Mapping Arctic albedo and cryosphere from MODIS for the International Polar Year at the Canada Centre for Remote Sensing

The Moderate Resolution Imaging Spectroradiometer (MODIS) is a unique source of rich spectral information useful for many applications. It provides observations in 36 spectral bands ranging in wavelengths from 0.4um to 14.4um with a spatial resolution from 250m to 1km. The standard MODIS data processing system and products cover the basic operational needs for a number of products and applications. Implemented globally they, however, cannot always make the best use of MODIS 250m and 500m land channels required for monitoring and climate change applications according to the Global Climate Observing System (GCOS) requirements.
To address the needs of regional users, involved into International Polar Year (IPY) program, in enhanced MODIS data, especially in terms of spatial resolution, an independent technology for processing MODIS imagery has been developed at the Canada Centre for Remote Sensing (CCRS). It uses MODIS level 1B top of the atmosphere swath data as input. The system includes the following steps: 1) fusion (downscaling) of MODIS 500m land channels B3-B7 with 250m bands B1- B2 to obtain consistent 250m imagery for all seven bands B1-B7; 2) reprojection of 250m bands into standard geographic projection; 3) scene identification at 250m spatial resolution to obtain mask of clear-sky, cloud and cloud shadows; 4) compositing clear-sky pixels over 10-day intervals; 5) atmospheric correction; 6) new BRDF fitting procedure. The fusion technique is designed to work with MODIS/TERRA data due to known problems with band-to-band registration accuracy on MODIS/AQUA. The novel clear-sky compositing approach is proposed that significantly reduces impact of BRDF effect on raw composites by separation of pixels into two ranges of relative azimuth angle within 90deg-270deg and outside of this interval.
The developed method is applied to generate MODIS clear-sky land products in the Lambert Azimuthal Equal-Area (LAEA) projection for the entire Arctic circumpolar zone. It encompasses a 9,000km x 9,000 km area centered over the North Pole. Area covers Canada’s entire landmass and the surrounding oceans as well as a large portion of Eurasia. This product provides a unique resource for mapping surface properties and ice cover distribution across the Artic. We are looking to produce a 10-year time series at 10-day temporal and 250m spatial resolution in order to continue existing historical satellite records and to document the state and variability of land and sea cover over the Arctic region as a baseline for studying the impact of a changing climate. Examples of multi-year trends in ice/snow cover and albedo in Arctic zone will be presented.
This work is conducted at the Canada Centre for Remote Sensing (CCRS), Earth Sciences Sector of the Department of Natural Resources Canada as part of the Project J35 of the Program “Enhancing Resilience in a Changing Climate”. It is supported by the Canadian Space Agency under the Government Related Initiative Program (GRIP) and by the Canadian IPY program. MODIS data were acquired from the NASA Distributed Data Archive Center (DAAC) (http://ladsweb.nascom.nasa.gov/data/).