Increasing wave heights in the Gulf of Mexico driven by swell waves

Jesbin George^1*Matthew Hiatt¹Clinton S Willson²

• ¹Department of Oceanography and Coastal Science & Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States
• ²College of the Coast and Environment & Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States

This study analyzes the climatology, spatial and temporal trends of wind speeds and significant wave height (Hs) of combined wind-seas and swells and Hs of separated swells and wind-seas on annual and seasonal scales in the Gulf of Mexico (GoM) using 50 years of atmospheric reanalysis data. The Hs data showed strong agreement with in-situ measurements, with minimal bias (+/- < 0.08 m) and high correlation (r > 0.9) across both deep and shallow regions, although a slight underestimation is noted for wind speed data. Wind speeds showed seasonal variability in the GoM, though they did not exhibit significant long-term increases, except for a notable decrease (~ -1.0 cm/s/yr) along the southern Florida region. Conversely, the significant wave height of combined wind-seas and swells (Hs,c) exhibits a significant increase, particularly in the western and central GoM (> 0.2 cm/yr). Seasonally, Hs,c peaks in winter and is lowest in summer, with notable increases across most parts of the GoM. The increase in Hs of swell waves closely mirrors that of Hs,c.. In contrast, Hs of wind-seas is primarily driven by local winds, does not significantly increase over time, instead showing a strong seasonal coupling with wind speed and its trends across all seasons, suggesting that swell waves are likely responsible for the increase in Hs,c. The study highlights that the significant increase in Hs,c and Hs of swell waves along the GoM are primarily driven by remote swell waves from the Caribbean Sea and westward-propagating waves generated within the GoM, underscoring the growing importance of swell waves in shaping the wave climate and coastal dynamics.