacted by the thermal regime of the subsurface. Due to the limited accessibility of aquifers however, temperature measurements are scarce. Most commonly, shallow groundwater temperatures are approximated by adding an offset to annual mean surface air temperatures. Yet, the value of this offset is not well defined, often arbitrarily set, and rarely validated. Here, we propose the usage of satellite-derived land surface temperatures instead of surface air temperatures. 2 548 measurement points in 29 countries are compiled, revealing characteristic trends in the offset between shallow groundwater temperatures and land surface temperatures. Here it is shown that evapotranspiration and snow cover impact on this offset globally, through latent heat flow and insulation. Considering these two processes only, global shallow groundwater temperatures are estimated in a resolution of approximately 1 km x 1 km. When comparing these estimated groundwater temperatures with measured ones a coefficient of determination of 0.95 and a root mean square error of 1.4 K is found.