Widespread reductions in haze across the United States from the early 1990s through 2011

Hand, Jenny L.; Schichtel, B. A.; Malm, William C.; Copeland, S.; Molenar, John V.; Frank, N. H.; Pitchford, Marc

doi:10.1016/j.atmosenv.2014.05.062

Cited by 84 publications

(102 citation statements)

References 24 publications

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“…Tracking multi-year trends in regional haze aerosols is a key function of the IMPROVE program (Malm et al 2002;White et al 2005;Murphy et al 2011;Hand et al 2012aHand et al ,b, 2013Hand et al , 2014. Consistent absorption data from the HIPS measurements have not previously been available for such analysis, so we will conclude this article by examining the implications for Fabs trends of the retrospective calibration introduced here.…”

Section: Absorption By Regional Haze Pm 25mentioning

confidence: 99%

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

White

Trzepla

Hyslop

et al. 2016

Aerosol Science and Technology

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Section: Absorption By Regional Haze Pm 25mentioning

confidence: 99%

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

White

Trzepla

Hyslop

et al. 2016

Aerosol Science and Technology

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“…During the last two decades, US NO x emissions have steadily declined due to effective regulations designed to decrease NO x contributions to ozone, fine particles, and acid deposition (16). Data from the National Emissions Inventory (NEI) Air Pollutant Emissions Trends (https://www.epa.gov/air-emissions-inventories/ air-pollutant-emissions-trends-data) indicate that NO x emissions decreased by nearly 41% from 1990 to 2010.…”

mentioning

confidence: 99%

Increasing importance of deposition of reduced nitrogen in the United States

Schichtel

Walker

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

354

253

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Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65% of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions.ammonia | dry deposition | wet deposition | nitrogen oxides | agriculture

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“…The dry PM 2.5 mass concentration was reconstructed mainly following the approach in fine PM reconstruction in IMPROVE (Hand et al, 2011 ), a revised formula developed by the IMPROVE program is used (Pitchford et al, 2007;Cao et al, 2012;Wang et al, 2013):…”

Section: Reconstruction Of Pm 25 and Light Extinctionmentioning

confidence: 99%

“…Both the original and the revised formulas have been applied in the studies in China (Yang et al, 2007;Tao et al, 2009;Zhang et al, 2012;Xiao et al, 2014). The major concern in applying the IMPROVE formulas is their universal applicability since the formulas were developed for rural/remote areas in United States (Sisler and Malm, 1994;Hand et al, 2011). This is mainly due to the fact that the dry mass scattering efficiencies (MSEs) and mass absorption efficiencies (MAEs) as well as the humidification factor f(RH) may be variable at different sites under different conditions (Watson, 2002;Jung et al, 2009;Tao et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

“…This method has been used in many intensive short-term studies (Tao et al, 2014b;Gao et al, 2015). When only aerosol composition data are available, the application of the IMPROVE formulas (including original and revised versions) is an easier and more widely used method than the Mie-theory method, which were established for the Interagency Monitoring of Protected Visual Environments (IMPROVE) Network in Unite States (Hand et al, 2011). The general expression is as follows:…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reconstructed Light Extinction Coefficients of Fine Particulate Matter in Rural Guangzhou, Southern China

Chen

Lai

Gao

et al. 2016

Aerosol Air Qual. Res.

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A one-year campaign was conducted to collected PM 2.5 samples in the rural area of Guangzhou, the largest megacity in South China, from March 2012 to February 2013. Mass concentration of PM 2.5 , carbonaceous fractions (i.e., organic carbon (OC) and elemental carbon (EC)) and 6 water-soluble ions were analyzed. Light extinction coefficient (b ext ) of fine particulate matter was reconstructed using the revised IMPROVE formula at the site. (NH 4 ) 2 SO 4 (AS) made a dominant contribution to the light extinction budget, accounting for 61.3% (155.6 ± 108.5 Mm -1 ) annually, with highest in autumn (68.0%) and lowest in winter (55.2%). Organic matter (OM) was the second largest contributor accounting for 20.5% (52.2 ± 42.7 Mm -1 ) with highest in winter (23.4%) and lowest in spring (18.0%). The relationship between reconstructed b ext and measured b ext was investigated under the influence of seasonality, visibility and PM 2.5 concentration. We found that b ext could be reconstructed using revised IMPROVE formula in high PM 2.5 days (threshold value of ~60 µg m -3 ). On other hand, the performance of formula was unsatisfactory for b ext reconstruction of in low PM 2.5 days, when meteorological conditions could have significant impact on visibility.

show abstract

Widespread reductions in haze across the United States from the early 1990s through 2011

Cited by 84 publications

References 24 publications

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

Increasing importance of deposition of reduced nitrogen in the United States

Reconstructed Light Extinction Coefficients of Fine Particulate Matter in Rural Guangzhou, Southern China

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