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3. Air Pollution Modeling

Author

Yadav, Ravi, Trivedi, Pujal, Sahu, L. K., Beig, G., Tripathi, Nidhi, Lichtfouse, Eric, Series Editor, Schwarzbauer, Jan, Series Editor, Robert, Didier, Series Editor, Saxena, Pallavi, editor, and Srivastava, Anju, editor

Published
2020
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12. Characteristics of VOC Composition at Urban and Suburban Sites of New Delhi, India in Winter

Author

Tripathi, Nidhi, primary, Sahu, L. K., additional, Wang, Liwei, additional, Vats, Pawan, additional, Soni, Meghna, additional, Kumar, Purushottam, additional, Satish, R. V., additional, Bhattu, Deepika, additional, Sahu, Ravi, additional, Patel, Kashyap, additional, Rai, Pragati, additional, Kumar, Varun, additional, Rastogi, Neeraj, additional, Ojha, Narendra, additional, Tiwari, Shashi, additional, Ganguly, Dilip, additional, Slowik, Jay, additional, Prévôt, André S. H., additional, and Tripathi, Sachchida N., additional

Published
2022
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26. Seasonal and interannual variability of carbon monoxide based on MOZAIC observations, MACC reanalysis, and model simulations over an urban site in India

Author

Sheel, Varun, Sahu, L. K., Kajino, M., Deushi, M., Stein, O., and Nedelec, P.

Subjects
ddc:550
Abstract

The spatial and temporal variations of carbon monoxide (CO) are analyzed over a tropical urban site, Hyderabad (17°27′N, 78°28′E) in central India. We have used vertical profiles from the Measurement of ozone and water vapor by Airbus in-service aircraft (MOZAIC) aircraft observations, Monitoring Atmospheric Composition and Climate (MACC) reanalysis, and two chemical transport model simulations (Model for Ozone And Related Tracers (MOZART) and MRI global Chemistry Climate Model (MRI-CCM2)) for the years 2006–2008. In the lower troposphere, the CO mixing ratio showed strong seasonality, with higher levels (>300 ppbv) during the winter and premonsoon seasons associated with a stable anticyclonic circulation, while lower CO values (up to 100 ppbv) were observed in the monsoon season. In the planetary boundary layer (PBL), the seasonal distribution of CO shows the impact of both local meteorology and emissions. While the PBL CO is predominantly influenced by strong winds, bringing regional background air from marine and biomass burning regions, under calm conditions CO levels are elevated by local emissions. On the other hand, in the free troposphere, seasonal variation reflects the impact of long-range transport associated with the Intertropical Convergence Zone and biomass burning. The interannual variations were mainly due to transition from El Niño to La Niña conditions. The overall modified normalized mean biases (normalization based on the observed and model mean values) with respect to the observed CO profiles were lower for the MACC reanalysis than the MOZART and MRI-CCM2 models. The CO in the PBL region was consistently underestimated by MACC reanalysis during all the seasons, while MOZART and MRI-CCM2 show both positive and negative biases depending on the season.

Published
2014
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27. Characteristics of tropospheric ozone variability over an urban site in Southeast Asia: A study based on MOZAIC and MOZART vertical profiles

Author

Sahu, L. K., Sheel, Varun, Kajino, M., Gunthe, Sachin S., Thouret, Valérie, Nedelec, P., and Smit, Herman G.

Subjects
biomass burning, long range forecast, boundary layer, Tropospheric ozone, carbon monoxide, mixing ratio, Central Region [Thailand], Ozone, trace gas, Mixing, MOZAIC, ddc:550, Biomass, convection, seasonal variation, aircraft emission, Troposphere, Krung Thep Mahanakhon, Thailand, Southeast Asia, Biomass-burning, vertical profile, Bangkok, Indonesia, trajectory, air mass, urban, aircraft, urban site, El Nino
Abstract

The Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) profiles of O3 and CO were analyzed to study their variation in the troposphere over Bangkok. Mixing ratios of O3 and CO were enhanced in planetary boundary layer (PBL) being highest in winter followed by summer and wet seasons. The daytime profiles of O3 show higher values compared to nighttime observations in PBL region, but little differences were observed in the free troposphere. The decreasing mixing ratios of O3 in the lower and upper troposphere were associated with shallow and deep convections, respectively. Back trajectory and fire count data indicate that the seasonal variations in trace gases were caused mainly by the regional shift in long-range transport and biomass-burning patterns. In wet season, flow of oceanic air and negligible presence of local biomass burning resulted in lowest O3 and CO, while their high levels in dry season were due to extensive biomass burning and transport of continental air masses. The Model for Ozone and Related Chemical Tracers (MOZART) underestimated both O3 and CO in the PBL region but overestimated these in the free troposphere. Simulations of O3 and CO also show the daytime/nighttime differences but do not capture several key features observed in the vertical distributions. The observed and simulated values of O3 and CO during September-November 2006 were significantly higher than the same period of 2005. The year-to-year differences were mainly due to El Ni�o-led extensive fires in Indonesia during 2006 but normal condition during 2005. Key Points Seasonal and year-to-year variations in vertical tropospheric ozone over Bangkok Impact of biomass burning in S-SE Asia during El Nino year 2006 Comparison of aircraft vertical profiles of ozone and CO with MOZART simulations �2013. American Geophysical Union. All Rights Reserved.

Published
2013
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28. Evaluating Model Parameterizations of Submicron Aerosol Scattering and Absorption with In Situ Data from ARCTAS 2008

Author

Alvarado, M. J., primary, Lonsdale, C. R., additional, Macintyre, H. L., additional, Bian, H., additional, Chin, M., additional, Ridley, D. A., additional, Heald, C. L., additional, Thornhill, K. L., additional, Anderson, B. E., additional, Cubison, M. J., additional, Jimenez, J. L., additional, Kondo, Y., additional, Sahu, L. K., additional, Dibb, J. E., additional, and Wang, C., additional

Published
2016
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29. Supplementary material to "Evaluating Model Parameterizations of Submicron Aerosol Scattering and Absorption with In Situ Data from ARCTAS 2008"

Author

Alvarado, M. J., primary, Lonsdale, C. R., additional, Macintyre, H. L., additional, Bian, H., additional, Chin, M., additional, Ridley, D. A., additional, Heald, C. L., additional, Thornhill, K. L., additional, Anderson, B. E., additional, Cubison, M. J., additional, Jimenez, J. L., additional, Kondo, Y., additional, Sahu, L. K., additional, Dibb, J. E., additional, and Wang, C., additional

Published
2016
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34. Emission characteristics of black carbon in anthropogenic and biomass burning plumes over California during ARCTAS‐CARB 2008

Author

Sahu, L. K., primary, Kondo, Y., additional, Moteki, N., additional, Takegawa, N., additional, Zhao, Y., additional, Cubison, M. J., additional, Jimenez, J. L., additional, Vay, S., additional, Diskin, G. S., additional, Wisthaler, A., additional, Mikoviny, T., additional, Huey, L. G., additional, Weinheimer, A. J., additional, and Knapp, D. J., additional

Published
2012
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37. Accumulation-mode aerosol number concentrations in the Arctic during the ARCTAS aircraft campaign: Long-range transport of polluted and clean air from the Asian continent

Author

Matsui, H., primary, Kondo, Y., additional, Moteki, N., additional, Takegawa, N., additional, Sahu, L. K., additional, Koike, M., additional, Zhao, Y., additional, Fuelberg, H. E., additional, Sessions, W. R., additional, Diskin, G., additional, Anderson, B. E., additional, Blake, D. R., additional, Wisthaler, A., additional, Cubison, M. J., additional, and Jimenez, J. L., additional

Published
2011
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47. Evaluating Model Parameterizations of Submicron Aerosol Scattering and Absorption with In Situ Data from ARCTAS 2008.

Author

Alvarado, M. J., Lonsdale, C. R., Macintyre, H. L., Bian, H., Chin, M., Ridley, D. A., Heald, C. L., Thornhill, K. L., Anderson, B. E., Cubison, M. J., Jimenez, J. L., Kondo, Y., Sahu, L. K., Dibb, J. E., and Wang, C.

Abstract

Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution is used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10-23%, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding in situ size distribution information, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction throughout the aerosol size distribution. Using a core-shell mixing state in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for time-varying mixing states in future versions of ASP. [ABSTRACT FROM AUTHOR]

Published
2016
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50. Temporal variation of elemental carbon in Guangzhou, China, in summer 2006.

Author

Verma, R. L., Sahu, L. K., Kondo, Y., Takegawa, N., Han, S., Jung, J. S., Kim, Y. J., Fan, S., Sugimoto, N., Shammaa, M. H., Zhang, Y. H., and Zhao, Y.

Abstract

In situ measurements of the mass concentration of elemental carbon (EC) and mixing ratios of carbon monoxide (CO) and carbon dioxide (CO2) were made at Guangzhou, an urban measurement site in the Pearl River Delta (PRD), China, in July 2006. The average±standard deviation (SD) concentrations of EC, CO, and CO2 were 4.7±2.3 μgCm-3, 798±459 ppbv and 400±13 ppmv, respectively. The trends of these species were mainly controlled by synoptic-scale changes in meteorology during the campaign. Based on back trajectories, data are analyzed separately for two different air mass types representing northerly and southerly flows. Northerly air masses, constituting about 25% of the campaign, were mainly impacted by stagnant conditions, resulting in elevated levels of pollutants. On the other hand, southerly air masses measured during most of the campaign were mostly influenced by clean marine air. The diurnal patterns of EC, CO, and CO2 exhibited peak concentrations during the morning and evening hours coinciding with rush-hour traffic. The diurnal variations of EC and ΔEC/ΔCO closely followed the traffic pattern of heavy-duty vehicles (HDV) in Guangzhou, similar to that observed in Beijing. The level of EC in this campaign was similar to values reported during previous studies at other sites surrounding Guangzhou. The average slopes of ΔEC/ΔCO, ΔEC/ΔCO2, and ΔCO/ΔCO2 were 0.0054 μgCm-3/ppbv, 0.15 μgCm-3/ppmv, and 46.4 ppbv/ppmv, respectively, agreeing reasonably well with their respective emission ratios derived from regional emission inventories. [ABSTRACT FROM AUTHOR]

Published
2009
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