This project engaged several Western Alaska coastal communities to describe types and formation processes associated with near-shore sea-ice phenomena during the fall freeze-up season, in particular as relevant to coastal erosion, flooding, and shoreline protection. Commentary and indigenous and local observations were drawn from and analyzed through existing community observing programs (SIZONet and ANTHC-LEO) as well as from new interviews and meetings conducted for this project. Extensive work was performed to summarize, assess, and synthesize written and recorded observations and commentary. A primary result was identification of a range of slush-ice berm events that could be broadly categorized as “advective” or “in-situ”. The subsequent form and durability of a slush ice berm deposited on the beach is a function of beach and coastline form, on-shore winds, water level (positive or negative surge), water temperature, air temperature, and the occurrence of snow. Berms exceeding 3 m in height were noted by some community members (Shaktoolik). Large, strong berms can aid a community by blocking erosive wave action and storm surge inundation. However, berms can also impede access to the ocean, restricting hunting activities. Large unfrozen berms present a hazard to cross by residents needing to gain access to the sea. For specific dates of berm occurrences available from interviews, synoptic weather analyses were undertaken to identify associated large-scale patterns of temperature and winds. Other near-shore ice occurrences include wind-driven piling of sea-ice against the shore. This can also prevent marine access; such an event, lasting several weeks during prime hunting season, occurred in May 2013 (Gambell). For purposes of translating this work into an operational setting, discussions with NOAA were initiated. This work should form a starting point to improve forecasting of near-shore ice phenomena by providing forecasters with rules of thumb for slush ice and berm formation. Near-shore ice features vary at the local scale, potentially hampering work to improve forecasts. More work is required to track relevant aspects of ice freeze-up, clarify formation processes and provide better quantitative constraints on air temperature, storm surge, and wind-speed ranges necessary to result in the formation of these features. The observing protocol and framework developed to guide opportunistic observations in coastal communities proved to be of considerable value for tracking hazardous freeze-up/storm events. In terms of methodological insights gained, a key factor when working with communities is a willingness to take the time necessary to build relationships. Without that it can be harder to secure accurate or useful information.
