| Abstract | [Preface] A little more than 10 years have passed since publication of the special issue of Canadian Journal of Remote Sensing (CJRS, 2005, Vol. 31(No. 5)) commemorating the retirement of Dr. Josef
Cihlar from the Canada Centre for Remote Sensing (CCRS). Dr. Cihlar
belongs to the key group of Canadian and international scientists who pioneered the development and application of systematic time series of satellite data products for studying
the Earth system. That special issue included several articles that dealt with the long-term satellite time series. It is now the right time to assess the progress in this area by publishing the follow-up CJRS special issue specifically focusing on
the development and application of the long-term satellite data records. The overall response to the invitation for this special issue from the community was quite satisfactory. The range of contributions provided a good picture of the current
situation and sufficient information to assess progress and current trends.
Several large-scale conclusions can be drawn. The long-term optical and thermal satellite data records serve now as a key contributor for deriving the climatology of the
ocean and land surface. It is demonstrated in this issue by multidecadal analysis of the sea surface temperature (SST) and minimum snow/ice (MSI) extent over land. Several articles included in this issue used long-term data records from optical
sensors such as the Advanced Very High Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), Landsat Thematic Mapper, Enhanced Thematic Mapper, and Operational Land Image (TM/ETM+/OLI) for identifying crop types,
uncovering the vegetation-hydrology linkages, describing the changes in vegetation structure over time, and evaluating nature reserve-design efficacy in the Canadian boreal forest. The important current trend includes application of active remote
sensing systems, such as LiDAR and Synthetic Aperture Radar (SAR) for precise surface elevation mapping. The studies on radar remote sensing establish the interferometric SAR (InSAR) technology and SAR time series as standard tools for
characterization of land surface deformation rates with very high precision. The long-term data records from the Canadian RADARSAT satellites were found to be very efficient for monitoring oil seeps and spills on the sea surface. The Gravity Recovery
and Climate Experiment (GRACE) satellites have been collecting data of Earth's gravity field since March 2002. These observations are used to retrieve the signal about water storage variations. Based on all the available GRACE data of over 10 years,
the terrestrial water storage climatology for Canada's landmass has been characterized for the first time in 2 articles published in this special issue. The issue also includes a study on GRACE-based flood forecasting for cold region watersheds,
which advances the applications of space-based, time-dependent gravity measurements in cold-region hydrology.
We were very pleased to receive contributions from key Canadian government departments: Natural Resources Canada (Canada Centre for
Remote Sensing, Geological Survey Canada, Canadian Forestry Service), Environment and Climate Change Canada (Canadian Ice Service, National Hydrology Research Centre), Fishery and Oceans Canada, Agriculture and Agri-Food Canada, as well as several
Canadian and international universities (University of British Columbia, University of Victoria, University of Saskatchewan, Yale University). Several important contributions were received from the authors affiliated with international research
organizations in Brazil, China, Switzerland, and the United States of America.
We would like to thank all authors, reviewers, and Professor Nicholas Coops, Editor-in-Chief of the Canadian Journal of Remote Sensing, for providing the opportunity to
be guest editors for this special issue of CJRS. |