digplanet beta 1: Athena
Share digplanet:


Applied sciences






















The Indian Monsoon Current refers to the seasonally varying ocean current regime found in the tropical regions of the northern Indian Ocean. During winter, the flow of the upper ocean is directed westward from near the Indonesian Archipelago to the Arabian Sea. During the summer, the direction reverses, with eastward flow extending from Somalia into the Bay of Bengal. These variations are due to changes in the wind stress associated with the Indian monsoon. The seasonally reversing open ocean currents that pass south of India are referred to as the Winter Monsoon Current and the Summer Monsoon Current (alternately, the Northeast Monsoon Current and the Southwest Monsoon Current).[1] The Somali Current, which is strongly linked to the Indian monsoon, is also discussed in this article.


Historical perspective[edit]

Although Mariners have been aware of the existence of the Monsoon current for nearly one thousand years, a detailed understanding did not emerge until after the International Indian Ocean Expedition of the 1960s.[1] The World Ocean Circulation Experiment of the mid 1990s permitted detailed measurement of these currents through an extensive field campaign.[2]

Atmospheric forcing[edit]

In the northern hemisphere tropical regions of the Atlantic and Pacific oceans, surface winds blow predominantly from the northeast year round, with westward-flowing ocean currents underneath. The Indian Ocean differs from the Atlantic and Pacific in that a continental landmass forms a complete northern boundary at relatively low latitudes. Monsoonal circulations are driven by the differences in temperature between land masses and adjacent oceans.[3] Because water has a larger thermal capacity than air, land surfaces will heat more rapidly during the summer season. The Indian monsoon consists of two phases. During the northern hemisphere winter, the cool Asian landmass contains a broad area of high pressure, whereas lower pressures prevail over the warmer Indian ocean and hot Australian continent. This pressure pattern helps to reinforce the northeasterly trade winds. During the northern hemisphere summer, the Asian landmass (especially the Indian subcontinent) heats considerably, generating an area of low pressure to the north. Circulation about this low generates strong winds from the southwest over the Arabian Sea and along the Somali coast. These winds are enhanced by the formation of an atmospheric western boundary current created by the high terrain over eastern Africa.

A consequence of the Coriolis effect, Ekman theory explains that oceanic flow at the surface is directed at 45 degrees to the right of the wind stress in the Northern Hemisphere. Thus, winds blowing from the southwest result in eastward currents, while winds blowing from the northeast result in westward currents.

Structure and evolution[edit]

Winter season structure[edit]

The Winter Monsoon Current extends from the Bay of Bengal, around India and Sri Lanka, and across the Arabian Sea at a latitude of approximately 8 degrees North. Currents flow to the southwest along the coast of Somalia to the equator.

Measurements of the strengths of these currents have been obtained from ship drift records. The Northeast Monsoon Current is westward only during the months of January through March, and is strongest in February when it reaches 50 cm s−1.[4] Estimates of westward volume transport range from 7 to 14 Sverdrups.[1]

Summer season structure[edit]

The Somali Current, which describes the flow along the Horn of Africa from the equator to around 9 degrees north,[5] also shifts direction seasonally with the monsoon winds. It eventually separates from the coastline, turning to the right as it enters the Arabian Sea. The Summer Monsoon Current, located between 10 and 15 North latitude in the Arabian Sea, bends around India and Sri Lanka, and enters the Bay of Bengal. The Great Whirl is a gyre located around 10 N and 55 E, and is only present during the summer season.

During the summer when the current flows toward the northeast, Ekman transport (to the right of the flow in the Northern Hemisphere) is offshore, transporting warmer waters deeper into the Arabian sea, and permitting upwelling of cooler waters along the coast. This sea surface temperature pattern (cooler waters west of warmer waters) reinforces the northward current through geostrophic flow. The Southwest Monsoon Current is eastward from April through November, and reaches a peak intensity of 30 cm s−1 during the summer months.[4] During a 1995 field campaign, the Somali current was measured to transport 37 +/- 5 Sv during mid-September.[6]


The rapid initiation of seasonal currents (over the time period of several weeks) can be explained theoretically in terms of linear theory with a Rossby wave response.[5] The Monsoon Current can also be viewed in terms of local forcing processes that act in concert to create the mature, basin-wide system.[1] The evolution of these currents have been reproduced in dynamical models of the ocean-atmosphere system.[2]

See also[edit]


  1. ^ a b c d Shankar, D., P. N. Vinayachandran and A. S. Unnikrishnan, 2002: The monsoon currents in the north Indian Ocean, Progress In Oceanography, Volume 52, Issue 1, Pages 63-120.
  2. ^ a b Schott, Friedrich A. and Julian P. McCreary, Jr., 2001: The monsoon circulation of the Indian Ocean, Progress In Oceanography, Volume 51, Issue 1, Pages 1-123.
  3. ^ Savtchenko, Andrey. "An assessment of the Indian Ocean, Monsoon, and Somali Current using NASA's AIRS, MODIS, and QuikSCAT data". NASA Goddard Earth Sciences Data and Information Services Center, Code 610.2, L-3 Communications Government Service Inc. Retrieved on 2008-11-03.
  4. ^ a b Hastenrath, Stefan and Lawrence Greischar, 1991: The Monsoonal Current Regimes of the Tropical Indian Ocean: Observed Surface Flow Fields and Their Geostrophic and Wind-Driven Components, Journal of Geophysical Research, Vol. 96, No. C7, Pages 12,619–12,633.
  5. ^ a b Lighthill, M.J., 1969: Dynamic Response of the Indian Ocean to Onset of the Southwest Monsoon, Philosophical Transactions of the Royal Society of London, Series A, Mathematical and Physical Sciences, Vol. 265, No. 1159, pp. 45-92.
  6. ^ Beal, Lisa and Theresa K. Chereskin, 2003: The volume transport of the Somali Current during the 1995 southwest monsoon, Deep Sea Research Part II: Topical Studies in Oceanography, Volume 50, Issues 12-13, Pages 2077-2089.

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Indian_Monsoon_Current — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
14610 videos foundNext > 

Cbse School Video Tutorial Geography 4 climate the mechanism of monsoons

Cbse School Video Tutorial Mathematics AA Similarity Criterion Cbse School Video Tutorial Magnetism and Matter Cbse School Video Tutorial Internal Structure and Working of Human Eyes Cbse ...

Indian Monsoons

Factual video about the monsoons experienced by India every year, made for an A2 project. Song: Was it a dream? Artist: 30 Seconds to Mars.

G7/P5: Indian Monsoon Mechanism & Seasons of India

Language: Hindi, Topics Covered: 1. Indian monsoon: unique features, mechanism 2. Tropical easterly Jet 3. Pressure system of earth 4. Second equatorial trough 5. Somali Jet and Somali current...

Monsoon Kerala India

Kerala receives most of its rainfall in two distinguished monsoon seasons. For more information on this video click - http://www.indiavideo.org/kerala/travel/monsoon-kerala-2700.php#Desc ...

Understanding the Indian monsoon and its variability - Sulochana Gadgil

Understanding the Indian monsoon and its variability Sulochana Gadgil, CAOS, IISc. DISCUSSION MEETING: MATHEMATICAL PERSPECTIVES ON CLOUDS, CLIMATE, AND TROPICAL ...

Monsoon: The Indian Ocean and the Future of American Power with Robert Kaplan

On October 25, 2010, Robert Kaplan visited the Belfer Center for Science and International Affairs to discuss his new book, "Monsoon: The Indian Ocean and the Future of American Power." Kaplan...

Pastor Paul Begley - Sepember 7, 2014 Indian Monsoon & Steven Hawking

Pastor Paul Begley - Sepember 7, 2014 Indian Monsoon & Steven Hawking Monsoon rains have killed 160 in India and 128 in Pakistan in the Kasmir region. Also a Temple has been submerged in...

Monsoon rain from Kerala, India !

This short video was taken when the rampaging monsoon was at its wild best in Kozhikode, north Kerala in the southwest of India. It was taken from the relative safety of my office through the...

Parts of western India could face drought due to poor monsoon, govt warns

Watch ABN Andhrajyothy, the no 1 Telugu news channel, a 24/7 LIVE news channel dedicated to live reports, exclusive interviews, breaking news, sport, weather, entertainment, business updates...

India should brace for 'sub-normal' monsoon

The country needs to brace for a 'sub-normal' monsoon. In its April 2014 forecast, the India Meteorological Department had predicted that the country as a whole is likely to get about 95 per...

14610 videos foundNext > 

1 news items

Chandigarh Tribune
Sat, 17 Jun 2006 10:37:30 -0700

Interestingly, the Indian monsoon current is formed due to a high-pressure area near a small island in the Southern Hemisphere over the South Indian Ocean called Mascarene. Mascarene, located at 30 degree south latitude and 70 degree east longitude, ...

Oops, we seem to be having trouble contacting Twitter

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!

Searchlight Group

Digplanet also receives support from Searchlight Group. Visit Searchlight