@article{uttamang_campbell_aneja_hanna_2020, title={A multi-scale model analysis of ozone formation in the Bangkok Metropolitan Region, Thailand}, volume={229}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85083337226&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2020.117433}, abstractNote={Over the last three decades, Thailand's rapid industrialization and urbanization have led to an impact on urban air quality. A majority of the country's development has occurred within and around Bangkok (BKK), the capital city of Thailand, and the Bangkok Metropolitan Region (BMR). Since 1995, the BMR has experienced air quality degradation, in particular, enhanced ozone (O3) due to a combination of the local increase in emissions from accelerated growth in automotive and industrial activities, local meteorology including strong solar radiation, high temperature and high humidity, and potential long-range effects of regional transport from China. To investigate the O3 formation in the BMR due to the effects of long-range transport and local meteorology feedbacks, we perform a multi-scale simulation with the Weather Research and Forecasting model with Chemistry (WRF-Chem) during the O3 season (January to March), 2010; since O3 mixing ratio exceedances in the BMR occur primarily during this period The results in this study indicate the significance of China's emission reductions on the regional-scale and the local-scale pollution, as far as the BMR region and southern Thailand. Applying China's oxide of nitrogen (NOx)-only emission controls, generally, enhance the domain-wide monthly-average peroxyacetyl nitrate (PAN) and O3 in the regional scale, in the order of ~1–7% and ~1–5%, respectively, while those in the local scale are ~ 0.2–6% and ~0.1–5% compared with the baseline simulation. However, the increases in PAN and O3 are mitigated by 40% China's Volatile Organic Compound (VOC) reduction along with 40% NOx reduction. The results, supported by an indicator analysis, suggest that northern and eastern China, northern and central Thailand and the BMR, are likely VOC-limited during the O3 season. Since the BMR is VOC-limited regime, controlling anthropogenic VOC emissions will show more benefit to control O3 than controlling NOx-only emissions. Other factors that influence on O3 levels in the BMR are biogenic VOC emissions from the Tenasserim range and land- and sea-breeze circulations that recirculate and disperse pollutants along the coastal areas.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Uttamang, Pornpan and Campbell, Patrick C. and Aneja, Viney P. and Hanna, Adel F.}, year={2020}, month={May} }
 @article{uttamang_aneja_hanna_2018, title={Assessment of gaseous criteria pollutants in the Bangkok Metropolitan Region, Thailand}, volume={18}, ISSN={["1680-7324"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052819254&partnerID=MN8TOARS}, DOI={10.5194/acp-18-12581-2018}, abstractNote={Abstract. The analysis of gaseous criteria pollutants in the Bangkok
Metropolitan Region (BMR), Thailand, from 2010 to 2014 reveals that while the
hourly concentrations of CO, SO2 and NO2 were mostly
within the National Ambient Air Quality Standards (NAAQs) of Thailand, the
hourly concentrations of O3 frequently exceeded the standard. The
results reveal that the problem of high O3 concentration
continuously persisted in this area. The O3 photolytic rate
constant (j1) for BMR calculated based on assuming a photostationary
state ranged from 0.008 to 0.013 s−1, which is similar to the
calculated j1 using the NCAR TUV model (0.021±0.0024 s−1).
Interconversion between O3, NO and NO2 indicates that
crossover points between the species occur when the concentration of
NOx (= NO + NO2) is ∼60 ppb. Under a
low-NOx regime ([NOx] < 60 ppb),
O3 is the dominant species, while, under a
high-NOx regime ([NOx]
> 60 ppb), NO dominates. Linear regression analysis between the
concentrations of Ox (= O3 + NO2)
and NOx provides the role of local and regional
contributions to Ox. During O3 episodes
([O3]hourly > 100 ppb), the values of the
local and regional contributions were nearly double of those during
non-episodes. Ratio analysis suggests that the major contributors of primary
pollutants over BMR are mobile sources. The air quality index (AQI) for BMR
was predominantly good to moderate; however, unhealthy O3
categories were observed during episode conditions in the region.
                    }, number={16}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Uttamang, Pornpan and Aneja, Viney P. and Hanna, Adel F.}, year={2018}, month={Aug}, pages={12581–12593} }
 @article{aneja_brittig_kim_hanna_2004, title={Ozone and other air quality-related variables affecting visibility in the southeast United States}, volume={54}, ISSN={["2162-2906"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2942525221&partnerID=MN8TOARS}, DOI={10.1080/10473289.2004.10470939}, abstractNote={Abstract An analysis of ozone (O3) concentrations and several other air quality-related variables was performed to elucidate their relationship with visibility at five urban and semi-urban locations in the southeast United States during the summer seasons of 1980-1996. The role and impact of O3 on aerosols was investigated to ascertain a relationship with visibility. Regional trend analysis over the 1980s reveals an increase in maximum O3 concentration coupled with a decrease in visibility. However, a similar analysis for the 1990s shows a leveling-off of both O3 and visibility; in both cases, the results were not statistically significant at the 5% level. A case study of site-specific trends at Nashville, TN, followed similar trends. To better understand the relationships between O3 concentration and visibility, the analysis was varied from yearly through daily to hourly averaged values. This increased temporal resolution showed a statistically significant inverse relationship between visibility and O3. Site-specific hourly r2 values ranged from 0.02 to 0.43. Additionally, by performing back-trajectory analysis, it was found that the visibility degraded by air mass migration over polluted areas.}, number={6}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Aneja, VP and Brittig, JS and Kim, DS and Hanna, A}, year={2004}, month={Jun}, pages={681–688} }
 @article{alapaty_seaman_niyogi_hanna_2001, title={Assimilating surface data to improve the accuracy of atmospheric boundary layer simulations}, volume={40}, ISSN={["0894-8763"]}, DOI={10.1175/1520-0450(2001)040<2068:ASDTIT>2.0.CO;2}, abstractNote={Large errors in atmospheric boundary layer (ABL) simulations can be caused by inaccuracies in the specification of surface characteristics in addition to assumptions and simplifications made in boundary layer formulations or other model deficiencies. For certain applications, such as air quality studies, these errors can have significant effects. To reduce such errors, a continuous surface data assimilation technique is developed. In this technique, surface-layer temperature and water vapor mixing ratio are directly assimilated by using the analyzed surface data. Then, the difference between the observations and model results is used to calculate adjustments to the surface fluxes of sensible and latent heat. These adjustments are then used to calculate a new estimate of the ground temperature, thereby affecting the simulated surface fluxes on the subsequent time step. This indirect data assimilation is applied simultaneously with the direct assimilation of surface data in the model’s lowest layer, thereby maintaining greater consistency between the ground temperature and the surface-layer mass-field variables. A one-dimensional model was used to study the improvements that result from applying this technique for ABL simulations in two cases. It was found that application of the new technique led to significant reductions in ABL modeling errors.}, number={11}, journal={JOURNAL OF APPLIED METEOROLOGY}, author={Alapaty, K and Seaman, NL and Niyogi, DS and Hanna, AF}, year={2001}, pages={2068–2082} }