Big News Network.com (IANS) Wednesday 8th June, 2011
Widespread urban development alters weather patterns in a way that can help pollutants accumulate during summer on paved surfaces, rather than being blown out to sea, says a study.
The reason for this is that the proliferation of strip malls, subdivisions and other paved areas may interfere with the breeze needed to clear away smog and other pollution.
The international study, led by the National Centre for Atmospheric Research (NCAR) in the US, could have implications for the air quality of fast-growing coastal cities and other mid-latitude regions globally, the Journal of Geophysical Research-Atmospheres reports.
For instance, paved surfaces, an ugly facet of break-neck urbanisation worldwide, keep the city warmer than more natural surfaces, according to an NCAR statement.
Researchers found that because pavements soak up heat and keep land areas relatively warm overnight, the contrast between land and sea temperatures is reduced during the summer. This, in turn, causes a reduction in night time winds.
Consequently, overnight temperatures are often similar between the city and nearby offshore areas, which weakens summertime breezes and enables air pollution to build up.
The stagnant conditions also persist during the day because of larger-scale wind patterns. 'The developed area of Houston has a major impact on local air pollution,' said NCAR scientist Fei Chen, who led the study.
'If the city continues to expand, it's going to make the winds even weaker in the summertime, and that will make air pollution much worse,' he added.
The research team combined extensive atmospheric measurements with computer simulations to examine the impact of pavements on the breezes in the area.