Sea Surface Temperature Variability of Alaska's Northern Lagoons

Increased sea surface temperature (SST) can result in a variety of ecological, physical and biological changes to marine, near-shore and coastal ecosystems. Arctic amplification has directly impacted SST in high-latitude waters by extending the ice-free season and allowing more solar radiation to be absorbed into the oceans. Yet, high spatial resolution Arctic nearshore and lagoon SST change trends largely remain understudied with most studies to date focusing on offshore areas with relatively low spatial resolution satellite imagery. Enhanced satellite capabilities and image availability along with the emergence of online cloud computing (e.g. Google Earth Engine (GEE)), now allow for decadal time-scale SST variability to be examined at relatively high spatial scales. The objective of this study is to understand how the SST of five Beaufort Sea lagoons in northern Alaskan has varied seasonally and inter-annually over decadal time scales. The dataset of satellite images used in this study ranges from 1985 to the present and includes images from seasonally ice-free months. The images are composed of Landsat 5 (Thematic Mapper), 7 (Enhanced Thematic Mapper Plus), and 8 (Thermal Infrared Sensor) thermal top-of-atmosphere reflectance imagery that has been atmospherically corrected and pan-sharpened to a 15-meter spatial resolution. Image processing includes time-series and spatial analysis of Elson Lagoon, Simpson Lagoon, Stefansson Sound, Kaktovik Lagoon, and Jago Lagoon. Preliminary results for Elson Lagoon, near Utqiagvik, Alaska suggest seasonally averaged mean SST has increased, largely due to a marked increase in seasonally averaged minimum SST. Future work will explore the connections between SST trends and those of a range of other water-quality measures and environmental change observations in the coastal zone.