The landscape-scale effects of coastal storms on Alaska‘s Bering Sea coast include coastal erosion, migration of spits and barrier islands, breaching of coastal lakes and lagoons, and inundation and salt-kill of vegetation. In areas experiencing moderate to large effects, changes can be mapped by analyzing trends in time series of Landsat MultiSpectral Scanner (MSS), Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery. The archive of Landsat imagery covers the time period 1972–present. Regression analysis will identify areas with significant changes in wetness and greenness across the study period. The extent of coastal erosion and other landscape change can be assessed along the entire Bering Sea coast using this approach. Hotspots of change identified by the wide coverage of the mapping proposed in this study will provide guidance on selecting areas for monitoring or for more intensive research (e.g., terrain sensitivity analysis).
ABR reviewed the extensive time series of Landsat imagery (1972–2012) covering the Bering Sea coast and Gulf of Alaska coast within the bounds of the Western Arctic LCC. The spatial and temporal coverage of Landsat data with substantial cloud-free area will be reviewed and described for the study areas. Suitable imagery from Landsat 1, 2, 3, 4, 5 and 7 will be identified.
Landsat MSS scenes are the only imagery available from the first three Landsat satellites (primarily covering the time period 1972–1982). Landsat 4 and 5 collected both MSS and TM data though in some cases only MSS data were acquired. In general, the TM data are preferred. The MSS data are coarser resolution than TM and ETM+ data with 60-m compared to 30-m pixels, and MSS data lack some of the spectral channels available with TM and ETM+. However, the MSS data are the best digital satellite imagery available for the earlier time periods. This is particularly important for some areas in western Alaska where little Landsat TM or ETM+ imagery is available prior to 1999.
During Phase II we will acquire Landsat imagery (1972–2013) and analyze coastal change for the Bering Sea and Gulf of Alaska Coast within the LCC geography (including Kodiak and Afognak Islands).