Spatial Variability of Tidal Currents in Puget Sound, Washington

Tidal currents are an important factor in estuarine circulation, stratification and exchange, while also critically important to predict for safe and efficient marine navigation. Puget Sound, Washington is a dynamically complex and spatially variable estuary with strong tidal currents and significant environmental concerns including ocean acidification, hypoxia and pollutant transport. Puget Sound is also a major hub for both recreational and commercial marine navigation. Despite these facts, there have been no studies to observe the spatial variability of currents throughout the Sound in the past three decades. The NOAA NOS Center for Operational Oceanographic Products and Services is performing a large-scale currents survey that over the next two years will provide observations of currents throughout the water column at nearly 140 different locations throughout Puget Sound, the Strait of Juan de Fuca and the San Juan Islands. Here we present a spatial analysis of tidal currents covering the 48 different locations in Puget Sound that were observed in 2015. Spatial variability in tidal currents is correlated to topographic features as well as salinity and temperature profiles and time series collected at a portion of these locations. The observations and analyses presented here will result in more accurate tidal current predictions for marine navigation, as well as aid in the development of numerical hydrodynamic models which are used to better understand the many environmental issues facing the Sound.