| Autor: |
Venzac H; Laboratoire de Météorologie Physique, Observatoire de Physique du Globe de Clermont-Ferrand, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière, France., Sellegri K, Laj P, Villani P, Bonasoni P, Marinoni A, Cristofanelli P, Calzolari F, Fuzzi S, Decesari S, Facchini MC, Vuillermoz E, Verza GP |
| Jazyk: |
angličtina |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2008 Oct 14; Vol. 105 (41), pp. 15666-71. Date of Electronic Publication: 2008 Oct 13. |
| DOI: |
10.1073/pnas.0801355105 |
| Abstrakt: |
Rising air pollution levels in South Asia will have worldwide environmental consequences. Transport of pollutants from the densely populated regions of India, Pakistan, China, and Nepal to the Himalayas may lead to substantial radiative forcing in South Asia with potential effects on the monsoon circulation and, hence, on regional climate and hydrological cycles, as well as to dramatic impacts on glacier retreat. An improved description of particulate sources is needed to constrain the simulation of future regional climate changes. Here, the first evidence of very frequent new particle formation events occurring up to high altitudes is presented. A 16-month record of aerosol size distribution from the Nepal Climate Observatory at Pyramid (Nepal, 5,079 m above sea level), the highest atmospheric research station, is shown. Aerosol concentrations are driven by intense ultrafine particle events occurring on >35% of the days at the interface between clean tropospheric air and the more polluted air rising from the valleys. During a pilot study, we observed a significant increase of ion cluster concentrations with the onset of new particle formation events. The ion clusters rapidly grew to a 10-nm size within a few hours, confirming, thus, that in situ nucleation takes place up to high altitudes. The initiation of the new particle events coincides with the shift from free tropospheric downslope winds to thermal upslope winds from the valley in the morning hours. The new particle formation events represent a very significant additional source of particles possibly injected into the free troposphere by thermal winds. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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