New evidence in the November issue of Nature reports ‘Arabian Sea tropical cyclones are intensified by emissions of black carbon and other aerosols’
Strong vertical wind shear can prevent the formation of tropical cyclones, even when ocean temperatures are otherwise warm enough to brew them up. Amato T. Evan et al. from the University of Virginia authored a paper published in the journal Nature (Nov 2nd), reporting increased emissions of black carbon, sulphates and other aerosols have increased sixfold since the 1930s, leading to a weakening of the southwesterly lower-level and easterly upper-level winds that define the monsoonal circulation over the Arabian Sea, leading to decreased vertical wind shear. As a result, these anthropogenic emissions seem to have caused an increase in the intensity of tropical cyclones in the pre-monsoon season.
The study uses a combination of observational, reanalysis and model data to demonstrate that the anomalous circulation, which is radiatively forced by these anthropogenic aerosols, reduces the basin-wide vertical wind shear, creating an environment more favourable for tropical cyclone intensification. Because most Arabian Sea tropical cyclones make landfall, these results suggest an additional impact on human health from regional air pollution.
Journal Reference: Amato T. Evan; James P. Kossin; Chul ‘Eddy’ Chung; V. Ramanathan. Nature 479 , 94–97 ( 02 November 2011 ) | doi:10.1038/nature10552.
Source: The above article (with editorial adaptions by Bare Essentials staff) was reprinted from materials provided by Nature online science journal.
