Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers

Abstract. In this paper we introduce new in situ observations of atmospheric aerosols, especially chemical composition, physical and optical properties, on the eastern brink of the heavily polluted Highveld area in South Africa. During the observation period between 11 February 2009 and 31 January 2011, the mean particle number concentration (size range 10-840 nm) was 6310 cm −3 and the estimated volume of sub-10 µm particles 9.3 µm 3 m −3 . The aerosol absorption and scattering coefficients at 637 nm were 8.3 Mm −1 and 49.5 Mm −1 , respectively. The mean single-scattering albedo at 637 nm was 0.84 and theÅngström exponent of scattering was 1.5 over the wavelength range 450-635 nm. The mean O 3 , SO 2 , NO x and H 2 S-concentrations were 37.1, 11.5, 15.1 and 3.2 ppb, respectively. The observed range of concentrations was large and attributed to the seasonal variation of sources and regional meteorological effects, especially the anticyclonic re-circulation and strong winter-time inversions. In a global context, the levels of gases and particulates were typical for continental sites with strong anthropogenic influence, but clearly lower than the most polluted areas of southeastern Asia. Of all pollutants observed at the site, ozone is the most likely to have adverse environmental effects, as the concentrations were high also during the growing season. The measurements presented here will help to close existing gaps in the ground-based global atmosphere observation system, since very little long-term data of this nature is available for southern Africa.

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“…Carmichael, 2003;Beirle et al, 2006), but below the concentrations of highly polluted parts of Asia.…”

Section: Trace Gasesmentioning

confidence: 91%

South African EUCAARI measurements: seasonal variation of trace gases and aerosol optical properties

et al. 2012

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“…In the Indian pre-monsoon (April-June), westerly winds blow dust across the Indo-Gangetic plain, where it is trapped by the Himalayas; the winter monsoon is associated with fog and thick haze from urban pollution and biomass burning aerosols (Prospero et al, 2002;Gautam et al, 2007Gautam et al, , 2011. Over the Indo-China peninsula, intense biomass burning during the pre-monsoon (February-April), in combination with urban emissions, leads to an optically-thick absorbing haze layer (Carmichael et al, 2003;See et al, 2006); monsoon rains during the summer washout much of the aerosol and cloud cover limits SeaWiFS's coverage. Similarly, near-persistent cloud cover means SeaWiFS coverage over Indonesia is sparse.…”

Section: South-eastern Asiamentioning

confidence: 99%

Global and regional evaluation of over-land spectral aerosol optical depth retrievals from SeaWiFS

et al. 2012

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Abstract. This study evaluates a new spectral aerosol optical depth (AOD) dataset derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over land. First, the data are validated against Aerosol Robotic Network (AERONET) direct-sun AOD measurements and found to compare well on a global basis. If only data with the highest quality flag are used, the correlation is 0.86 and 72 % of matchups fall within an expected absolute uncertainty of 0.05 + 20 % (for the wavelength of 550 nm). The quality is similar at other wavelengths and stable over the 13-yr (1997-2010) mission length. Performance tends to be better over vegetated, low-lying terrain with typical AOD of 0.3 or less, such as found over much of North America and Eurasia. Performance tends to be poorer for low-AOD conditions near backscattering geometries, where SeaWiFS overestimates AOD, or optically-thick cases of absorbing aerosol, where SeaWiFS tends to underestimate AOD. Second, the SeaWiFS data are compared with midvisible AOD derived from the Moderate Resolution Imaging Spectrometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR). All instruments show similar spatial and seasonal distributions of AOD, although there are regional and seasonal offsets between them. At locations where AERONET data are available, these offsets are largely consistent with the known validation characteristics of each dataset. With the results of this study in mind, the SeaWiFS over-land AOD record is suitable for quantitative scientific use.

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“…In Figure 1a we also give averaged measurements for the year 2000, taken from the WMO-GAW World Data Centre for surface ozone, EMEP/AIRBASE in Europe; and CASTNet in the United States. Measurements for India, China, and Africa are from various scientific studies (13)(14)(15)(16). Our analysis reveals that our mean model results agree within 5 ppbv with measurements in the USA, China, and Central Europe, and may overestimate the measured annual average with 10-15 ppbv in Africa, India and the Mediterranean.…”

Section: Surface Ozone Increasesmentioning

confidence: 99%

The Global Atmospheric Environment for the Next Generation

Dentener

Stevenson

Ellingsen

et al. 2006

Environ. Sci. Technol.

343

240

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Air quality, ecosystem exposure to nitrogen deposition, and climate change are intimately coupled problems: we assess changes in the global atmospheric environment between 2000 and 2030 using twenty-five state-of-the-art global atmospheric chemistry models and three different emissions scenarios. The first (CLE) scenario reflects implementation of current air quality legislation around the world, whilst the second (MFR) represents a more optimistic case in which all currently feasible technologies are applied to achieve maximum emission reductions. We contrast these scenarios with the more pessimistic IPCC SRES A2 scenario. Ensemble simulations for the year 2000 are consistent among models, and show a reasonable agreement with surface ozone, wet deposition and NO 2 satellite observations. Large parts of the world are currently exposed to high ozone concentrations, and high depositions of nitrogen to ecosystems. By 2030, global surface ozone is calculated to increase globally by 1.5±1.2 ppbv (CLE), and 4.3±2.2 ppbv (A2). Only the progressive MFR scenario will reduce ozone by -2.3±1.1 ppbv. The CLE and A2 scenarios project further increases in nitrogen critical loads, with particularly large impacts in Asia where nitrogen emissions and deposition are forecast to increase by a factor of 1.4 (CLE) to 2 (A2). Climate change may modify surface ozone by -0.8±0.6 ppbv, with larger decreases over sea than over land. This study shows the importance of enforcing current worldwide air quality legislation, and the major benefits of going further. Non-attainment of these air quality policy objectives, such as expressed by the SRES-A2 scenario, would further degrade the global atmospheric environment.

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Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers

Cited by 164 publications

References 13 publications

South African EUCAARI measurements: seasonal variation of trace gases and aerosol optical properties

South African EUCAARI measurements: seasonal variation of trace gases and aerosol optical properties

Global and regional evaluation of over-land spectral aerosol optical depth retrievals from SeaWiFS

The Global Atmospheric Environment for the Next Generation

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