The haze is caused by high concentrations of small particles known as aerosols that are usually less than a few micrometers in diameter. Comprised primarily of soot, sulfates, nitrates, organic particles, fly ash and mineral dust, the particles often reduced visibility over the open ocean to less than 10 kilometers, a range typically found near polluted regions of the United States and Europe. The haze layer also contains relatively high concentrations of gases, including carbon monoxide, various organic compounds, and sulfur dioxide, providing conclusive evidence that the haze layer is caused by pollution.
Asia and the Indian subcontinent, which together have a population of more than 2 billion people, emit large quantities of pollutants that can be carried to the Indian Ocean during the northern hemisphere winter by monsoon winds from the northeast. Preliminary results indicate that aerosols in the polluted region scatter the incoming solar radiation and reduce the amount of energy absorbed by the ocean surface by as much as 10 percent.
"If you cut the amount of sunlight going into the ocean, you will also
impact the amount of moisture evaporating from the sea surface either
regionally or globally and, consequently, the amount of rainfall that will be
generated," Ramanathan said. "So the entire hydrological cycle is being
perturbed." A reduction in the amount of sunlight reaching the ocean surface
can also have a detrimental effect on plant life that depends on photosynthesis,
including plankton, which
Contact: Cheryl Dybas
National Science Foundation