Veerabhadran Ramanathan and the Brown Clouds

Veerabhadran Ramanathan

Veerabhadran Ramanathan

On November 24, 1944Indian atmospheric scientist Veerabhadran Ramanathan was born. He has contributed to many areas of the atmospheric sciences including developments to general circulation models, atmospheric chemistry, and radiative transfer. But, he is best known for his 1999 discovery of the “Asian Brown Cloud” – wandering layers of air pollution as wide as a continent and deeper than the Grand Canyon.

Veerabhadran Ramanathan received his bachelor’s degree in engineering from Annamalai University, and a master’s degree from the Indian Institute of Science. In 1970, he arrived in the United States to study interferometry at the State University of New York at Stony Brook under the direction of Robert Cess. Before Ramanathan could begin working on his PhD research, Cess decided to change his research and focus on planetary atmospheres.

Ramanathan’s first major findings were in the mid-1970s and were related to the greenhouse effect of CFCs and other trace gases. Ramanathan further contributed to the early development of global circulation models and the detecting and attribution of climate change.

In later years, Veerabhadran Ramanathan was able to show that aerosols have a cooling effect on the surface of the planet, and at the top of the atmosphere, but the forcing at the top of the atmosphere was only one-third the magnitude as the surface forcing. During his work with the Central Equatorial Pacific Experiment, Ramanathan also noticed that absorbing black carbonaceous aerosols have a larger influence on climate than previously thought. This led to the development of the Indian Ocean Experiment (INDOEX).

As part of the Indian Ocean Experiment, which was led by Veerabhadran Ramanathan and Paul Crutzen during the early 1990s, they  discovered the widespread existence of atmospheric brown clouds covering much of the Indian Ocean region. They found that the vast majority of the aerosols were anthropogenic in origin, and that the surface cooling caused by the aerosols is more important than the atmospheric heating. These atmospheric brown clouds may have masked as much as 50% of the surface heating caused by the increase in carbon dioxide, and caused reduced precipitation during the Indian monsoon.

The cloud was also reported by NASA in 2004 and 2007. Although aerosol particles are generally associated with a global cooling effect, recent studies have shown that they can actually have a warming effect in certain regions such as the Himalayas. One major impact is on health. A 2002 study indicated nearly two million people die each year, in India alone, from conditions related to the brown cloud.

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