Atmospheric brown cloud
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The Indian Ocean brown cloud or Asian brown cloud is a layer of air pollution that recurrently covers parts of South Asia, namely the northern Indian Ocean, India, and Pakistan. Viewed from satellite photos, the cloud appears as a giant brown stain hanging in the air over much of South Asia and the Indian Ocean every year between January and March, possibly also during earlier and later months. The term was coined in reports from the UNEP
Indian Ocean Experiment The Indian Ocean Experiment (INDOEX) was a 1999 multinational scientific study designed to measure the transport of air pollution from Southeast Asia into the Indian Ocean. The project was led by Veerabhadran Ramanathan. Findings * Plumes of sulfat ...
(INDOEX). It was found to originate mostly due to Sikh farmers burning stubble in Punjab and to lesser extent Haryana. The debilitating air quality in Delhi is also due to the stubble burning in Punjab.Ramanathan, Veerabhadran ''et al.'' (2002
''The Asian brown cloud climate and other environmental impacts: impact study''
Center for Clouds, Chemistry and Climate, United Nations Environment Programme, Nairobi Kenya, , accessed 8 December 2008
The term ''atmospheric brown cloud'' is used for a more generic context not specific to the Asian region.


Causes

The Asian brown cloud is created by a range of airborne particles and pollutants from combustion (e.g., woodfires, cars, and factories),
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
burning and industrial processes with incomplete burning. The cloud is associated with the winter monsoon (November/December to April) during which there is no rain to wash pollutants from the air.Petit, C. W. (2003) "A darkening sky: A smoky shroud over Asia blocks both sun and rain" ''U.S. News & World Report'' (17 March 2003), 134(8): pp. 46-8


Observations

This pollution layer was observed during the Indian Ocean Experiment (INDOEX) intensive field observation in 1999 and described in the UNEP impact assessment study published 2002. Scientists in India claimed that the Asian Brown cloud is not something specific to Asia. Subsequently, when the United Nations Environment Programme (UNEP) organized a follow-up international project, the subject of study was renamed ''the Atmospheric Brown Cloud'' with focus on Asia. 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.


Impacts


Health problems

One major impact is on health. A 2002 study indicated nearly two million people die each year, in Asia alone, from conditions related to the brown cloud.


Regional weather

A second assessment study was published in 2008. It highlighted regional concerns regarding: * Changes of rainfall patterns with the Asian monsoon, as well as a delaying of the start of the Asian monsoon, by several weeks. The observed weakening Indian monsoon and in China northern drought and southern flooding is influenced by the clouds. * Increase in rainfall over the
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n Top End and
Kimberley Kimberly or Kimberley may refer to: Places and historical events Australia * Kimberley (Western Australia) ** Roman Catholic Diocese of Kimberley * Kimberley Warm Springs, Tasmania * Kimberley, Tasmania a small town * County of Kimberley, a ...
regions. A
CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government The Australian Government, also known as the Commonwealth Government, is the national government of Australia, a federal parliamentar ...
study has found that by displacing the thermal equator southwards via cooling of the air over East Asia, the monsoon which brings most of the rain to these regions has been intensified and displaced southward. * Retreat of the Hindu Kush- Himalayan glaciers and snow packs. The cause is attributed to rising air temperatures that are more pronounced in elevated regions, a combined warming effect of greenhouse gases and the Asian Brown Cloud. Also deposition of black carbon decreases the reflection and exacerbates the retreat. Asian glacial melting could lead to water shortages and floods for the hundreds of millions of people who live downstream. * Decrease of crop harvests. Elevated concentrations of surface ozone are likely to affect crop yields negatively. The impact is crop specific.


Cyclone intensity in Arabian Sea

A 2011 study found that pollution is making Arabian Sea cyclones more intense as the atmospheric brown clouds has been producing weakening wind patterns which prevent wind shear patterns that historically have prohibited cyclones in the Arabian Sea from becoming major storms. This phenomenon was found responsible for the formation of stronger storms in
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and
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that were the first recorded storms to enter the
Gulf of Oman The Gulf of Oman or Sea of Oman ( ar, خليج عمان ''khalīj ʿumān''; fa, دریای عمان ''daryâ-ye omân''), also known as Gulf of Makran or Sea of Makran ( ar, خلیج مکران ''khalīj makrān''; fa, دریای مکرا ...
.


Global warming and dimming

The 2008 report also addressed the global concern of
warming Warming may refer to: People *Eugenius Warming, (1841–1924), Danish botanist * Thomas Warming, (b. 1969), Danish illustrator, painter and author See also *Global warming *Warming up *Warming Land Warming Land is a peninsula in far northern G ...
and concluded that the brown clouds have masked 20 to 80 percent of
greenhouse gas A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
forcing in the past century. The report suggested that air pollution regulations can have large amplifying effects on global warming. Another major impact is on the polar ice caps. Black carbon ( soot) in the Asian Brown Cloud may be reflecting sunlight and dimming Earth below but it is warming other places by absorbing incoming radiation and warming the atmosphere and whatever it touches. Black carbon is three times more effective than carbon dioxide—the most common greenhouse gas—at melting polar ice and snow. Black carbon in snow causes about three times the temperature change as carbon dioxide in the atmosphere. On snow—even at concentrations below five parts per billion–dark carbon triggers melting, and may be responsible for as much as 94 percent of Arctic warming.


See also

* Asian Dust * Arctic haze * Air pollution in India *
Chemical Equator The chemical equator term and concept was coined in 2008 when researchers from University of York discovered a distinct divide between the polluted air and haze over Indonesia from the largely uncontaminated atmosphere over Australia. This divid ...
*
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2006 File:2006 Events Collage V1.png, From top left, clockwise: The 2006 Winter Olympics open in Turin; Twitter is founded and launched by Jack Dorsey; The Nintendo Wii is released; Montenegro 2006 Montenegrin independence referendum, votes to declare ...
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2009 File:2009 Events Collage V2.png, From top left, clockwise: The vertical stabilizer of Air France Flight 447 is pulled out from the Atlantic Ocean; Barack Obama becomes the first African American to become President of the United States; 2009 Iran ...
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2013 Southeast Asian haze The 2013 Southeast Asian haze was a haze crisis that affected several countries in Southeast Asia, including Brunei, Indonesia, Malaysia, Singapore and Southern Thailand, mainly during June and July 2013. The haze period was caused by large- ...


References


Further reading

* * Silva-Send, Nilmini (2007) ''Preventing regional air pollution in Asia : the potential role of the European Convention on Long Range Transboundary Air Pollution in Asian regions'' University of Kiel, Kiel, Germany,


External links


Bray, Marianne (2002) "'Asian Brown Cloud' poses global threat" CNN
from WebArchive {{DEFAULTSORT:Asian Brown Cloud Air pollution by region Climate of India Climate of Pakistan Indian Ocean Meteorology research and field projects Smog events South Asia Air pollution in India