Changing Trends in Wave Heights in the U.S. Mid-Atlantic Region

• Main Author: Lane, Hillary
• Format: Thesis
• Language: unknown
• Published: Old Dominion University Libraries 2016
• Subjects: North Atlantic
• Online Access: https://dx.doi.org/10.25777/8cx1-0v89; https://digitalcommons.odu.edu/cee_etds/32/

The pace and effects of climate change are an area of constant focus for coastal engineers as evolving patterns in the atmosphere worldwide affect the oceans and coasts on a regional and global scale. Surface waves respond to changing wind patterns both locally and from propagating swell, and the difficulty in predicting future wind patterns is well-established. Expectations that climate change will result in more frequent and intense coastal storms and consequently greater wave heights in the North Atlantic are still unrealized, and recent forecasts from a variety of atmosphere-ocean coupled global climate models instead predict decreasing wave heights through the end of the century in many areas of the world, including the U.S. Atlantic coast. In this thesis, an analysis of trends in significant wave heights and extreme waves using hourly data recorded by the National Oceanic and Atmospheric Administration’s National Data Buoy Center buoys finds wave heights along the mid-Atlantic region of the U.S. east coast unchanged or beginning to trend downward from the later years of the 20th century into the 21st century. From the southernmost latitude in the study to the northernmost, a progressive change is evident with latitude. At the southernmost buoy, 44014, located off of Virginia Beach, VA, hourly significant wave heights are virtually unchanged during the time series (1.83e-6 m/year from 1991-2002 and -5.57e-6 m/year from 2003 - 2015). At buoy 44009, located off the southern tip of New Jersey, the trend reverses from slightly upward to slightly downward (+3.85e-5 m/year in 1986 - June 2001 versus - 2.42e-5 m/year from Jul 2001 - Dec 2015). Farthest north, at buoy 44025 south of Islip, NY, the trend reversal again occurs (+ 2.39e-5 m/year in April 1991 - Jan 2003 versus -2.41e-5 m/year in Jan 2003 - Dec 2015). Seasonal trends follow the same path with the most evident change being a 0.05 m/ year decrease in extreme waves in the northern region of the study area. Hindcast data from the U.S. Geological Survey allow for an extension of the climatology and analysis to 40 years and shows a clear decrease in storm wave heights.