The eastern Mediterranean Sea, a large basin surrounded by ancient cultural sites, is also a hotspot for climatology.
However, when it comes to understanding the extreme sea states that produce massive and potentially catastrophic waves, the region has received comparatively little attention.
Understanding rogue waves of the Eastern Mediterranean Sea
Iswanto Arif/Unsplash
Recognizing a knowledge gap, an international team of researchers led by Francesco Fedele, associate professor in Georgia Tech's School of Civil and Environmental Engineering, investigated potential hazards for ship navigation in the eastern Mediterranean, as per ScieceDaily.
They studied rogue waves, how they formed, and the likelihood of a ship encountering them while navigating the rough waters of intense storms.
Their findings shed light on the nature of extreme waves in the Mediterranean Sea and have the potential to advance technology for predicting rogue waves and maritime navigation in extreme weather conditions.
Rogue waves have long been observed in the western Mediterranean by eyewitnesses, including cruise ship passengers, and have been known to cause structural damage and fatalities.
Fedele collaborated with colleagues at the Technion-Israel Institute of Technology and the CAMERI Coastal and Marine Engineering Research Institute in Haifa, Israel, to investigate the case of the eastern Mediterranean.
The researchers used a novel theory of space-time wave extremes to simulate Israeli naval fleet ships navigating the waters of two major storms that hit the Mediterranean Sea in 2017 and 2018.
The researchers looked at the frequency of rogue wave occurrences as seen by an observer at a specific location on the sea's surface, such as an oil rig.
According to the team's statistical analysis, the largest observed waves during the two major storms have characteristics similar to the catastrophic El Faro, Andrea, and Draupner rogue waves, in which the asymmetry of the waves' crests and troughs was the dominant factor in creating rogue waves.
They discovered that rogue waves do not "steal" energy from neighboring waves or grow at their expense because the eastern Mediterranean basin is characterized by waves coming from all directions.
This phenomenon, known as modulational instability, has previously been used to better understand rogue waves.
However, Fedele claimed that it is only applicable when waves travel in the same direction, such as through a long channel, and thus does not apply in realistic seas.
The team's innovative space-time analysis of the most intense sea states also demonstrated the capacity to predict potential rogue hazards for ships of various sizes and cruise speeds navigating the rough waters of the analyzed storms.
According to Fedele, a surfer can serve as an analogy for the space-time effect of waves.
Surfers, as we all know, do not spend the entire day waiting for a large wave, he explained.
They swim around a certain area in order to increase their chances of encountering large waves, and they always do.
Similarly, a ship navigating waves will encounter more waves, and the likelihood of encountering a rogue wave is greater than that of an oil rig.
Scientists refer to rogue waves as "extreme storm waves" because they are larger than twice the size of surrounding waves, are highly unpredictable, and frequently come from directions other than the prevailing wind and waves, as per NOAA.
Most reports of extreme storm waves describe them as "walls of water," with steep sides and unusually deep troughs.
Due to the rarity of these waves, measurements and analysis of this phenomenon are extremely rare.
Rogue waves are still being studied to determine how and when they form, but there are several known causes:
Extreme waves form when swells travel across the ocean at different speeds and directions.
As these swells pass through each other, their crests, troughs, and lengths sometimes coincide and reinforce each other.
This process can result in unusually large, towering waves that vanish quickly. If the swells are traveling in the same direction, these mountainous waves can last for several minutes before subsiding.
When storm waves form in a water current opposite the normal wave direction, an interaction can occur, resulting in a shortening of the wave frequency.
This can cause the waves to join together dynamically, resulting in very large "rogue" waves. These are sometimes seen in the Gulf Stream and the Agulhas current.
Extreme waves created in this manner tend to last longer.
