The aim of this project is to map and document the spatial and temporal distribution of recurring lead systems, coastal polynyas and landfast ice off the coast of northern Alaska and parts of the Russian Chukchi Sea coast and the Canadian Beaufort Sea coast. Part of the study is an extension in time of a previous Minerals Management Service (MMS) Outer Continental Shelf (OCS) study (#2005-068, MMS, Alaska OCS Region, 2005) which included analysis of data from the winter of 1993-94 through 2003-2004 along the Alaska coast between Wainwright on the Chukchi Sea and the Mackenzie River Delta in the Canadian Beaufort Sea. This work will be extended in time into 2008. The work will also cover a second study area encompassing the eastern Chukchi Sea, extending the area covered in the previous study south to the Chukchi Peninsula coast of Russia. This region includes oil and gas leases sold in 2008 for which sea-ice information is lacking. The period of analysis will be from 1993 through 2008, with a qualitative examination of older, archived data. Given dramatic reductions in Arctic summer sea ice extent since 2005 and the importance of the study region to protected marine mammals and birds lends urgency to the proposed work. The methods employed for analysis will follow those of the previous study to provide for a consistent, comprehensive assessment of landfast ice distribution and lead patterns. The extent and duration of the landfast ice in both areas will be analyzed with Radarsat Synthetic Aperture Radar (SAR) collected between 1996 and 2007. Lead distributions will be quantified from Advanced Very High Resolution Radiometer (AVHRR) data for the period between 1993 and 2008. These data will be compared to AVHRR imagery from the 1970's and 1980's. Monthly mean landfast ice edge positions and spatial statistics of lead distributions will be derived from these data for the time period of stable, closed sea-ice cover. Longer-term spatio-temporal variations in landfast ice extent and lead patterns will be assessed in the context of large-scale atmospheric and oceanic change. Because Radarsat data are not available to the investigators after April 2008, a new technique using the PALSAR radar sensor on the ALOS satellite will be tested for use in identifying the landfast ice edge. Project products and deliverables include ArcGIS grids and shapefiles of monthly landfast ice extents and lead distributions with accompanying metadata. A dedicated project web site will be set up to allow for monitoring of project progress and access deliverables as they become available.