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Warming trends in Asia amplified by brown cloud solar absorption.
Nature 2007; 448(7153):575-8Nat

Abstract

Atmospheric brown clouds are mostly the result of biomass burning and fossil fuel consumption. They consist of a mixture of light-absorbing and light-scattering aerosols and therefore contribute to atmospheric solar heating and surface cooling. The sum of the two climate forcing terms-the net aerosol forcing effect-is thought to be negative and may have masked as much as half of the global warming attributed to the recent rapid rise in greenhouse gases. There is, however, at least a fourfold uncertainty in the aerosol forcing effect. Atmospheric solar heating is a significant source of the uncertainty, because current estimates are largely derived from model studies. Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly. We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 per cent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers.

Authors+Show Affiliations

Center for Clouds, Chemistry and Climate, Scripps Institution of Oceanography, UCSD, La Jolla, California 92037, USA. vramanathan@ucsd.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

17671499

Citation

Ramanathan, Veerabhadran, et al. "Warming Trends in Asia Amplified By Brown Cloud Solar Absorption." Nature, vol. 448, no. 7153, 2007, pp. 575-8.
Ramanathan V, Ramana MV, Roberts G, et al. Warming trends in Asia amplified by brown cloud solar absorption. Nature. 2007;448(7153):575-8.
Ramanathan, V., Ramana, M. V., Roberts, G., Kim, D., Corrigan, C., Chung, C., & Winker, D. (2007). Warming trends in Asia amplified by brown cloud solar absorption. Nature, 448(7153), pp. 575-8.
Ramanathan V, et al. Warming Trends in Asia Amplified By Brown Cloud Solar Absorption. Nature. 2007 Aug 2;448(7153):575-8. PubMed PMID: 17671499.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Warming trends in Asia amplified by brown cloud solar absorption. AU - Ramanathan,Veerabhadran, AU - Ramana,Muvva V, AU - Roberts,Gregory, AU - Kim,Dohyeong, AU - Corrigan,Craig, AU - Chung,Chul, AU - Winker,David, PY - 2007/02/02/received PY - 2007/06/13/accepted PY - 2007/8/3/pubmed PY - 2007/8/3/medline PY - 2007/8/3/entrez SP - 575 EP - 8 JF - Nature JO - Nature VL - 448 IS - 7153 N2 - Atmospheric brown clouds are mostly the result of biomass burning and fossil fuel consumption. They consist of a mixture of light-absorbing and light-scattering aerosols and therefore contribute to atmospheric solar heating and surface cooling. The sum of the two climate forcing terms-the net aerosol forcing effect-is thought to be negative and may have masked as much as half of the global warming attributed to the recent rapid rise in greenhouse gases. There is, however, at least a fourfold uncertainty in the aerosol forcing effect. Atmospheric solar heating is a significant source of the uncertainty, because current estimates are largely derived from model studies. Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly. We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 per cent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers. SN - 1476-4687 UR - https://www.unboundmedicine.com/medline/citation/17671499/Warming_trends_in_Asia_amplified_by_brown_cloud_solar_absorption_ L2 - https://doi.org/10.1038/nature06019 DB - PRIME DP - Unbound Medicine ER -