University of Washington (UW) oceanographers have conducted almost four decades of observational research and data collection on coastal resources relevant to Marine Spatial Planning (MSP) on the outer Washington coast and in Washington’s coastal estuaries, including those related to renewable energy, cable installation, and ecosystem habitat evaluation. Recent UW research developed a cutting-edge numerical model of currents, water conditions, and the ecosystem for the coastal Washington region, which also provides relevant data for MSP.
The University of Washington team was tasked with ensuring that the MSP process for Washington State incorporated the latest understanding of both the static features of the ocean and the dynamic, time-variable processes that define zones of greatest primary productivity; for example, how critical habitats change with seasons. To that end, the UW oceanography observational datasets and models provide information on the monthly, seasonal, and decadal changes that characterize coastal ocean processes and the degree of variability that can be expected.
Below are animated maps of various products derived from the UW oceanography models with descriptions to help the user interpret the meaning of each output.
Read the final report for more information.
Table of Contents
- Bottom Oxygen
- Hypoxia Indices
- Chlorophyll
- Current Speed
- River Influence Index
- Surface Salinity
- Bottom Temperature
- Sea Surface Temperature
- References
Bottom Oxygen
Metric: seasonal average (top), seasonal minimum (bottomHp)
Range: 0-13 mg/l. Hypoxia is defined as less than 2 mg/l.
Analysis Time Period: 2005-2006
The seasonal average and minimum cycles of bottom oxygen on the continental shelf and slope are included for context. The images give an indication of hypoxia and the available ocean nutrients on the shelf of the Washington coast. Bottom oxygen is closely related to the coastal upwelling conditions along the shelf.
Hypoxia Indices
Metric: seasonal average
Analysis Time Period: 2005-2006
- Hypoxia Frequency Index
Measures the frequency of occurrences of hypoxic (low oxygen) for long in oxygen-depleted environments. Prolonged periods of hypoxia result in extensive “dead zones”, where the marine animals must migrate away from the oxygen-free areas or else die of suffocation. The hypoxia frequency index can be coupled with the related hypoxia intensity index that provides information on the severity of seasonal hypoxic conditions.
- Hypoxia Intensity Index
Measures the intensity of seasonally averaged hypoxic (low oxygen) conditions from mild to severe. It can be coupled with the hypoxia frequency index that provides related information about how frequently the hypoxic conditions occur.
Hypoxia Findings
The indexes about are used together to observe correlations and differences in oceanographic conditions along the Washington coast. For example, the indexes on intensity and frequency show that the inner shelf north of Grays Harbor experiences infrequent but intense hypoxia events, while the outer shelf at the same latitude experiences frequent but mild events. This information can be used to characterize conditional changes seasonally and annually.
Chlorophyll
Metric: 0-300 mg/meters squared
Analysis Time Period: 2005-2006
Plankton productivity shows the general food and prey availability through the seasonal cycles of phytoplankton and zooplankton productivity. Here, the average chlorophyll concentration serves as a proxy for plankton productivity at all depths of the water column. All of the standing stocks and rates of productivity are well correlated on the time and space scales relevant to planning activities, and that variability is high everywhere that productivity is high. Chlorophyll concentration is the simplest and best metric of overall productivity relevant to commercial fisheries and aquaculture.
Current Speed
Metric: maximum and average current speed at 10 meters above the seafloor
Analysis Time Period: 2005
The average (left) and maximum (right) current speed 10 meters above the bottom is shown, based on hourly values throughout 2005. The maps below represent the combination of tidal currents with wind-driven and other weather-event-scale variations in the circulation. These parameters are important to choosing best locations for alternative energy sites.
River Influence Index
Metric: percentage of time where surface salinity is less than 31.5 practical salinity units (PSU)
Analysis Time Period: April 2004-December 2006
These maps show the seasonally averaged patterns of salt and fresh water mixing along the Pacific Northwest coast. 0% indicates a completely seawater-dominated (salinity > 31.5 PSU) area, and 100% suggests a fresh (river) water-controlled area. These surface water patterns are primarily due to the influences of the Columbia River and the Salish Sea, and are affected by seasonal snowmelt and rainwater delivered at their mouths, as well as by the prevailing upwelling conditions existing on the coastal shelf.
Surface Salinity
Metric: seasonal average
Analysis Time Period: April 2004- December 2006
Surface water salinity is the average concentration of dissolved salts in a volume of water. Here it is measured in practical salinity units (PSU) and seasonally averaged. PSU is based on the property of sea water conductivity and 1 PSU is roughly equal to 1 gram of salt per 1 kilogram of water. Seawater is generally between 30-40 PSU and river water is typically <5 PSU (with freshwater ≤ 0.5 PSU). The significant influence of the Columbia River is easy to see in these images.
Bottom Temperature
Metrics: seasonal average (top), Minimum (bottom left), and maximum temperature (bottom right) for continental shelf and slope (0-400 meter depths).
Analysis Time Period: April 2004- December 2006
These images display seasonally averaged bottom temperatures in degrees Celsius. Bottom temperature is an important parameter affecting habitats of bottom-dwelling marine species. Colder water usually indicates more nutrient-rich water.
Sea Surface Temperature
Metrics: seasonal average (top), minimum (bottom left), and maximum (bottom right) SST ranging from 0-24 degrees Celsius.
Analysis Time Period: April 2004- December 2006
The average, minimum, and maximum daily water surface temperature images display the averages temperatures for each season. The Sea Surface Temperature (SST) maps show that cold water is upwelled near the coast in the autumn and winter months, delivering relatively undiluted deep, cold, nutrient-rich water to the surface. During the spring and summer months the coastal waters are warmer. Upwelling is a key process in creating a highly productive and abundant fishing and aquaculture environment along the Pacific Northwest coast.
References
For more information, read the final report for this Marine Spatial Planning project.
The full model documentation and discussions for this work are also available in peer-reviewed literature including these published articles:
- Davis KA, Banas NS, Giddings SN, Siedlecki S, MacCready P, Lessard EJ, Kudela RM, Hickey, BM (2014). Estuary-enhanced upwelling of marine nutrients fuels coastal productivity in the U.S. Pacific Northwest. J. Geophys. Res., 119:8778-8779.
- Giddings SN, MacCready P, Hickey BM, Banas NS, Davis KA, Siedlecki SA, Trainer VL, Kudela RM, Pelland N, Connolly TP (2014) Hindcasts of harmful algal bloom transport on the Pacific Northwest coast. J. Geophys. Res., 119:2439-61.
- Siedlecki SA, Banas NS, Davis KA, Giddings SN, Hickey BM, MacCready P, Connolly TP, Geier S (2015). Seasonal and interannual oxygen variability on the Washington and Oregon continental shelves. J. Geophys. Res., 120:608-633.