Normally moving counter-clockwise, in the winter the Indian Ocean gyre
reverses direction due to the seasonal winds of the
South Asian Monsoon. In the summer, the land is warmer than the ocean, so surface winds blow from the ocean to the land. However, during the winter, these temperatures reverse, making the winds blow from the land to the ocean. Because most of the air pressure gradient is retained behind the
Tibetan plateau, air pressure gradients over the Indian Ocean and the gyre are small. This results in winds of moderate strength, due to the protection from the full force winds blowing off the Mongolian high pressure region. Because of these moderate, dry winds, the Winter Monsoon season in the Indian Ocean region is the dry season for most of
Southern Asia. Due to this seasonal wind cycle, the currents of the Indian Ocean, which make up the Indian Ocean gyre, are directly affected, causing reversal.[1]
There are trash vortices in each of the five major oceanic
gyres
The
Indian Ocean garbage patch, discovered in 2010, is a
marine garbage patch, a
gyre of
marine litter, suspended in the upper
water column of the central
Indian Ocean, specifically the Indian Ocean Gyre, one of the five major oceanic
gyres.[2][3][4][5][6][7] The patch does not appear as a continuous debris field. As with other patches in each of the five oceanic gyres, the plastics in it break down to ever smaller particles, and to constituent
polymers.[8] As with the other patches, the field constitutes an elevated level of
pelagic plastics,
chemical sludge, and other
debris; primarily particles that are invisible to the naked eye. The concentration of particle debris has been estimated to be approximately 10,000 particles per square kilometer.[9][10][11][12]
References
^Tomczak, Matthias & J. Stuart Godfrey: Regional Oceanography: and Introduction 2nd Edition. (2003).
ISBN8170353068
^For a discussion of the current sampling techniques and particle size, see Peter Ryan, Charles Moore et al., Monitoring the abundance of plastic debris in the marine environment. Phil. Trans. R. Soc. B 27 July 2009 vol. 364 no. 1526 1999–2012,
doi:
10.1098/rstb.2008.0207