Hydrotope-Based Protocol to Determine Average Soil Moisture Over Large Areas for Satellite Calibration and Validation With Results From an Observation Campaign in the Volta Basin, West Africa
Hydrotope-Based Protocol to Determine Average Soil Moisture Over Large Areas for Satellite Calibration and Validation With Results From an Observation Campaign in the Volta Basin, West Africa
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DOI：
10.1109/tgrs.2008.916638
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发表时间：
2008-05
影响因子：
8.2
通讯作者：
J. Friesen;C. Rodgers;P. Oguntunde;J. Hendrickx;N. Giesen
中科院分区：
文献类型：
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作者：
J. Friesen;C. Rodgers;P. Oguntunde;J. Hendrickx;N. Giesen
在西非，这是一个极端的水分有限的地区，土壤水分信息在水文和气象建模，以改善水资源规划和粮食安全发挥着至关重要的作用。最近和即将进行的卫星飞行任务，如SMOS和MetOp，有望对土壤湿度进行区域观测。卫星的分辨率相对较粗（>100平方公里），因此需要大规模的土壤湿度信息，以便进行校准和验证。提出了一种基于水文站的土壤水分采样方案。水文地质单元被定义为具有内部一致水文特性的景观单元。这种水位分析在以下方面有所帮助：1）通过减少整体像素方差来确保统计上可靠的验证，2）通过减少采样偏差的机会来改进地面实况的采样方案。作为一个示例应用程序，我们目前的数据从三个不同的水分制度在沃尔特盆地在干旱和潮湿的时期。结果表明，土壤水分的整体像素方差的不同程度的减少，这取决于一般的水分状况。对于不同的吸水单元之间的区别，它表明，在中等湿度条件下，不同的吸水单元之间的区别是最高的，而极端干燥或潮湿的条件下，往往有一个空间上的土壤水分分布的影响。本文证实，定义良好的吸水单位产生的像素级土壤水分平均值，可以很容易地应用的改善。
In West Africa, which is an extremely moisture-limited region, soil water information plays a vital role in hydrologic and meteorologic modeling for improved water resource planning and food security. Recent and upcoming satellite missions, such as SMOS and MetOp, hold promise for the regional observation of soil moisture. The resolution of the satellites is relatively coarse (>100 km2), which brings with it the need for large-scale soil moisture information for calibration and validation purposes. We put forward a soil moisture sampling protocol based on hydrotopes. Hydrotopes are defined as landscape units that show internally consistent hydrologic behavior. This hydrotope analysis helps in the following ways: 1) by ensuring statistically reliable validation via the reduction of the overall pixel variance and 2) by improving sampling schemes for ground truthing by reducing the chance of sampling bias. As a sample application, we present data from three locations with different moisture regimes within the Volta Basin during both dry and wet periods. Results show that different levels of reduction in the overall pixel variance of soil moisture are obtained, depending on the general moisture status. With respect to the distinction between the different hydrotope units, it is shown that under intermediate moisture conditions, the distinction between the different hydrotope units is highest, whereas extremely dry or wet conditions tend to have a homogenizing effect on the spatial soil moisture distribution. This paper confirms that well-defined hydrotope units yield an improvement at pixel-scale soil moisture averages that can easily be applied.