CGRG Bibliography of Canadian Geomorphology
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Author : Belanger, J.; and Berg, A.
Date : 2008.
Title : Design of soil moisture networks for validation of remotely sensed soil moisture observations.
Publication : 400 Years of Discovery. 2008 Annual Conference of the Canadian Association of Geographers. May 20-24, 2008. Laval University, Quebec City, Quebec.
Issue : Abstract Volume.
Page(s) : 10.
Abstract
The soil water state plays a critical role in the exchange of energy and moisture between the land surface and the atmosphere. Soil moisture also has direct impacts on flood and drought prediction, weather forecasting, and water management. Therefore, knowledge of the temporal and spatial variability of soil moisture is vital; however, present understanding is impeded by a poor understanding of the controls on soil moisture and a paucity of observations at sufficient spatial and temporal scales. Passive microwave sensors aboard current and future satellites offer promise for daily measurement at a global scale, but require validation from ground-based datasets to ensure the data are accurate. Such validation datasets must be representative of the spatial extent of a remote sensing pixel (35 x 35 km). To date, no ground-based networks have been established at scales relevant to a satellite pixel (35 x 35 km). The purpose of this research was to address this concern through the establishment of a representative validation network from ground-based measurements. The objectives employed to achieve this were to: (1) develop a network representative of the mean soil moisture within a satellite footprint; (2) evaluate individually each site within the network to determine how representative they are and their use in validation. In May 2007, a soil moisture monitoring network was installed in an agricultural region of southwestern Ontario in which 16 sites recorded soil moisture on a half-hourly time interval at depths of 5, 20 and 50 cm. Results spanning the 2007 growing season (May-November) indicate that the mean of a satellite pixel can be representatively captured from ground-based, point measurements of soil moisture, provided sites are situated so as to be representative of the controls on soil moisture. Further, it is demonstrated that there are sites which consistently reflect the mean of the network, as well as those which consistently reflect extremes of the network, regardless of season. The identification of such representative and temporally persistent sites is critical for alleviating the monetary and time constraints associated with installing soil moisture monitoring equipment. The identification of the factors responsible for making a given site representative and temporally persistent will be invaluable for developing land surface models to predict the location of sites a priori. The establishment of a representative network is not only critical for the validation of remotely sensed soil moisture observations, but also for characterizing the controls on soil moisture across time and space.
Bibliography of Canadian Geomorphology