Impact of California ’ s air pollution laws on black carbon and their implications for direct radiative forcing

Content Provider	Semantic Scholar
Author	Bahadur, Ranjit Feng, Yan Russell, Lynn M. Ramanathan, Veerabhadran
Copyright Year	2010
Abstract	We examine the temporal and the spatial trends in the concentrations of black carbon (BC) e recorded by the IMPROVE monitoring network for the past 20 years e in California. Annual average BC concentrations in California have decreased by about 50% from 0.46 mg m 3 in 1989 to 0.24 m gm 3 in 2008 compared to the corresponding reductions in diesel BC emissions (also about 50%) from a peak of 0.013 Tg Yr 1 in 1990 to 0.006 Tg Yr 1 by 2008. We attribute the observed negative trends to the reduction in vehicular emissions due to stringent statewide regulations. Our conclusion that the reduction in diesel emissions is a primary cause of the observed BC reduction is also substantiated by a significant decrease in the ratio of BC to non-BC aerosols. The absorption efficiency of aerosols at visible wavelengths e determined from the observed scattering coefficient and the observed BC e also decreased by about 50% leading to a model-inferred negative direct radiative forcing (a cooling effect) of 1.4 W m 2 ( 60%) over California. 2010 Elsevier Ltd. All rights reserved.
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://earthjustice.org/sites/default/files/black-carbon/impact-of-ca-air-pollution-laws.pdf
Alternate Webpage(s)	http://www-ramanathan.ucsd.edu/files/pr179.pdf
Alternate Webpage(s)	http://www-ramanathan.ucsd.edu/files/pr177.pdf
Language	English
Access Restriction	Open
Subject Keyword	Aerosol Dose Form Air Pollution Carbon Black Coefficient Command & Conquer:Yuri's Revenge Computer cooling Cool - action Diesel Emission - Male genitalia finding Gentamicins Inference Otoacoustic Emissions, Spontaneous Regulation wavelength
Content Type	Text
Resource Type	Article