Saturday , July 24 2021

Ocean waves and winds are getting stronger



During extreme storms, the ocean waves can be high over 20 meters or high as a five storey building.

More than just a product of our meteorological systems, waves are critical to sea shipping, beach stability, coastal floods or floods, and the design of coastal and offshore structures.

Extreme wave conditions are increasing worldwide. Photo: Getty Images

But our new study, published in Science, shows that these waves and the winds that generate them are increasing in size and doing so over the last 30 years.

These new measurements show that global average wave conditions are increasing, but more importantly, extreme wave conditions are rising even faster, with the largest increases occurring in the South Ocean.

We have found that the extreme winds in the South Ocean have increased by about 1.5 meters per second or by 8% over the last 30 years. Similarly, extreme waves in the same region increased by 30 centimeters or 5 per cent. Generally, winds grow faster than waves.

In addition to the increases in the South Ocean, extreme winds have also increased in the equatorial parts of the Pacific Ocean and the Atlantic Ocean, and the North Atlantic Ocean is approximately 0.6 meters per second over a period of 30 years.

These changes in the ocean wind and wave climate were determined by creating and analyzing a database of satellite wind speed and wave velocity measurements.

We used data from a total of 31 satellites in orbit between 1985 and 2018. For more than thirty years, these satellites made approximately 4 billion measurements of wind speed and wave height.

Global Trends in Final (90th Percent) Wind Speed ​​(Top) and Wave Height (Bottom) for 1985-2018 Areas where red shows rising values ​​while blue shows a decrease. Photo: Delivered

Although the dataset is huge, all satellites need to be very precisely calibrated. This was done by comparing satellite measurements with more than 80 ocean buoys all over the world. This is the largest and most detailed database of its type ever made.

It is important that within the combined data base there are three different forms of satellites – altimeters, radiometers and scalers. They use different methods to measure ocean waves, so combining them provides an even more stable set of data.

Expansion to extreme wave height is less uniform than winds. In addition to the increases in the South Ocean, the extremes of the extreme waves are also increasing in the North Atlantic. The speed of wind speed and wave height increase is shown in the above graphs.


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