Somali Current TYLER JANOSKI. First, let’s talk about the South-Asian Monsoon Monsoon develops because of temperature differences between land and sea.

Somali CurrentTYLER JANOSKI

First, let’s talk about the South-Asian Monsoon

Monsoon develops because of temperature differences between land and sea

Remember: Land heats and cools much quicker than water

The center of Asia is extremely continental

Summer: Thermal low over Tibet Air is forced upwards through heating

Subtropical high over the Indian Ocean

Winds flow northeastward

Winter: High pressure now over continental Asia Air now rises over the Indian Ocean

Winds flow southwestward

Somali Current Formation June to Sept: air flows towards low pressure in Asia

Jet of air called Findlater jet (or Somali Jet) forms from Western Intensification (it happens in the atmosphere too!) off coast of Somalia and Oman

Winds drive current from Southwest to Northeast

After Sept: winds die down

Dec-March: High pressure of Asia, air flows towards ocean

Current reverses direction and flows from Northeast to Southwest

Ekman Transport! As we all know, the net transport of water is directed to the

right of the wind stress

The flow in the Ekman layer during the summer is offshore

Cold water from the bottom Ekman layer flows up to replace it in upwelling

The strength of the winds and the Findlater jet create massive upwelling along the Somali coast

In the winter, the flow is directed on-shore, though it is weaker because of weaker winds

Cold air in the winter cools sea surface temperatures and promotes mixing

Comparison to other Western Boundary Currents

Somali current is the only Western boundary current that reverses direction

Relatively short because the Asian continent takes up most of Northern hemisphere above Indian ocean

Still experiences Western intensification (but only when it’s flowing Northeast in the summer)

Recorded speeds > 300cm/s

Upwelling during summer can lower temperatures by five degrees C

Upwelling=productive marine ecosystem

The Great Whirl With the Somali Current forms an extremely large

anticyclonic eddy called the Great Whirl

300km wide, extending almost 1000 m deep

Speed approx. 200cm/s

Researchers have discovered that it actuallystarts to form before the summer monsoon begins

Recently proposed theory: Rossby waves from previous monsoon propagate westward and concentrate energy off the coast

May play a role as predictor of monsoon strength

May influence the characteristics of the monsoon