Effigis (Canada)

With the increasing availability of high resolution SAR imagery like RADARSAT-2 and TerraSAR-X, it becomes interesting to investigate the potential of this type of data for urban applications. There is however a great obstacle in using SAR imagery of urban areas: the corner reflector or cardinal effect problem. It is greatly problematic when multiple images of the same scene are taken from different azimuth angle. We propose a novel framework to overcome this problem by using contextual information about road orientation and building position to correct higher than normal pixel intensity caused by corner reflectors.

A field experiment was designed to assess the effects on tree nutrition of surface application of municipal biosolids and shredded paper mulch, which have previously been reported to improve the performance of high-density apples despite wide differences in nutrient content. The experiment involved four treatments which included two levels (with or without) of two organic amendments, shredded paper mulch and Greater Vancouver Regional District (GVRD) municipal biosolids. Treatments were established over a 2 m wide strip centred on the tree row in a high-density (3700 trees ha-1) Golden Delicious (Malus × domestica Borkh.) orchard in the year of planting (1997) and maintained until 2004. GVRD-biosolids was applied at 40 t ha-1 (DW) in 1997 and 20.3 t ha-1 (DW) in 2001 potentially supplying larger amounts of all plant nutrients (N, P, K, Mg, Zn, Cu and Mn) except Ca than the paper mulch. All trees received standard commercial treatments of drip fertigation of 30 g N tree-1 yr-1 and 20 g P tree-1 in the establishment year. Leaf N concentration was unaffected by biosolids application and decreased, but not to inadequate concentrations, in 3 of 6 yr for trees grown in the high C:N ratio shredded paper mulch. This response indicates the effectiveness of drip fertigated N. Leaf K declined to inadequate concentrations by the end of the experiment, regardless of treatment, but trees in the paper mulch treatment were able to sustain higher leaf K, were more vigourous, had higher yield the first three fruiting seasons and cumulatively after 8 yr despite the low N and K content of the paper. Improved K uptake was attributed to better distribution of soil moisture beneath the mulch but for long-term sustainable production, K fertigation would have been desirable. Biosolids application often raised leaf Zn, Cu and Mn concentration but increases were modest, with concentrations of Zn insufficient to change standard commercial recommendations for annual dormant Zn applications. Key words: Leaf N, K, Zn, Cu and Mn, nutrient additions, organic amendments, vigour, yield

The present work analyzes the potential of NASA EO-1 Hyperion imaging spectrometer to characterize urban structure from summer-based cloud free data over downtown Montreal (Quebec, Canada). This spaceborne hyperspectral sensor provides Earth imagery at 30 m spatial resolution, 7.5 km swath in 220 contiguous spectral bands between 400 and 2500 nm with 10 nm spectral resolution. The investigations were carried out from a slight off-nadir imagery over Montreal (Canada) in order to respond to wireless telecommunication needs. A compiled urban material spectral library is also considered. Reduction to ground radiance (apparent reflectance) was achieved from several calibration procedures. Thereafter, well-established mapping techniques were considered to characterize urban materials, especially roofs and walls of buildings. The preliminaries results highlight the potential of spaceborne hyperspectral for urban space characterization.

In the 1998-1999 winter, the operational feasibility of using RADARSAT SAR data to estimate the spatial distribution of snow water equivalent (SWE) in a large hydroelectric complex managed by Hydro-Québec (La Grande River watershed) has been successfully demonstrated. This watershed is located in the subarctic climatic region in the north-west of the Québec province. The vegetation consists of moderately dense to open Black Spruce forests, open lands, burned lands and peat bogs. In the last few years, an original approach well adapted for this region has been developed to estimate the SWE from SAR data (ERS-1, RADARSAT). This approach is based on the fact that the snow cover characteristics influence the underlying soil temperature which influences the dielectric properties of the soil and then the recorded backscattering signal. Then, a linear relationship between the backscattering ratios of a winter image and a snow-free (fall) image, and the snowpack thermal resistance (thermal insulation properties) has been established. Consequently, the algorithm infers the SWE from the estimated thermal resistance and the measured mean density of the snowpack. This algorithm has been implemented within a MapInfo™ application that has been named EQeau. It allows mapping of the spatial distribution of the estimated SWE at the desired level (pixel, square grid, sub-watershed). During the 1998-1999 winter, EQeau has been used successfully in a pre-operational mode using calibrated Wide beam images (W1) from RADARSAT. The algorithm has given mean estimated SWE values similar to the SWE values derived from Hydro-Quebec snow transects (relative difference between 1% and 13%). Also, the SWE increase measured from January to March 1999 is clearly detected on the maps covering almost 77 000 km2. The next steps will be the evaluation of the ScanSAR images and the demonstration of the economical advantages of using RADARSAT data in a hydrological forecasting system. Copyright © 1999 John Wiley & Sons, Ltd.