Seasonal changes in carbonaceous aerosols over a tropical coastal location in response to meteorological processes

Aswini, A.R.; Hegde, Prashant; Nair, Prabha R.; Aryasree, S.

doi:10.1016/j.scitotenv.2018.11.366

Cited by 37 publications

(27 citation statements)

References 96 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The black carbon measurements were carried out using Aethalometers installed under the ARFI 150 (Aerosol Radiative Forcing over India) project. Since the measurements of aerosol composition are sparse over the Indian region, we have taken values reported from earlier studies for the winter season, and therefore the organic carbon and sulphate measurements are for different years than those of the model simulations (Ali et al, 2019;Aswini et al, 2019;George et al, 2008;Ram et al, 2010Ram et al, , 2012Rengarajan et al, 2011;Safai et al, 2008;Satsangi et al, 2012). Despite these shortcomings, compared to earlier studies, the present model configuration simulates black carbon mass loading and AOD 155 which are closer to the observed values (Nair et al, 2012).…”

Section: Methodssupporting

confidence: 52%

Amplification of South Asian haze by water vapour-aerosol interactions

Nair¹,

Giorgi²,

Hasyagar³

2020

Preprint

View full text Add to dashboard Cite

Abstract. Air pollution and wintertime fog over South Asia is a major concern due to its significant implications on air quality, visibility and health. Using a coupled regional climate model with on-line chemistry, we assess the contribution of the hygroscopic growth of aerosols (wet-dry) to the total aerosol optical depth and demonstrate that the increased surface cooling due to the hygroscopic effects of aerosols further increases the humidity in the boundary layer and thus enhances the confinement of pollutants through aerosol-boundary layer interactions. This positive feedback mechanism plays an important role in the prevalence of wintertime fog and low air quality conditions over South Asia, where water vapor contributes more than half of the aerosol optical depth. The aerosol-boundary layer interactions lead to the moistening of the boundary layer and drying of the free-troposphere, which amplifies the long-term trend in relative humidity over the Indo-Gangetic Plain during winter. Hence, the aerosol-water vapor interaction plays a decisive role in the formation and maintenance of the wintertime thick fog conditions over South Asia, which needs to be considered for planning mitigation strategies.

show abstract

Section: Methodssupporting

confidence: 52%

Amplification of South Asian haze by water vapour-aerosol interactions

Nair¹,

Giorgi²,

Hasyagar³

2020

Preprint

View full text Add to dashboard Cite

show abstract

“…For example, we investigate TOC as a whole even though primary and secondary species affect water uptake differently. There is no direct measurement of either in routine monitoring network operations, although fractionation can sometimes be used to infer information about sources and formation processes (Aswini et al, 2019;Cao et al, 2005;Chow et al, 2004). We group IMPROVE sites across the CONUS into 22 chemical climatology regions defined by the IMPROVE network ( Fig.…”

Section: Methodsmentioning

confidence: 99%

Differences in Fine Particle Chemical Composition on Clear and Cloudy Days

Christiansen¹,

Carlton²,

Henderson³

2020

Preprint

View full text Add to dashboard Cite

Abstract. Clouds are prevalent and alter fine particulate matter (PM2.5) mass and chemical composition. Cloud-affected satellite retrievals are subject to higher uncertainty and are often removed from data products, hindering quantitative estimates of tropospheric chemical composition during cloudy times. We examine surface PM2.5 chemical constituent concentrations in the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network in the United States during Cloudy and Clear Sky times defined using Moderate Resolution Imaging Spectroradiometer (MODIS) cloud flags from 2010-2014 with a focus on differences in particle hygroscopicity and aerosol liquid water (ALW). Cloudy and Clear Sky periods exhibit significant differences in PM2.5 mass and chemical composition that vary regionally and seasonally. In the eastern US, relative humidity alone cannot explain differences in ALW, suggesting emissions and in situ chemistry exert determining impacts. An implicit clear sky bias may hinder efforts to quantitatively understand and improve representation of aerosol-cloud interactions, which remain dominant uncertainties in models.

show abstract

“…As the charring of OC (the so-called pyrolytic carbon (PC)), occurring during the first step by incomplete combustion, may cause an incorrect quantification of the amount of OC and EC on each sample, the instrument is equipped with a laser and a detector continuously measuring the transmittance of the filter [49][50][51]: the splitting point between OC and EC is reached when the transmittance, after the decrease due to charring, regains the initial value, indeed allowing for a more accurate estimate of the measured quantities rather than relying on the only thermal behavior.…”

Section: The Thermal-optical Analysismentioning

confidence: 99%

Carbonaceous Aerosol in Polar Areas: First Results and Improvements of the Sampling Strategies

et al. 2021

View full text Add to dashboard Cite

While more and more studies are being conducted on carbonaceous fractions—organic carbon (OC) and elemental carbon (EC)—in urban areas, there are still too few studies about these species and their effects in polar areas due to their very low concentrations; further, studies in the literature report only data from intensive campaigns, limited in time. We present here for the first time EC–OC concentration long-time data records from the sea-level sampling site of Ny-Ålesund, in the High Arctic (5 years), and from Dome C, in the East Antarctic Plateau (1 year). Regarding the Arctic, the median (and the interquartile range (IQR)) mass concentrations for the years 2011–2015 are 352 (IQR 283–475) ng/m3 for OC and 4.8 (IQR: 4.6–17.4) ng/m3 for EC, which is responsible for only 3% of total carbon (TC). From both the concentration data sets and the variation of the average monthly concentrations, the influence of the Arctic haze on EC and OC concentrations is evident. Summer may be interesting owing to high concentration episodes mainly due to long-range transport (e.g., from wide wildfires in the Northern Hemisphere, as happened in 2015). The average ratio of EC/OC for the summer period is 0.05, ranging from 0.02 to 0.10, and indicates a clean environment with prevailing biogenic (or biomass burning) sources, as well as aged, highly oxidized aerosol from long-range transport. Contribution from ship emission is not evident, but this result may be due to the sampling time resolution. In Antarctica, a 1 year-around data set from December 2016 to February 2018 is shown, which does not present a clear seasonal trend. The OC median (and IQR) value is 78 (64–106) ng/m3; for EC, it is 0.9 (0.6–2.4) ng/m3, weighing for 3% on TC values. The EC/OC ratio mean value is 0.20, with a range of 0.06–0.35. Due to the low EC and OC concentrations in polar areas, correction for the blank is far more important than in campaigns carried out in other regions, largely affecting uncertainties in measured concentrations. Through the years, we have thus developed a new sampling strategy that is presented here for the first time: samplers were modified in order to collect a larger amount of particulates on a small surface, enhancing the capability of the analytical method since the thermo-optical analyzer is sensitive to carbonaceous aerosol areal density. Further, we have recently coupled such modified samplers with a sampling strategy that makes a more reliable blank correction of every single sample possible.

show abstract

Seasonal changes in carbonaceous aerosols over a tropical coastal location in response to meteorological processes

Cited by 37 publications

References 96 publications

Amplification of South Asian haze by water vapour-aerosol interactions

Amplification of South Asian haze by water vapour-aerosol interactions

Differences in Fine Particle Chemical Composition on Clear and Cloudy Days

Carbonaceous Aerosol in Polar Areas: First Results and Improvements of the Sampling Strategies

Contact Info

Product

Resources

About