The Potential of High Resolution Soil Moisture from Active Microwave Remote Sensing for Supporting Precision Viticulture
Bauer-Marschallinger, Bernhard1; Greifeneder, Felix2; Hasenauer, Stefan2; Wagner, Wolfgang2
1Vienna Technical University, AUSTRIA; 2Vienna University of Technology, AUSTRIA
Soil moisture is an important environmental variable with significant impact on hydrologic and agricultural processes on global as well as local scales. Knowledge of the spatial and temporal variation of Surface Soil Moisture (SSM) is crucial to water budget analyses and agricultural water management activities. Spaceborne microwave remote sensing has shown its capability of measuring SSM in a global manner with satisfying accuracy and temporal sampling and thus enables operational SSM observations already. However, present SSM monitoring systems based on scatterometers, e.g. MetOp ASCAT, provide data at a rather coarse spatial resolution of tens of kilometres and thus are not able to capture small scale phenomena. Disciplines like precision viticulture, meaning the technology-driven assessment and management of vineyard conditions, demand information on SSM at hectometric scale, meeting the dimension of individual vineyards. Here, potential of SSM derived from Synthetic Aperture Radar (SAR) data is identified. Therefore, this study aims to transform a change detection method that retrieves SSM from Envisat ASAR Global Monitoring Mode data at 1 km to a retrieval of SSM at 150 m from ASAR Wide Swath Mode. This is done in the perspective of ESA’s upcoming earth observation campaign, including the Sentinel-1 satellites carrying a C-band SAR system as continuation of ASAR. The increased complexity of hectometric observations demands to refine the model, involving classification by land cover and radar backscatter. Furthermore, a fusion of ASCAT and ASAR data is pursued for generation of a SSM product benefitting from the high temporal sampling of ASCAT and fine spatial resolution of ASAR. This is accomplished by matching individual time series of SSM and profile soil moisture (Soil Water Index, SWI) from ASCAT and ASAR each, and is carried out over wine regions in Italy, Portugal and France.