Waves and Wind off the Oregon Coast
Most waves in the ocean are generated by wind blowing across the sea surface. As the wind blows over the ocean it pushes parallel to the ocean surface as well as down onto the surface. This causes water to pile up into small waves. As wind continues to blow on these ripples, the height, length, and speed of the wave increases. There is no more energy transfer once the speed of the wave equals the speed of the wind and the wave has reached its max size. Once a wave forms, it can travel long distances, unaided by wind, as such wavy conditions may be observed in a calm and windless area. In this way, the size of waves in an area is not always associated with current wind conditions.
The data in this nugget highlight the relationships between wind speed, wave height, and wave period and how these properties vary throughout the year at the OOI Coastal Endurance Array Oregon Offshore Surface Mooring. Though there is a general relationship between wind and waves (e.g. stronger winds are often associated with larger waves), the spread in the data also showcases times where the buoy detected waves that were not generated locally (e.g. times where local winds are weaker but waves are still relatively large). Looking at the annual cycle, wind and waves are both larger during the stormy winter, and smaller during the calm summer.
Near the location of this mooring off the coast of Newport OR, an open water wave energy testing facility is in development as a partnership with Oregon State University and the Department of Energy – PacWave. It will be interesting to see the waves observed by this mooring become energy to charge your cell phone, power a microwave, or maybe even run an electric car.
Waves and wind values are plotted against each other in XY plots in order to show their relationship. Note that though there is some spread in the data, for the most part, as wind increases so do the waves. The relationship is less tight for wave period and wind, though wave period and wave height are very closely coupled.
Access Wind and Wave Data
Disclaimer: data used in this example and provided in the .csv file were downloaded from the OOI on May 14, 2020. The file format and/or contents could have changed if downloaded directly from OOI Net after this date.
Pull Data Using Python Code. Code demonstrates how to download METBK and WAVSS data from the Coastal Endurance Oregon Offshore Surface Mooring using the Machine-to-Machine (M2M) interface, downsample the METBK dataset, create quick plots, and export the data as a .csv file.
Two sets of box blots show seasonal variation in atmospheric and sea surface properties. The box limits extend from the lower to upper quartiles, with a line at the median and a diamond symbol at the mean. Whiskers extend from the box to show the range of the data and circles indicate outliers. During winter months, average wind speed only slightly increases, but the whiskers increase in length indicating that though there are calm days, windy events are more prevalent during winter months. A similar dynamic occurs in wave speed and period, where average values increase in the winter, but the more striking difference is the spread of the data.
Endurance Array Oregon Offshore Surface Mooring
Location: On the Continental Slope off the coast of Oregon in the NE Pacific
Lat/Lon: 44.3811°N, 124.956°W
Water Column Depth: 588m
Platform: Surface Buoy
Surface Wave Spectra (WAVSS-A) – attached to buoy at the sea surface
Bulk Meteorology Instrument Package (METBK-A) – attached to buoy tower 3m above sea surface
Graphics Credit: OOI Cabled Array program & the Center for Environmental Visualization, University of Washington
OOI Science Theme
Essentials of Oceanography Textbook Sections
3.2 What features exist on continental margins?
8.1 How are waves generated, and how do they move?
8.2 What characteristics do waves possess?
8.3 How do wind-generated waves develop?
8.6 Can power from waves be harnessed as a source or energy?
Next Gen Science Standard Connections
HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. These data highlight the interaction between wind and wave energy. These data can also be extended to discuss offshore renewable power-generation.
Villas Boas, A.B., et al. 2019. Integrated Observations of Global Surface Winds, Currents, and Waves: Requirements and Challenges for the Next Decade. Frontiers in Marine Science 6:425. https://doi.org/10.3389/fmars.2019.00425.
Oskamp, J.A. and T. Ozkan-Haller. 2012. Power calculations for a passively tuned point absorber wave energy converter on the Oregon coast. Renewable Energy 45:72-77. https://doi.org/10.1016/j.renene.2012.02.004.
Tillotson, K. and P.D. Komar. 1997. The Wave Climate of the Pacific Northwest (Oregon and Washington): A Comparison of Data Sources. Journal of Coastal Research 13(2):440-452. https://www.jstor.org/stable/4298639.