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 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.

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.

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.

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 Enhanced trans-Himalaya pollution transport to the Tibetan Plateau by cut-off low systems

2017 ◽  
Vol 17 (4) ◽  
pp. 3083-3095 ◽  
Author(s):  
Ruixiong Zhang ◽  
Yuhang Wang ◽  
Qiusheng He ◽  
Laiguo Chen ◽  
Yuzhong Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Black Carbon ◽  
Long Range ◽  
Radiative Forcing ◽  
Long Range Transport ◽  
The Tibetan Plateau ◽  
Pollution Transport ◽  
Top Down ◽  
Gangetic Plain ◽  
Range Transport

Abstract. Long-range transport followed by deposition of black carbon on glaciers of Tibet is one of the key issues of climate research as it induces changes on radiative forcing and subsequently impacting the melting of glaciers. The transport mechanism, however, is not well understood. In this study, we use short-lived reactive aromatics as proxies to diagnose transport of pollutants to Tibet. In situ observations of short-lived reactive aromatics across the Tibetan Plateau are analyzed using a regional chemistry and transport model. The model performance using the current emission inventories over the region is poor due to problems in the inventories and model transport. Top-down emissions constrained by satellite observations of glyoxal are a factor of 2–6 higher than the a priori emissions over the industrialized Indo-Gangetic Plain. Using the top-down emissions, agreement between model simulations and surface observations of aromatics improves. We find enhancements of reactive aromatics over Tibet by a factor of 6 on average due to rapid transport from India and nearby regions during the presence of a high-altitude cut-off low system. Our results suggest that the cut-off low system is a major pathway for long-range transport of pollutants such as black carbon. The modeling analysis reveals that even the state-of-the-science high-resolution reanalysis cannot simulate this cut-off low system accurately, which probably explains in part the underestimation of black carbon deposition over Tibet in previous modeling studies. Another model deficiency of underestimating pollution transport from the south is due to the complexity of terrain, leading to enhanced transport. It is therefore challenging for coarse-resolution global climate models to properly represent the effects of long-range transport of pollutants on the Tibetan environment and the subsequent consequence for regional climate forcing.

Highlighting Uncertainty and Recommendations for Improvement of Black Carbon Biomass Fuel-Based Emission Inventories in the Indo-Gangetic Plain Region

2016 ◽  
Vol 3 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Sutyajeet I. Soneja ◽  
James M. Tielsch ◽  
Subarna K. Khatry ◽  
Frank C. Curriero ◽  
Patrick N. Breysse
Keyword(s):  
Black Carbon ◽  
Biomass Fuel ◽  
Emission Inventories ◽  
Gangetic Plain ◽  
Carbon Biomass ◽  
Plain Region ◽  
Indo Gangetic Plain

scholarly journals Enhanced Trans-Himalaya Pollution Transport to the Tibetan Plateau by the Cut-off Low System

2016 ◽  
Author(s):  
Ruixiong Zhang ◽  
Yuhang Wang ◽  
Qiusheng He ◽  
Laiguo Chen ◽  
Yuzhong Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Black Carbon ◽  
Long Range ◽  
Radiative Forcing ◽  
Long Range Transport ◽  
The Tibetan Plateau ◽  
Pollution Transport ◽  
Top Down ◽  
Gangetic Plain ◽  
Range Transport

Abstract. Long-range transport and subsequent deposition of black carbon on glaciers of Tibet is one of the key issues of climate research inducing changes on radiative forcing and subsequently impacting on the melting of glaciers. The transport mechanism, however, is not well understood. In this study, we use short-lived reactive aromatics as proxies to diagnose transport of pollutants to Tibet. In situ observations of short-lived reactive aromatics across the Tibetan Plateau are analyzed using a regional chemistry and transport model. The model performance using the current emission inventories over the region is poor due to problems in the inventories and model transport. Top-down emissions constrained by satellite observations of glyoxal (CHOCHO) are a factor of 2–6 higher than the a priori emissions over the industrialized Indo-Gangetic Plain. Using the top-down emissions, agreement between model simulations and surface observations of aromatics improves. We find enhancements of reactive aromatics over Tibet by a factor of 6 on average due to rapid transport from India and nearby regions during the presence of a high-altitude cut-off low system. Our results suggest that the cut-off low system is a major pathway for long-range transport of pollutants such as black carbon. The modeling analysis reveals that even the state-of-the-science high-resolution reanalysis cannot simulate this cut-off low system accurately, which probably explains in part the underestimation of black carbon deposition over Tibet in previous modeling studies. Furthermore, another model deficiency of underestimating pollution transport from the south is due to the complexity of terrain, leading to enhanced transport. It is therefore challenging for coarse-resolution global climate models to properly represent the effects of long-range transport of pollutants on the Tibetan environment and the subsequent consequence for regional climate forcing.

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