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During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing systems and retrieval algorithms for satellite measurements facilitated development of a snapshot of current cryospheric conditions, providing a baseline against which future change can be assessed. Key findings include: 1. surface air temperatures across the Canadian Arctic exhibit a warming trend in all seasons over the past 40 years. A consistent pan-cryospheric response to these warming temperatures is evident through the analysis of multi-decadal datasets; 2. in recent years (including the IPY period) a higher rate of change was observed compared to previous decades including warming permafrost, reduction in snow cover extent and duration, reduction in summer sea ice extent, increased mass loss from glaciers, and thinning and break-up of the remaining Canadian ice shelves. These changes illustrate both a reduction in the spatial extent and mass of the cryosphere and an increase in the temporal persistence of melt related parameters. The observed changes in the cryosphere have important implications for human activity including the close ties of northerners to the land, access to northern regions for natural resource development, and the integrity of northern infrastructure.

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Recent land cover changes in the Umiujaq region of northern Québec, Canada, have been quantified in order to estimate changes in the extent of discontinuous permafrost that strongly affect the forest-tundra ecotone. Changes in the areas covered by different vegetation types, thermokarst lakes and degradation of lithalsas have been investigated over an area of 60 km 2 , extending from widespread discontinuous permafrost in the north to areas of scattered permafrost in the south, and from Hudson Bay in the west to the Lac Guillaume-Delisle graben 10 km further east. We used high-resolution remote sensing images (QuickBird 2004, GeoEye 2009) and four Landsat scenes (1986, 1990, 2001, 2008)

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24Near-real-time flood maps are essential to organize and coordinate emergency services' 25 response actions during flooding events. Thanks to its capacity to acquire synoptic and detailed 26 data during day and night, and in all weather conditions, Synthetic Aperture Radar (SAR) 27 satellite remote sensing is considered one of the best tools for the acquisition of flood mapping 28 information. However, specific factors contributing to SAR backscatter in urban environments, 29 such as shadow and layover effects, and the presence of water surface-like radar response 30 areas, complicate the detection of flood water pixels. This paper describes an approach for 31 near-real-time flood mapping in urban and rural areas. The innovative aspect of the approach is 32 its reliance on the combined use of very-high-resolution SAR satellite imagery (C-Band, HH 33 polarization) and hydraulic data, specifically flood return period data estimated for each point of 34 the floodplain. This approach was tested and evaluated using two case studies of the 2011 35Richelieu River flood (Canada) observed by the very-high-resolution RADARSAT-2 sensor. In 36 both case studies, the algorithm proved capable of detecting flooding in urban areas with good 37 accuracy, identifying approximately 87% of flooded pixels correctly. The associated false 38 negative and false positive rates are approximately 14%. In rural areas, 97% of flooded pixels 39 were correctly identified, with false negative rates close to 3% and false positive rates between 40 3% and 35%. These results highlight the capacity of flood return period data to overcome 41 limitations associated with SAR-based flood detection in urban environments, and the relevance 42 of their use in combination with SAR C-band imagery for precise flood extent mapping in urban 43 and rural environments in a crisis management context. 44 45 Keywords: Flood mapping; Synthetic Aperture Radar, C-Band; Flood return period 46 47Simple hydraulic considerations have also been used in several image-processing algorithms to 96 guide the detection of flooded pixels in urban and rural areas (see Pierdicca et al., 2008 ; 97 Pulvirenti et al., 2011 ;Mason et al., 2012. In this approach, 98 information from surface elevation data, which have the advantage of being available for most 99 rivers worldwide, is exploited. However, such algorithms restrict the integration of hydraulic 100 considerations to simple elevation and proximity analysis. To our knowledge, no example can 101 be found in the recent literature of the explicit integration of hydraulic data within SAR image-102 processing algorithms for flood detection in urban and rural areas. Such data, which could 103 include information about a river's flooding pattern or the specific hydraulic characteristics of a 104 floodplain, could be of great use in areas where SAR-based flood detection remains a 105 challenge. 106Therefore, the objective of the present study is to demonstrate how a combination of very high 107 resolution SAR imagery and hydraulic da...

The Arctic and sub-Arctic environments have seen a rapid growth of shrub vegetation at the expense of the Arctic tundra in recent decades. In order to develop better tools to assess and understand this phenomenon, the sensitivity of multi-polarized SAR backscattering at C and X band to shrub density and height is studied under various conditions. RADARSAT-2 and TerraSAR-X images were acquired from November 2011 to March 2012 over the Umiujaq community in northern Quebec (56.55 • N, 76.55and compared to in situ measurements of shrub vegetation density and height collected during the summer of 2009. The results show that σ 0 is sensitive to changes in shrub coverage up to 20% and is sensitive to changes in shrub height up to around 1 m. The cross-polarized backscattering (σ 0 HV ) displays the best sensitivity to both shrub height and density, and RADARSAT-2 is more sensitive to shrub height, as TerraSAR-X tends to saturate more rapidly with increasing volume scattering from the shrub branches. These results demonstrate that SAR data could provide essential information, not only on Remote Sens. 2015, 7 9411 the spatial expansion of shrub vegetation, but also on its vertical growth, especially at early stages of colonization.