Satellites map out Earth’s Great Whirl

Using more than two decades of satellite data scientists have mapped out the yearly evolution of the
Great Whirl, a gigantic weather formation that routinely forms off the coast of Somalia each year, lasts for more than half the year, and is closely linked to India’s annual monsoon season.

Using 23 years of satellite data, the new findings show the Great Whirl is larger and longer-lived than scientists previously thought. At its peak, the giant whirlpool is, on average, 275,000 square kilometers (106,000 square miles) in area and persists for about 200 days out of the year.

More than being just a curiosity, the Great Whirl is closely connected to the monsoon that drives the rainy season in India. Monsoon rains fuel India’s $2 trillion agricultural economy, but how much rain falls each year is notoriously difficult to forecast. If researchers can use their new method to discern a pattern in the Great Whirl’s formation, they might be able to better predict when India will have a very dry or very wet season compared to the average.

Below the fold is a short video showing the Whirl’s behavior during 2000. It appears that the Great Whirl is an atmospheric eddy formed by the prevailing east winds as they hit the coast of Somalia.
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