Scientists are unable to explain why large portions of the Atlantic Ocean near the equator started cooling before returning to normal temperatures this summer.
The abnormal temperature patterns were observed in June in both the north and south sides of the equator when chunks of the mighty Atlantic cooled down before breaking the 40-year-old record of warm surface waters.
Postdoctoral researcher Franz Tuchen, who is behind the study, stated that seeing the oceans achieving cold and warm water is a normal phenomenon. Still, it is “really unprecedented” to see the rate at which the temperature change happened this year.
Another scientist, Michael McPhaden from the National Oceanic and Atmospheric Administration, who is overseeing a project that studies cold water spells in the Atlantic using buoy data, stated that the scientists are “scratching our heads” over the unexpected incident, adding that it could be a result of some feature that the scientific world does not “quite understand” yet.
Tuchen stated that the eastern equatorial Atlantic registered a sea surface temperature above 86 degrees Fahrenheit in February and March this year before starting to drop unexpectedly in June and reaching a historic low of 77 F in the chronically hot weather of July.
These temperature patterns brought the Atlantic near the historic phenomenon of “Atlantic Niña,” a climate phenomenon similar to La Niña but occurring in the Atlantic Ocean rather than the Pacific.
Just like La Niña, which is characterized by cooler-than-normal sea surface temperatures in the central and eastern Pacific, an Atlantic Niña involves cooler-than-normal sea surface temperatures in the tropical Atlantic region. As a result of this phenomenon, weather patterns in the regions surrounding the Atlantic, such as Africa, the Americas, and parts of Europe, can change and result in disturbed rainfall patterns.
Although the Pacific’s La Niña is a common occurrence, the Atlantic Niña last happened in 2013. The Atlantic Niña would have been official had cold temperatures persisted till August.
In normal circumstances, scientists attribute the cool sea surface temperature in this region to a process called equatorial upwelling. This is the process where stronger trade winds near the equator drive these cooling events by pushing warm water away, resulting in the rise of cold water from deeper layers.
However, scientists are particularly surprised because, in this specific case, the southeast side of the equator had weaker winds, which should have increased the water temperature.
Despite developing computer simulations of the event, scientists are still unable to reach any conclusion. Some of these simulations included studying the consequences of sudden changes in wind and water currents around the equator, but that did not turn out to be the cause of the anomaly.
