Ocean winds and waves have slightly strengthened over last three decades

Over the last three decades, wind speeds and wave heights have increased, even if just a little, in most places around the world, with the greatest increases occurring in the Southern Ocean.

The new study reporting these results used global satellite data spanning more than thirty years, from 1985 to 2018. The analysis helps to refine the understanding of how these critical oceanic and atmospheric processes are influenced by the changing climate. Oceanic wind and wave patterns play an important role in a number of environmental and climate systems. Wind over open waters largely defines the roughness of the surface, which can greatly influence the transfer of both energy and carbon dioxide between the atmosphere and ocean. Also, wave heights can affect storm surge levels and coastal flooding during extreme weather events. The ability to determine small changes in global trends of winds and waves using long-term wind and wave records has remained challenging, however. Differences in the instrumentation of ocean buoys limit their ability to provide suitable data and concerns about the consistency of global satellite data have not yet been fully addressed.

Here, Ian Young and Agustinus Ribal took advantage of an extensive satellite database of wind speed and wave heights spanning more than thirty years (1985-2018). The dataset combines measurements from three independent instruments: altimeters (measuring wave height and wind speed), radiometers (measuring wind speed) and scatterometers (measuring wind speed and direction). Analyses of the resulting data show small, yet significant increases in global wind speed and wave heights, particularly during extreme conditions. Young and Ribal also find strong regional variations in these positive trends, with the Southern Ocean exhibiting the most significant increases, while trends in the equatorial Pacific and North Atlantic are much weaker.

According to the authors, the findings were confirmed across each satellite instrument, which suggests no negative impacts caused by inconsistent data or sampling patterns.

Credit: 
American Association for the Advancement of Science