Black carbon sanitary burden in the Indo-Gangetic plain: exposures, risks and mitigation

2020 ◽  
Author(s):  
Shubha Verma ◽  
Sanhita Ghosh ◽  
Olivier Boucher ◽  
Rong Wang ◽  
Laurent Menut ◽  
...  
Keyword(s):  
Black Carbon ◽  
Urban Area ◽  
Transport Model ◽  
Thermal Power ◽  
Surface Concentration ◽  
Population Exposure ◽  
Chemical Transport Model ◽  
Modeling Framework ◽  
Gangetic Plain ◽  
Indo Gangetic Plain

Abstract A large discrepancy between simulated and observed black carbon (BC) surface concentrations over the densely populated Indo-Gangetic plain (IGP) has so far limited our ability to assess the magnitude of BC sanitary impacts in terms of population exposure, morbidity, and mortality. We evaluate these impacts using an integrated modeling framework, including a successfully predicted BC surface concentration in a high-resolution chemical transport model CHIMERE with observationally-constrained BC emissions, combined with consistent health functions for BC. Population exposure to BC is noteworthy, with more than 60 million people identified living over hotspots of BC concentration (wintertime mean > 20 μg m−3). A fraction of 62% of the total cardiovascular diseases mortality (CVM) burden for the megacity is found attributable to wintertime BC exposure. The semi-urban area has 50% of the CVM burden attributable to BC exposure in the total population over the IGP. More than 400 thousand lives can potentially be saved from CVM annually, by implementing prioritized emission reduction from the combustion of domestic biofuel in the semi-urban area, and diesel oil in transportation and coal in thermal power plant and brick kiln industries in megacities.

scholarly journals A global 3-D CTM evaluation of black carbon in the Tibetan Plateau

2014 ◽  
Vol 14 (13) ◽  
pp. 7091-7112 ◽  
Author(s):  
C. He ◽  
Q. B. Li ◽  
K. N. Liou ◽  
J. Zhang ◽  
L. Qi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Black Carbon ◽  
Transport Model ◽  
The Tibetan Plateau ◽  
Emission Inventories ◽  
Chemical Transport Model ◽  
Central Plateau ◽  
Gangetic Plain ◽  
Rural Sites ◽  
Indo Gangetic Plain

Abstract. We systematically evaluate the black carbon (BC) simulations for 2006 over the Tibetan Plateau by a global 3-D chemical transport model (CTM) (GEOS-Chem) driven by GEOS-5 assimilated meteorological fields, using in situ measurements of BC in surface air, BC in snow, and BC absorption aerosol optical depth (AAOD). Using improved anthropogenic BC emission inventories for Asia that account for rapid technology renewal and energy consumption growth (Zhang et al., 2009; Lu et al., 2011) and improved global biomass burning emission inventories that account for small fires (van der Werf et al., 2010; Randerson et al., 2012), we find that model results of both BC in surface air and in snow are statistically in good agreement with observations (biases < 15%) away from urban centers. Model results capture the seasonal variations of the surface BC concentrations at rural sites in the Indo-Gangetic Plain, but the observed elevated values in winter are absent. Modeled surface-BC concentrations are within a factor of 2 of the observations at remote sites. Part of the discrepancy is explained by the deficiencies of the meteorological fields over the complex Tibetan terrain. We find that BC concentrations in snow computed from modeled BC deposition and GEOS-5 precipitation are spatiotemporally consistent with observations (r = 0.85). The computed BC concentrations in snow are a factor of 2–4 higher than the observations at several Himalayan sites because of excessive BC deposition. The BC concentrations in snow are biased low by a factor of 2 in the central plateau, which we attribute to the absence of snow aging in the CTM and strong local emissions unaccounted for in the emission inventories. Modeled BC AAOD is more than a factor of 2 lower than observations at most sites, particularly to the northwest of the plateau and along the southern slopes of the Himalayas in winter and spring, which is attributable in large part to underestimated emissions and the assumption of external mixing of BC aerosols in the model. We find that assuming a 50% increase of BC absorption associated with internal mixing reduces the bias in modeled BC AAOD by 57% in the Indo-Gangetic Plain and the northeastern plateau and to the northeast of the plateau, and by 16% along the southern slopes of the Himalayas and to the northwest of the plateau. Both surface BC concentration and AAOD are strongly sensitive to anthropogenic emissions (from China and India), while BC concentration in snow is especially responsive to the treatment of BC aerosol aging. We find that a finer model resolution (0.5° × 0.667° nested over Asia) reduces the bias in modeled surface-BC concentration from 15 to 2%. The large range and non-homogeneity of discrepancies between model results and observations of BC across the Tibetan Plateau undoubtedly undermine current assessments of the climatic and hydrological impact of BC in the region and thus warrant imperative needs for more extensive measurements of BC, including its concentration in surface air and snow, AAOD, vertical profile and deposition.

scholarly journals Wintertime radiative effects of black carbon (BC) over Indo-Gangetic Plain as modelled with new BC emission inventoriesin CHIMERE

2020 ◽  
Author(s):  
Sanhita Ghosh ◽  
Shubha Verma ◽  
Jayanarayanan Kuttippurath ◽  
Laurent Menut
Keyword(s):  
Black Carbon ◽  
Climate Model ◽  
Transport Model ◽  
Indian Subcontinent ◽  
Chemical Transport Model ◽  
Surface Cooling ◽  
Gangetic Plain ◽  
Bottom Up ◽  
Radiative Perturbation ◽  
Indo Gangetic Plain

Abstract. To reduce the uncertainty in the black carbon (BC) induced climatic impacts from the global and regional aerosol-climate model simulations, it is a foremost requirement to improve the prediction of modelled BC distribution. And that specifically, over the regions where the atmosphere is loaded with a large amount of BC, e.g., the Indo-Gangetic plain (IGP) in the Indian subcontinent. Here we present the wintertime radiative perturbation due to BC with an efficiently modelled BC distribution over the IGP in a high-resolution (0.1° × 0.1°) chemical transport model, CHIMERE, implementing new BC emission inventories. The model efficiency in simulating the observed BC distribution was examined executing five simulations: Constrained and bottomup (Smog, Cmip, Edgar, Pku) implementing respectively, the recently estimated India-based constrained BC emission and the latest bottom-up BC emissions (India-based: Smog-India, and global: Coupled Model Intercomparison Project phase 6 (CMIP6), Emission Database for Global Atmospheric Research-V4 (EDGAR-V4) and Peking University BC Inventory (PKU)). A low estimated value of the normalised mean bias (NMB) and root mean square error (RMSE) from Constrained estimated BC concentration (NMB: < 17 %) and aerosol optical depth due to BC (BC-AOD) (NMB: 11 %) indicated that simulation with constrained BC emissions in CHIMERE could simulate the distribution of BC pollution over the IGP more efficiently than with the bottom-up. The large BC pollution covering the IGP region comprised of wintertime all-day (daytime) monthly mean BC concentration and BC-AOD from the Constrained, respectively, in the range 14–25 (6–8) µg m−3 and 0.04–0.08, with a strong correlation between the variance in BC emission and simulated BC mass concentration or BC-AOD. Five main hotspot locations were identified in and around Delhi (northern-IGP), Prayagraj (or Allahabad)-Varanasi (central-IGP), Patna-Palamu (upper/lower mideastern-IGP), and Kolkata (eastern-IGP). The wintertime radiative perturbation due to BC aerosols from the Constrained included a wide-spread enhancement in atmospheric radiative warming by 2–3 times and a reduction in surface cooling by 10 %–20 %, with net warming at the top of atmosphere (TOA) of 10–15 W m−2, compared to the atmosphere without BC, for which, a net cooling at the TOA was, although, exhibited. These perturbations were spotted being the strongest around megacities (Kolkata and Delhi), and were inferred as 30 %–50 % lower from the bottomup than the Constrained.

scholarly journals A global 3-D CTM evaluation of black carbon in the Tibetan Plateau

2014 ◽  
Vol 14 (6) ◽  
pp. 7305-7354
Author(s):  
C. He ◽  
Q. B. Li ◽  
K. N. Liou ◽  
J. Zhang ◽  
L. Qi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Black Carbon ◽  
Transport Model ◽  
The Tibetan Plateau ◽  
Chemical Transport Model ◽  
Gangetic Plain ◽  
Remote Sites ◽  
Rural Sites ◽  
Indo Gangetic Plain ◽  
Good Agreement

Abstract. We evaluate the black carbon (BC) simulations for 2006 over the Tibetan Plateau by a global 3-D chemical transport model using surface observations of BC in surface air and in snow and BC absorption aerosol optical depth (AAOD). Using updated Asian anthropogenic BC emissions (Lu et al., 2011; Zhang et al., 2009) and global biomass burning emissions (Randerson et al., 2012; van der Werf et al., 2010), model results of both surface BC and BC in snow are statistically in good agreement with observations (biases < 15%). Model results capture the seasonal variation of surface BC concentration, but the observed wintertime high values at rural sites in the Indo-Gangetic Plain are absent in the model. Model results are in general agreement with observations (within a factor of two) at remote sites. Model simulated BC concentrations in snow are spatiotemporally consistent with observations at most sites. We find that modeled BC AAOD are significantly lower than observations to the northwest of the Plateau and along the southern slopes of the Himalayas during winter and spring, reflecting model deficiencies in emissions, topography and BC mixing state. We find that anthropogenic emissions strongly affect surface BC concentration and AAOD, while the BC aging mainly affects BC in snow over the Plateau.

scholarly journals Wintertime direct radiative effects due to black carbon (BC) over the Indo-Gangetic Plain as modelled with new BC emission inventories in CHIMERE

2021 ◽  
Vol 21 (10) ◽  
pp. 7671-7694
Author(s):  
Sanhita Ghosh ◽  
Shubha Verma ◽  
Jayanarayanan Kuttippurath ◽  
Laurent Menut
Keyword(s):  
Black Carbon ◽  
Transport Model ◽  
Eastern Coast ◽  
Emission Inventories ◽  
Surface Cooling ◽  
Gangetic Plain ◽  
Bottom Up ◽  
Bc Aerosols ◽  
Radiative Perturbation ◽  
Indo Gangetic Plain

Abstract. To reduce the uncertainty in climatic impacts induced by black carbon (BC) from global and regional aerosol–climate model simulations, it is a foremost requirement to improve the prediction of modelled BC distribution, specifically over the regions where the atmosphere is loaded with a large amount of BC, e.g. the Indo-Gangetic Plain (IGP) in the Indian subcontinent. Here we examine the wintertime direct radiative perturbation due to BC with an efficiently modelled BC distribution over the IGP in a high-resolution (0.1∘ × 0.1∘) chemical transport model, CHIMERE, implementing new BC emission inventories. The model efficiency in simulating the observed BC distribution was assessed by executing five simulations: Constrained and bottomup (bottomup includes Smog, Cmip, Edgar, and Pku). These simulations respectively implement the recently estimated India-based observationally constrained BC emissions (Constrainedemiss) and the latest bottom-up BC emissions (India-based: Smog-India; global: Coupled Model Intercomparison Project phase 6 – CMIP6, Emission Database for Global Atmospheric Research-V4 – EDGAR-V4, and Peking University BC Inventory – PKU). The mean BC emission flux from the five BC emission inventory databases was found to be considerably high (450–1000 kg km−2 yr−1) over most of the IGP, with this being the highest (> 2500 kg km−2 yr−1) over megacities (Kolkata and Delhi). A low estimated value of the normalised mean bias (NMB) and root mean square error (RMSE) from the Constrained estimated BC concentration (NMB: < 17 %) and aerosol optical depth due to BC (BC-AOD) (NMB: 11 %) indicated that simulations with Constrainedemiss BC emissions in CHIMERE could simulate the distribution of BC pollution over the IGP more efficiently than with bottom-up emissions. The high BC pollution covering the IGP region comprised a wintertime all-day (daytime) mean BC concentration and BC-AOD respectively in the range 14–25 µg m−3 (6–8 µg m−3) and 0.04–0.08 µg m−3 from the Constrained simulation. The simulated BC concentration and BC-AOD were inferred to be primarily sensitive to the change in BC emission strength over most of the IGP (including the megacity of Kolkata), but also to the transport of BC aerosols over megacity Delhi. Five main hotspot locations were identified in and around Delhi (northern IGP), Prayagraj–Allahabad–Varanasi (central IGP), Patna–Palamu (upper, lower, and mideastern IGP), and Kolkata (eastern IGP). The wintertime direct radiative perturbation due to BC aerosols from the Constrained simulation estimated the atmospheric radiative warming (+30 to +50 W m−2) to be about 50 %–70 % larger than the surface cooling. A widespread enhancement in atmospheric radiative warming due to BC by 2–3 times and a reduction in surface cooling by 10 %–20 %, with net warming at the top of the atmosphere (TOA) of 10–15 W m−2, were noticed compared to the atmosphere without BC, for which a net cooling at the TOA was exhibited. These perturbations were the strongest around megacities (Kolkata and Delhi), extended to the eastern coast, and were inferred to be 30 %–50% lower from the bottomup than the Constrained simulation.

Evaluation of emission strength efficacy in simulating black carbon burden with CHIMERE: estimating wintertime radiative effect over Indo-Gangetic Plain

2020 ◽  
Author(s):  
Sanhita Ghosh ◽  
Shubha Verma ◽  
Jayanarayanan Kuttippurath
Keyword(s):  
Black Carbon ◽  
Transport Model ◽  
Indian Subcontinent ◽  
Chemical Transport ◽  
Climate Impacts ◽  
Eastern Coast ◽  
Spatial And Temporal Patterns ◽  
Gangetic Plain ◽  
Bc Aerosols ◽  
Indo Gangetic Plain

&lt;p&gt;Black carbon (BC) aerosols over the Indian subcontinent have been represented inadequately so-far in chemical transport models restricting the accurate assessment of BC-induced climate impacts. The divergence between simulated and measured BC concentration has specifically been reported to be large over the Indo-Gangetic Plain (IGP) during winter when a large BC burden is observed. In this study, we evaluate the BC transport simulations over the IGP in a high resolution (0.1&amp;#186; &amp;#215; 0.1&amp;#186; ) chemical transport model, CHIMERE. We examine the model efficiency to simulate the observed BC distribution executing five sets of simulation experiments: &lt;em&gt;Constrained &lt;/em&gt;and&lt;em&gt; bottomup&lt;/em&gt; (&lt;em&gt;Smog, Pku, Edgar, Cmip&lt;/em&gt;) implementing respectively, the recently estimated India-based constrained BC emission and the latest bottom-up BC emissions (India-based: Smog-India, and global: Coupled Model Intercomparison Project phase 6 (CMIP6), Emission Database for Global Atmospheric Research-V4 (EDGAR-V4) and Peking University BC Inventory (PKU)). The mean BC emission flux over most of the IGP from the five emission datasets is considerably high (450&amp;#8211;1000 kg km&lt;sup&gt;-2&lt;/sup&gt; y&lt;sup&gt;-1&lt;/sup&gt;) with a relatively low divergence obtained for the eastern and upper-mideastern IGP. Evaluation of BC transport simulations shows that the spatial and temporal gradient in the simulated BC concentration from the &lt;em&gt;Constrained &lt;/em&gt;was equivalent to that from the &lt;em&gt;bottomup&lt;/em&gt; and also to that from observations. This indicates that the spatial and temporal patterns of BC concentration are consistently simulated by the model processes. However, the efficacy to simulate BC distribution is commendable for the estimates from &lt;em&gt;Constrained&lt;/em&gt; for which the lowest normalised mean bias (NMB, &lt; 20%) is obtained in comparison to that from the &lt;em&gt;bottomup&lt;/em&gt; (37&amp;#8211;52%). 75&amp;#8211;100% of the observed all-day (daytime) mean BC concentration is simulated most of the times (&gt;80% of the number of stations data) for &lt;em&gt;Constrained&lt;/em&gt;, whereas, this being less frequent (&lt;50%) for the &lt;em&gt;Pku, Smog, Edgar&lt;/em&gt; and poor for &lt;em&gt;Cmip&lt;/em&gt;. The BC-AOD (0.04&amp;#8211;0.08) estimated from the &lt;em&gt;Constrained&lt;/em&gt; is 20&amp;#8211;50% higher than the &lt;em&gt;Pku&lt;/em&gt; and &lt;em&gt;Smog&lt;/em&gt;. Three main hotspot locations comprising of a large value of BC load are identified over the eastern, mideastern, and northern IGP. Assessment of the effect of BC burden on the wintertime radiative perturbation over the IGP shows that the presence of BC aerosols in the atmosphere enhances atmospheric heating by 2&amp;#8211;3 times more compared to that considering atmosphere without BC. Also, a net warming at the top of the atmosphere (TOA) by 10&amp;#8211;17 W m&lt;sup&gt;-&lt;/sup&gt;&lt;sup&gt;2&lt;/sup&gt; is noticed from the &lt;em&gt;Constrained&lt;/em&gt;, with the largest value estimated in and around megacities (Kolkata and Delhi) that extends to the eastern coast. This value is higher by 10&amp;#8211;20% than that from &lt;em&gt;Cmip&lt;/em&gt; over the IGP and by 2&amp;#8211;10% than that from &lt;em&gt;Smog&lt;/em&gt; over Delhi and eastern part of the IGP.&lt;/p&gt;

scholarly journals Multi-species inversion of CH<sub>4</sub>, CO and H<sub>2</sub> emissions from surface measurements

2009 ◽  
Vol 9 (14) ◽  
pp. 5281-5297 ◽  
Author(s):  
I. Pison ◽  
P. Bousquet ◽  
F. Chevallier ◽  
S. Szopa ◽  
D. Hauglustaine
Keyword(s):  
Transport Model ◽  
Regional Scale ◽  
Surface Concentration ◽  
Temporal Variations ◽  
Global Scale ◽  
Chemical Transport Model ◽  
Methyl Chloroform ◽  
Emission Fluxes ◽  
Surface Measurements ◽  
One Year

Abstract. In order to study the spatial and temporal variations of the emissions of greenhouse gases and of their precursors, we developed a data assimilation system and applied it to infer emissions of CH4, CO and H2 for one year. It is based on an atmospheric chemical transport model and on a simplified scheme for the oxidation chain of hydrocarbons, including methane, formaldehyde, carbon monoxide and molecular hydrogen together with methyl chloroform. The methodology is exposed and a first attempt at evaluating the inverted fluxes is made. Inversions of the emission fluxes of CO, CH4 and H2 and concentrations of HCHO and OH were performed for the year 2004, using surface concentration measurements of CO, CH4, H2 and CH3CCl3 as constraints. Independent data from ship and aircraft measurements and satellite retrievals are used to evaluate the results. The total emitted mass of CO is 30% higher after the inversion, due to increased fluxes by up to 35% in the Northern Hemisphere. The spatial distribution of emissions of CH4 is modified by a decrease of fluxes in boreal areas up to 60%. The comparison between mono- and multi-species inversions shows that the results are close at a global scale but may significantly differ at a regional scale because of the interactions between the various tracers during the inversion.

scholarly journals Black Carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons

2019 ◽  
Author(s):  
James Brooks ◽  
Dantong Liu ◽  
James D. Allan ◽  
Paul I. Williams ◽  
Jim Haywood ◽  
...  
Keyword(s):  
Physical Properties ◽  
Black Carbon ◽  
Mixing State ◽  
Atmospheric Measurements ◽  
Core Diameter ◽  
Gangetic Plain ◽  
North West ◽  
North East ◽  
Northern India ◽  
Indo Gangetic Plain

Abstract. Black carbon (BC) is known to have major impacts on both climate and human health, so is therefore of global importance, particularly so in regions close to large populations that have strong sources. The physical properties and mixing state of black carbon containing particles are important determinants in these effects but information is often lacking, particularly in some of the most important regions of the globe. Detailed analysis into the vertical and horizontal BC optical and physical properties across northern India has been carried out using airborne in-situ measurements. The size-resolved mixing state of BC-containing particles was characterised using a single particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11th and 12th June) and monsoon (30th June to 11th July) seasons of 2016. Over the Indo-Gangetic Plain, BC mass concentrations were greater (1.95 µg/m3) compared to north-west India (1.50 µg/m3) and north-east India (0.70 µg/m3) during the pre-monsoon. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter 

scholarly journals Retrieval of total column and surface NO<sub>2</sub> from Pandora zenith-sky measurements

2019 ◽  
Author(s):  
Xiaoyi Zhao ◽  
Debora Griffin ◽  
Vitali Fioletov ◽  
Chris McLinden ◽  
Jonathan Davies ◽  
...  
Keyword(s):  
Transport Model ◽  
Surface Concentration ◽  
In Situ Measurements ◽  
Radiative Transfer Model ◽  
Retrieval Algorithm ◽  
Transfer Model ◽  
Chemical Transport Model ◽  
High Quality ◽  
Vertical Column

Abstract. Pandora spectrometers can retrieve nitrogen dioxide (NO2) vertical column densities (VCDs) via two viewing geometries: direct-sun and zenith-sky. The direct-sun NO2 VCD measurements have high quality (0.1 DU accuracy in clear-sky conditions) and do not rely on any radiative transfer model to calculate air mass factors (AMFs); however, they are not available when the sun is obscured by clouds. To perform NO2 measurements in cloudy conditions, a simple but robust NO2 retrieval algorithm is developed for Pandora zenith-sky measurements. This algorithm derives empirical zenith-sky NO2 AMFs from coincident high-quality direct-sun NO2 observations. Moreover, the retrieved Pandora zenith-sky NO2 VCD data are converted to surface NO2 concentrations with a scaling algorithm that uses chemical-transport-model predictions and satellite measurements as inputs. NO2 VCDs and surface concentrations are retrieved from Pandora zenith-sky measurements made in Toronto, Canada, from 2015 to 2017. The retrieved Pandora zenith-sky NO2 data (VCD and surface concentration) show good agreement with both satellite and in situ measurements. The diurnal and seasonal variations of derived Pandora zenith-sky surface NO2 data also agree well with in situ measurements (diurnal difference within ±2 ppbv). Overall, this work shows that the new Pandora zenith-sky NO2 products have the potential to be used in various applications such as future satellite validation in moderate cloudy scenes and air quality monitoring.

scholarly journals Development of a grid-independent GEOS-Chem chemical transport model (v9-02) as an atmospheric chemistry module for Earth system models

2015 ◽  
Vol 8 (3) ◽  
pp. 595-602 ◽  
Author(s):  
M. S. Long ◽  
R. Yantosca ◽  
J. E. Nielsen ◽  
C. A. Keller ◽  
A. da Silva ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Chemical Transport ◽  
Earth System ◽  
Chemical Transport Model ◽  
Modeling Framework ◽  
System Models ◽  
Chemistry Research ◽  
Earth System Models ◽  
Chemistry Module

Abstract. The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been re-engineered to also serve as an atmospheric chemistry module for Earth system models (ESMs). This was done using an Earth System Modeling Framework (ESMF) interface that operates independently of the GEOS-Chem scientific code, permitting the exact same GEOS-Chem code to be used as an ESM module or as a stand-alone CTM. In this manner, the continual stream of updates contributed by the CTM user community is automatically passed on to the ESM module, which remains state of science and referenced to the latest version of the standard GEOS-Chem CTM. A major step in this re-engineering was to make GEOS-Chem grid independent, i.e., capable of using any geophysical grid specified at run time. GEOS-Chem data sockets were also created for communication between modules and with external ESM code. The grid-independent, ESMF-compatible GEOS-Chem is now the standard version of the GEOS-Chem CTM. It has been implemented as an atmospheric chemistry module into the NASA GEOS-5 ESM. The coupled GEOS-5–GEOS-Chem system was tested for scalability and performance with a tropospheric oxidant-aerosol simulation (120 coupled species, 66 transported tracers) using 48–240 cores and message-passing interface (MPI) distributed-memory parallelization. Numerical experiments demonstrate that the GEOS-Chem chemistry module scales efficiently for the number of cores tested, with no degradation as the number of cores increases. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemistry module means that the relative cost goes down with increasing number of cores in a massively parallel environment.

scholarly journals Impact of regional climate change and future emission scenarios on surface O<sub>3</sub> and PM<sub>2.5</sub> over India

2018 ◽  
Vol 18 (1) ◽  
pp. 103-127 ◽  
Author(s):  
Matthieu Pommier ◽  
Hilde Fagerli ◽  
Michael Gauss ◽  
David Simpson ◽  
Sumit Sharma ◽  
...  
Keyword(s):  
Climate Change ◽  
Transport Model ◽  
Surface Ozone ◽  
Deposition Velocity ◽  
Public Health Issue ◽  
Anthropogenic Emissions ◽  
Reference Scenario ◽  
Chemical Transport Model ◽  
Data Set ◽  
Gangetic Plain

Abstract. Eleven of the world's 20 most polluted cities are located in India and poor air quality is already a major public health issue. However, anthropogenic emissions are predicted to increase substantially in the short-term (2030) and medium-term (2050) futures in India, especially if no further policy efforts are made. In this study, the EMEP/MSC-W chemical transport model has been used to predict changes in surface ozone (O3) and fine particulate matter (PM2.5) for India in a world of changing emissions and climate. The reference scenario (for present-day) is evaluated against surface-based measurements, mainly at urban stations. The evaluation has also been extended to other data sets which are publicly available on the web but without quality assurance. The evaluation shows high temporal correlation for O3 (r =  0.9) and high spatial correlation for PM2.5 (r =  0.5 and r =  0.8 depending on the data set) between the model results and observations. While the overall bias in PM2.5 is small (lower than 6 %), the model overestimates O3 by 35 %. The underestimation in NOx titration is probably the main reason for the O3 overestimation in the model. However, the level of agreement can be considered satisfactory in this case of a regional model being evaluated against mainly urban measurements, and given the inevitable uncertainties in much of the input data.For the 2050s, the model predicts that climate change will have distinct effects in India in terms of O3 pollution, with a region in the north characterized by a statistically significant increase by up to 4 % (2 ppb) and one in the south by a decrease up to −3 % (−1.4 ppb). This variation in O3 is assumed to be partly related to changes in O3 deposition velocity caused by changes in soil moisture and, over a few areas, partly also by changes in biogenic non-methane volatile organic compounds.Our calculations suggest that PM2.5 will increase by up to 6.5 % over the Indo-Gangetic Plain by the 2050s. The increase over India is driven by increases in dust, particulate organic matter (OM) and secondary inorganic aerosols (SIAs), which are mainly affected by the change in precipitation, biogenic emissions and wind speed.The large increase in anthropogenic emissions has a larger impact than climate change, causing O3 and PM2.5 levels to increase by 13 and 67 % on average in the 2050s over the main part of India, respectively. By the 2030s, secondary inorganic aerosol is predicted to become the second largest contributor to PM2.5 in India, and the largest in the 2050s, exceeding OM and dust.

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