Pirates Made Ocean Vortex "The Great Tourbillon" is inaccessible. So scientists have studied it from the space.

A huge oceanic whirlwind of Colorado's size appears every spring off the coast of Somalia and it's so big that scientists can see it from the air.

Satellite data recently revealed that it was even larger and lasted longer than expected.

Nicknamed the Grand Tourbillon, this clockwise rotating vortex was first described in 1866 by the British geographer Alexander Findley in a book on sailing in the Indian Ocean. Findley said his whirlwind was creating "a very heavy confusing sea" and urged sailors to avoid its mighty currents as African coasts approached. [Earth from Above: 101 Stunning Images from Orbit]

What is the cause of the great whirlwind? While the monsoon winds are expected to play a role, the vortex begins to form in April, about two months before the onset of the monsoon, and it persists more than a month after the end of the monsoon in September or October, according to a study published in the journal Geophysical Research Letters in 2013.

The whirlwind begins to turn with the arrival of annual waves of Rossby in the Indian Ocean. These slow waves, which measure only a few centimeters in height, carry reservoirs of stored energy that feed the vortex. Once the tourbillon is over, the monsoon winds arrive and continue to turn. at its peak, the Great Whirl can extend over 300 km (500 km) wide, according to the 2013 study.

Nevertheless, more in-depth research has proved difficult. Because the vortex is so big, it behaves differently than small vortices. According to a new study, pirates operating near the Somali coast have also hampered efforts to study it.

Observations from above

Scientists suspected that satellite data could provide information on the Grand Tourbillon. They analyzed satellite observations covering 23 years and examined 22 years of ocean circulation models. From this data, they developed a computer program to identify the fingerprints of the vortex and track it over time. They also analyzed the sea level data, while the center of the eddy rises to form a mound higher than the ocean around it.

In the new study, scientists have determined that the hot tub typically lasts about 198 days, which is much longer than the previous estimates, ie 140 days and 166 days. It also ended several months later than expected, prevailing until December and even in January in some cases.

And when the Grand Tourbillon was at its most intense, it covered an average of 106,000 square miles (275,000 square kilometers), reported the study's authors.

Since the Great Whirlpool is linked to the beginning of the monsoon, the new algorithm could also be used to detect patterns that shape the formation of the monsoon. This could help predict the amount of rain that the seasonal event induces in India, which affects agriculture across the country, said lead author Bryce Melzer of the study , satellite oceanographer at the Stennis Space Center in Mississippi.

"If we are about to tie these two projects together, we could have an advantage in predicting the strength of the monsoon, which has huge socio-economic impacts," Melzer said.

Their findings were published online April 30 in the journal Geophysical Research Letters.

Originally published on Science live.