scholarly journals Extreme smog challenge of India intensified by increasing lower tropospheric stability

2021 ◽  
Author(s):  
Ritesh Gautam ◽  
Piyushkumar Patel ◽  
Manoj Singh ◽  
Tianjia Liu ◽  
Loretta Mickley ◽  
...  
Keyword(s):  
Air Quality ◽  
Lower Troposphere ◽  
Mitigation Strategies ◽  
Radiative Effects ◽  
Surface Cooling ◽  
Northern India ◽  
Lower Tropospheric Stability ◽  
Autumn And Winter ◽  
Aerosol Radiative Effects

Extreme smog in India widely impacts air quality in late autumn and winter months. While the links between emissions and air quality are well-recognized, the association of smog and its intensification with climatic trends in the lower troposphere, where aerosol pollution and its radiative effects manifest, are not understood well. Here we use long-term satellite data to show a significant increase in aerosol exceedances over northern India, resulting in sustained atmospheric warming and surface cooling over the last two decades. We find several lines of evidence suggesting these aerosol radiative effects have induced a multidecadal (1980-2019) strengthening of lower tropospheric stability and an increase in relative humidity, leading to over fivefold increase in poor visibility days. Given this crucial aerosol-radiation-meteorological feedback driving the smog intensification, we anticipate results from this study will help inform mitigation strategies supporting stronger region-wide measures, which are critical for solving the smog challenge in India.

scholarly journals Aerosol radiative effects in the ultraviolet, visible, and near-infrared spectral ranges using long-term aerosol data series over the Iberian Peninsula

2014 ◽  
Vol 14 (7) ◽  
pp. 8779-8818 ◽  
Author(s):  
D. Mateos ◽  
M. Antón ◽  
C. Toledano ◽  
V. E. Cachorro ◽  
L. Alados-Arboledas ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Near Infrared ◽  
Radiative Properties ◽  
Radiative Effects ◽  
Spectral Ranges ◽  
Aerosol Radiative Effects ◽  
Aerosol Radiative

Abstract. A better understanding of the aerosol radiative properties is a crucial challenge for climate change studies. This study aims to provide a complete characterization of aerosol radiative effects in different spectral ranges within the shortwave (SW) solar spectrum. For this purpose, long-term datasets of aerosol properties from six AERONET stations located in the Iberian Peninsula (Southwestern Europe) are analyzed in term of climatology characterization and trends. Aerosol information is used as input to the libRadtran model in order to determine the aerosol radiative effect at the surface in the ultraviolet (AREUV), visible (AREVIS), near-infrared (ARENIR), and the entire SW range (ARESW) under cloud-free conditions. Over the whole Iberian Peninsula, aerosol radiative effects in the different spectral ranges are: −1.1 < AREUV < −0.7 W m−2, −5.7 < AREVIS < −3.8 W m−2, −2.8 < ARENIR < −1.7 W m−2, and −9.5 < ARESW < −6.1 W m−2. The four variables showed positive statistically significant trends between 2004 and 2012, e.g., ARESW increased +3.6 W m−2 per decade. This fact is linked to the decrease in the aerosol load, which presents a trend of −0.04 per unit of aerosol optical depth at 500 nm per decade, hence a reduction of aerosol effect on solar radiation at the surface is seen. Monthly means of ARE show a seasonal pattern with larger values in spring and summer. The aerosol forcing efficiency (AFE), ARE per unit of aerosol optical depth, is also evaluated in the four spectral ranges. AFE exhibits a dependence on single scattering albedo and a weaker one on Ångström exponent. AFE is larger (in absolute value) for small and absorbing particles. The contributions of the UV, VIS, and NIR ranges to the SW efficiency vary with the aerosol types. Aerosol size determines the fractions of AFEVIS/AFESW and AFENIR/AFESW. VIS range is the dominant region for all types, although non-absorbing large particles cause a more equal contribution of VIS and NIR intervals. The AFEUV / AFESW ratio shows a higher contribution for absorbing fine particles.

scholarly journals Amplification of South Asian haze by water vapour-aerosol interactions

2020 ◽  
Author(s):  
Vijayakumar Sivadasan Nair ◽  
Filippo Giorgi ◽  
Usha Keshav Hasyagar
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Air Quality ◽  
South Asia ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Climate Model ◽  
Mitigation Strategies ◽  
Surface Cooling ◽  
Gangetic Plain

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.

scholarly journals Amplification of South Asian haze by water vapour–aerosol interactions

2020 ◽  
Vol 20 (22) ◽  
pp. 14457-14471
Author(s):  
Vijayakumar Sivadasan Nair ◽  
Filippo Giorgi ◽  
Usha Keshav Hasyagar
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
South Asia ◽  
Water Vapour ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Climate Model ◽  
Mitigation Strategies ◽  
Surface Cooling ◽  
Gangetic Plain

Abstract. Air pollution and wintertime fog over South Asia is a major concern due to its significant implications for air quality, visibility and health. Using a regional climate model coupled with chemistry, we assess the contribution of the hygroscopic growth of aerosols (ambient–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 poor air quality conditions over South Asia, where water vapour contributes more than half of the aerosol optical depth. The aerosol–boundary layer interactions lead to 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 vapour interaction plays a decisive role in the formation and maintenance of the wintertime fog conditions over South Asia, which needs to be considered for planning mitigation strategies.

scholarly journals Aerosol radiative effects in the ultraviolet, visible, and near-infrared spectral ranges using long-term aerosol data series over the Iberian Peninsula

2014 ◽  
Vol 14 (24) ◽  
pp. 13497-13514 ◽  
Author(s):  
D. Mateos ◽  
M. Antón ◽  
C. Toledano ◽  
V. E. Cachorro ◽  
L. Alados-Arboledas ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Near Infrared ◽  
Fine Particles ◽  
Radiative Properties ◽  
Radiative Effects ◽  
Spectral Ranges ◽  
Aerosol Radiative Effects ◽  
Aerosol Types ◽  
Aerosol Radiative

Abstract. A better understanding of aerosol radiative properties is a crucial challenge for climate change studies. This study aims at providing a complete characterization of aerosol radiative effects in different spectral ranges within the shortwave (SW) solar spectrum. For this purpose, long-term data sets of aerosol properties from six AERONET stations located in the Iberian Peninsula (southwestern Europe) have been analyzed in terms of climatological characterization and inter-annual changes. Aerosol information was used as input for the libRadtran model in order to determine the aerosol radiative effect (ARE) at the surface in the ultraviolet (AREUV), visible (AREVIS), near-infrared (ARENIR), and the entire SW range (ARESW) under cloud-free conditions. Over the whole Iberian Peninsula, yearly aerosol radiative effects in the different spectral ranges were found to be −1.1 < AREUV < −0.7, −5.7 < AREVIS < −3.5, −2.6 < ARENIR < −1.6, and −8.8 < ARESW < −5.7 (in W m−2). Monthly means of ARE showed a seasonal pattern with larger values in spring and summer. The aerosol forcing efficiency (AFE), ARE per unit of aerosol optical depth, has also been evaluated in the four spectral ranges. AFE exhibited a dependence on single scattering albedo as well as a weaker one on the Ångström exponent. AFE is larger (in absolute value) for small and absorbing particles. The contributions of the UV, VIS, and NIR ranges to the SW efficiency varied with the aerosol types. The predominant aerosol size determined the fractions AFEVIS/AFESW and AFENIR/AFESW. The AFEVIS was the dominant contributor for all aerosol types, although non-absorbing large particles caused more even contribution of VIS and NIR intervals. The AFEUV / AFESW ratio showed a higher value in the case of absorbing fine particles.

scholarly journals Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

2016 ◽  
Vol 16 (1) ◽  
pp. 247-264 ◽  
Author(s):  
Y. Feng ◽  
V. R. Kotamarthi ◽  
R. Coulter ◽  
C. Zhao ◽  
M. Cadeddu
Keyword(s):  
Boundary Layer ◽  
South Asia ◽  
Lower Troposphere ◽  
Longwave Radiation ◽  
Radiative Heating ◽  
Lower Atmosphere ◽  
Radiative Effects ◽  
Northern India ◽  
Absorbing Aerosols ◽  
Aerosol Radiative

Abstract. Aerosol radiative effects and thermodynamic responses over South Asia are examined with the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of aerosol optical depths (AODs) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in northern India. The WRF-Chem model is found to heavily underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model's low bias is due to aerosol extinctions below  ∼  2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profiles averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to −0.7 K day−1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond differently between Case I and Case II, underlining the importance of determining the exact portion of scattering or absorbing aerosols that lead to the underestimation of aerosol optical depth in the model. In addition, the model results suggest that both the direct radiative effect and rapid thermodynamic responses need to be quantified for understanding aerosol radiative impacts.

Budapest airport air quality long-term studies by remote sensing with DOAS and FTIR with focus upon runway emissions

2007 ◽  
Author(s):  
Klaus Schäfer ◽  
Gregor Schürmann ◽  
Carsten Jahn ◽  
Candy Matuse ◽  
Herbert Hoffmann ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Air Quality ◽  
Long Term Studies

scholarly journals Advances in Air Quality Monitoring and Assessment

2021 ◽  
Vol 11 (13) ◽  
pp. 5817
Author(s):  
Thomas Maggos
Keyword(s):  
Air Quality ◽  
Quality Monitoring ◽  
Air Quality Monitoring

Air quality monitoring is a long-term assessment of pollutant levels that helps to assess the extent of pollution and provide information about air quality trends [...]

scholarly journals The Diamond League athletic series: does the air quality sparkle?

2021 ◽  
Author(s):  
James R. Hodgson ◽  
Lee Chapman ◽  
Francis D. Pope
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Performance Metrics ◽  
Urban Air Pollution ◽  
Quality Data ◽  
Performance Variation ◽  
Short And Long Term ◽  
Respiratory Conditions ◽  
Race Performance

AbstractUrban air pollution can have negative short- and long-term impacts on health, including cardiovascular, neurological, immune system and developmental damage. The irritant qualities of pollutants such as ozone (O3), nitrogen dioxide (NO2) and particulate matter (PM) can cause respiratory and cardiovascular distress, which can be heightened during physical activity and particularly so for those with respiratory conditions such as asthma. Previously, research has only examined marathon run outcomes or running under laboratory settings. This study focuses on elite 5-km athletes performing in international events at nine locations. Local meteorological and air quality data are used in conjunction with race performance metrics from the Diamond League Athletics series to determine the extent to which elite competitors are influenced during maximal sustained efforts in real-world conditions. The findings from this study suggest that local meteorological variables (temperature, wind speed and relative humidity) and air quality (ozone and particulate matter) have an impact on athletic performance. Variation between finishing times at different race locations can also be explained by the local meteorology and air quality conditions seen during races.

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