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首页> 美国卫生研究院文献>Wiley-Blackwell Online Open >Evaluation of a MetOp ASCAT‐Derived Surface Soil Moisture Product in Tundra Environments
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Evaluation of a MetOp ASCAT‐Derived Surface Soil Moisture Product in Tundra Environments

机译：在苔原环境中对MetOp ASCAT衍生的表层土壤水分产品进行评估

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Satellite‐derived surface soil moisture data are available for the Arctic, but detailed validation is still lacking. Previous studies have shown low correlations between in situ and modeled data. It is hypothesized that soil temperature variations after soil thaw impact MetOp ASCAT satellite‐derived surface soil moisture (SSM) measurements in wet tundra environments, as C band backscatter is sensitive to changes in dielectric properties. We compare in situ measurements of water content within the active layer at four sites across the Arctic in Alaska (Barrow, Sagwon, Toolik) and Siberia (Tiksi), taken in the spring after thawing and in autumn prior to freezing. In addition to the long‐term measurement fields, where sensors are installed deeper in the ground, we designed a monitoring setup for measuring moisture very close to the surface in the Lena River Delta, Siberia. The volumetric water content (VWC) and soil temperature sensors were placed in the moss organic layer in order to account for the limited penetration depth of the radar signal. ASCAT SSM variations are generally very small, in line with the low variability of in situ VWC. Short‐term changes after complete thawing of the upper organic layer, however, seem to be mostly influenced by soil temperature. Correlations between SSM and in situ VWC are generally very low, or even negative. Mean standard deviation matching results in a comparably high root‐mean‐square error (on average 11%) for predictions of VWC. Further investigations and measurement networks are needed to clarify factors causing temporal variation of C band backscatter in tundra regions.
机译：北极可获得卫星来源的表层土壤湿度数据，但仍缺乏详细的验证。先前的研究表明，原位与建模数据之间的相关性较低。假设土壤融化后的温度变化会影响湿苔原环境中MetOp ASCAT卫星衍生的地面土壤水分（SSM）的测量，因为C波段反向散射对介电特性的变化敏感。我们比较了阿拉斯加（巴罗，萨格旺，Toolik）和西伯利亚（提克西）在北极的四个地点（融化后的春季和冻结前的秋季）对活动层内水分的原位测量结果。除了将传感器安装在地面较深处的长期测量领域外，我们还设计了一种监测装置，用于测量西伯利亚利纳河三角洲非常接近地表的水分。将体积水含量（VWC）和土壤温度传感器放置在苔藓有机层中，以解决雷达信号穿透深度有限的问题。 ASCAT SSM的变化通常很小，这与原位VWC的低变化性相符。上部有机层完全融化后的短期变化似乎主要受土壤温度的影响。 SSM与原位VWC之间的相关性通常非常低，甚至是负的。平均标准偏差匹配导致VWC预测的均方根误差相对较高（平均11％）。需要进一步的研究和测量网络来澄清导致苔原区域C波段反向散射随时间变化的因素。

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