Hydrology and Earth System Sciences Soil Surface Moisture Estimation over a Semi-arid Region Using Envisat Asar Radar Data for Soil Evaporation Evaluation
Hydrology and Earth System Sciences Soil Surface Moisture Estimation over a Semi-arid Region Using Envisat Asar Radar Data for Soil Evaporation Evaluation
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6.1
通讯作者：
M. Zribi;A. Chahbi;M. Shabou;Z. Lili-Chabaane;B. Duchemin;N. Baghdadi;R. Amri;A. Chehbouni
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作者：
M. Zribi;A. Chahbi;M. Shabou;Z. Lili-Chabaane;B. Duchemin;N. Baghdadi;R. Amri;A. Chehbouni
本文提出了一种利用雷达卫星测量的土壤湿度估算土壤蒸发的方法。我们首先提出了一种方法，估计和监测土壤水分在北非半干旱地区，使用ENVISAT ASAR图像，在两种类型的植被覆盖。第一个制图过程专门用于监测“非灌溉橄榄树“类土地使用地区与降雨事件有关的湿度变化。所开发的方法是基于一个简单的线性关系土壤水分和后向散射雷达信号归一化在一个参考入射角。第二个过程是建议在小麦田，由于降雨和灌溉的水分变化的分析。一个半经验模型，植被校正的水云模型的基础上，被用来从雷达信号反演土壤水分。在小麦田上进行了水分测绘，显示灌溉和非灌溉小麦覆盖之间的高度可变性。这项分析是基于一个大型数据库，包括环境卫星ASAR和同时获得的地面实况测量（湿度，植被，粗糙度），在2008-2009年植被周期。最后，提出了一种半经验的方法，以便将地表水分与土壤蒸发和气候需求之间的差异联系起来，如潜在蒸发所定义的。提出了土壤蒸发制图方法。
The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the " non-irrigated olive tree " class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness), during the 2008–2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed.