One of the strangest ocean currents – swirling clockwise great vortex that occurs each summer off the coast of Somalia and the sea surface temperature changes, affecting the monsoon, carrying life-giving water to Asia.
A hundred years the sailors know that the Great vortex occurs simultaneously with the monsoon season in early June and disappears in September – about a month after the winds subside. Recall monsoons are among the most powerful air currents in the world (48 km / h).
A new study suggests that the Great whirlwind still closely associated with the monsoon than thought, but across the ocean, not the atmosphere: clockwise motion occurs nearly two months before the season winds. "Rossby waves give him energy long before it will start to do the winds," – says oceanographer Lisa Beal of the University of Miami (USA).
|The edge of the Great vortex seen here due to the high concentration of chlorophyll in the water. (Image IOCCG.)|
Great vortex is a monstrous anticyclone diameter of 300 km and a depth of about one kilometer. Surface current speed is 7 km / h
These Rossby waves – it is a slow ripple height of 5 cm, running from east to west. In the Indian Ocean, they are an echo of last year's monsoon, that is, how would link one season to another.
The authors have combined 18 years of satellite observations with data from the research expedition in 1995. Since then, the Arabian Sea, the scientists do not like to walk because of Somali pirates.
Whirlwind has approximately 166 days a year. Predict the location and orientation so far. Wandering around the Great vortex is determined by its own mini-cyclones. Spinning, it creates two or three cyclones along the flank of the edge, which move counter-clockwise. The interaction between the kids and the mother leads to the fact that for moving back and forth.
Great is not the only strange vortex, which can be found in the Arabian Sea. But this is the only place in the world where the flow every year, summer and winter, change their direction.
Understand how the flow in this part of the world react to the monsoons, it is extremely important, because this circulation is directly related to the temperature of the ocean surface, which affects the pattern of precipitation (remember El Nino Pacific). Because the heart of the Great vortex water is warmer than the edge, in a small cyclone for have complex effects on the climate and the amount of moisture in the monsoon.
The study is published in the Journal of Geophysical Research.
Prepared according to LiveScience.