Assessing Seasonal Lake Dynamics in Arctic Alaska: Preliminary Results

Lakes on the coastal plain of arctic Alaska have developed atop continuous permafrost. Recent research suggests that lake levels, rates of bank erosion and drainage, and depth of the thaw bulb in sediments beneath the lake may increase in response to a warmer and wetter climate. Assessment of lake dynamics entails separating seasonal and interannual fluctuations from the long-term response. A program to study lake dynamics was initiated in 2008 and includes: (1) analysis of both long-term lake changes and seasonal/ interannual fluctuations using high-resolution satellite imagery and aerial photographs, (2) repeated high- resolution mapping of shoreline configuration in spring and late summer using differential GPS combined with water level sensors, (3) conducting bathymetric surveys to determine basin shape and water volume, (4) evaluating the relation between wind vectors and surface water currents with real-time satellite networked GPS-enabled floats and a wide-area wireless network, and (5) quantifying the energy and water balance on a representative lake using data collected from a fully instrumented buoy. Lake basins surveyed near Barrow, Alaska have a maximum depth of 1.5-3.0 m and are characterized by a steep drop-off near the shore and very gradual deepening toward the center. Seasonal shoreline fluctuations are observed in most lakes, with the maximum effect noted in low-lying regions of the lake margin as the water level gradually falls through summer. Preliminary analysis of the lake energy and water balance is presented, including measurements of incoming and outgoing radiation, latent and sensible heat flux, and associated lake temperature and atmospheric parameters. In subsequent years, measurements will be made on lakes further inland where the surficial geology and climate differs from the coastal environment.