Unusual enhancement in tropospheric and surface ozone due to orography induced gravity waves

Phanikumar, D. V.; Kumar, Kondapalli Niranjan; Bhattacharjee, Samaresh; Naja, Manish; Girach, Imran A.; Nair, Prabha R.; Kumari, Shweta

doi:10.1016/j.rse.2017.07.011

Cited by 9 publications

(4 citation statements)

References 57 publications

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“…These contrasting variations tend to show the negative correlations. However, a slight positive correlation is observed around noon (13:00-15:00 h), which is similar to what is generally observed at high-altitude sites (Kajii et al, 1998;Tsutsumi and Matsueda, 2000;Naja et al, 2003;Sarangi et al, 2014) and cleaner sites (e.g., island sites; Pochanart et al, 1999).…”

Section: Correlation Between Ozone and Cosupporting

confidence: 82%

Variations in surface ozone and carbon monoxide in the Kathmandu Valley and surrounding broader regions during SusKat-ABC field campaign: role of local and regional sources

et al. 2018

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Abstract. Air pollution resulting from rapid urbanization and associated human activities in the Kathmandu Valley of Nepal has been leading to serious public health concerns over the past 2 decades. These concerns led to a multinational field campaign SusKat-ABC (Sustainable atmosphere for the Kathmandu Valley – Atmospheric Brown Clouds) that measured different trace gases, aerosols and meteorological parameters in the Kathmandu Valley and surrounding regions during December 2012 to June 2013 to understand local- to regional-scale processes influencing air quality of the Kathmandu Valley. This study provides information about the regional distribution of ozone and some precursor gases using simultaneous in situ measurements from a SusKat-ABC supersite at Bode, Nepal, and two Indian sites: a high-altitude site, Nainital, located in the central Himalayan region and a low-altitude site, Pantnagar, located in the Indo-Gangetic Plain (IGP). The diurnal variations at Bode showed a daytime buildup in O3 while CO shows morning and evening peaks. Similar variations (with lower levels) were also observed at Pantnagar but not at Nainital. Several events of hourly ozone levels exceeding 80 ppbv were also observed at Bode. The CO levels showed a decrease from their peak level of about 2000 ppbv in January to about 680 ppbv in June at Bode. The hourly mean ozone and CO levels showed a strong negative correlation during winter (r2 = 0.82 in January and r2 = 0.71 in February), but this negative correlation gradually becomes weaker, with the lowest value in May (r2 = 0.12). The background O3 and CO mixing ratios at Bode were estimated to be about 14 and 325 ppbv, respectively. The rate of change of ozone at Bode showed a more rapid increase ( ∼ 17 ppbv h−1) during morning than the decrease in the evening (5–6 ppbv h−1), suggesting the prevalence of a semi-urban environ. The lower CO levels during spring suggest that regional transport also contributes appreciably to springtime ozone enhancement in the Kathmandu Valley on top of the local in situ ozone production. We show that regional pollution resulting from agricultural crop residue burning in northwestern IGP led to simultaneous increases in O3 and CO levels at Bode and Nainital during the first week of May 2013. A biomass-burning-induced increase in ozone and related gases was also confirmed by a global model and balloon-borne observations over Nainital. A comparison of surface ozone variations and composition of light non-methane hydrocarbons among different sites indicated the differences in emission sources of the Kathmandu Valley and the IGP. These results highlight that it is important to consider regional sources in air quality management of the Kathmandu Valley.

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Section: Correlation Between Ozone and Cosupporting

confidence: 82%

Variations in surface ozone and carbon monoxide in the Kathmandu Valley and surrounding broader regions during SusKat-ABC field campaign: role of local and regional sources

et al. 2018

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“…The cyclones above 15°N experience a higher orography, whereas those below 15°N experience a lower orography. Tropospheric ozone enhancement from tropopause folding due to orography-induced waves generated from wind flow over the Himalayan region has also been reported earlier (Niranjan Kumar et al, 2012;Phanikumar et al, 2017). The cumulative effect of the Himalayas in northern India (25°-40°N and 70°-100°E) and an NIO cyclone can lead to more intense stratospheric intrusion; such an analysis is beyond the scope of this study.…”

Section: Discussionsupporting

confidence: 71%

“…Waves triggered by orography, like the Himalayas, can also lead to oscillations in the wind flow and reach the upper atmosphere (Kaifler et al., 2015; Lyapustin et al., 2014; Niranjan Kumar et al., 2012). Such orography‐induced waves can lead to STE and ozone enhancement over the Himalayas (K. N. Kumar et al., 2020; Phanikumar et al., 2017). Upper tropospheric ozone enhancement over India during tropical cyclones via stratospheric intrusions has been studied earlier (Das et al., 2011; Das et al., 2016a; Das et al., 2016b).…”

Section: Resultsmentioning

confidence: 99%

Estimation of Stratospheric Intrusions During Indian Cyclones

et al. 2023

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Deep convection associated with tropical cyclones leads to stratosphere‐troposphere exchange (STE), which affects the upper‐tropospheric ozone concentrations in the vicinity of the cyclones. This study estimates the ozone enhancements over India due to the North Indian Ocean (NIO) cyclones‐driven STE. Indicators such as stratospheric fraction and potential vorticity calculated using the reanalysis data sets suggest that roughly 70% of the cyclones show anomalously high stratospheric intrusions. Aircraft observations over different locations across India also show elevated ozone concentrations in the mid‐to‐upper troposphere on cyclone days. Further, ozone and stratospheric ozone tracer concentrations from Goddard Earth Observing System‐Chemistry simulations and the Copernicus Atmosphere Monitoring Service reanalysis data sets show up to 40 ppb of excess upper tropospheric ozone over India, of which stratospheric ozone accounts for roughly 60%. Stratospheric intrusion due to the Bay of Bengal and the Arabian Sea cyclones affected the upper tropospheric ozone amounts over North and South India, respectively. The stratospheric ozone was observed to propagate downwards into the troposphere, often reaching ∼600 hPa and, in some cases, even the surface.

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“…This phenomenon is widely believed to be because of the formation of strong polar eddies on the Antarctic continent that impede ozone transport from the equator to polar regions [24,25]. This is usually coupled with stratospheric clouds formed by strong polar vortices that bring halogenic elements into the stratosphere and accelerate ozone depletion [26]. Eddies formed in the Antarctic region can be observed regarding temperature and pressure [27].…”

Section: Introductionmentioning

confidence: 99%

Unusual Enhancement of the Optical Depth on the Continental Shelf Depth Latitudinal Variation in the Stratospheric Polar Vortex

Qian

Yang

et al. 2023

Remote Sensing

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The Antarctic ozone hole has attracted attention concerning global climate change. Breakthroughs regarding ozone observation methods and the formation principles of ozone holes have occurred. This study compared the slant column ozone obtained from SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) Level 1 optical spectroscopy data processed by QDOAS software with that reconstructed from SCIAMACHY Level 2 ozone data using geographic information to obtain the optical depth coefficients. The global distribution of optical depth coefficients reveals latitudinal homogeneity, whereas the distribution of coefficients in the polar regions reveals heterogeneity. This heterogeneity has an annual variation pattern, alternating between strong and weak distributions in the Arctic and Antarctic regions. It is most evident in the Palmer Peninsula of Antarctica, where the optical depth coefficients were significantly higher than those of the surrounding regions at the same latitude. This analysis excluded the atmospheric pressure influence and suggested the influence of the continental shelf depth. The protrusion of the continental shelf depth changes the optical depth coefficients owing to the geographical proximity of the Antarctic Palmer Peninsula to South America, which separates the Atlantic and Pacific Oceans in an east–west direction.

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Unusual enhancement in tropospheric and surface ozone due to orography induced gravity waves

Cited by 9 publications

References 57 publications

Variations in surface ozone and carbon monoxide in the Kathmandu Valley and surrounding broader regions during SusKat-ABC field campaign: role of local and regional sources

Variations in surface ozone and carbon monoxide in the Kathmandu Valley and surrounding broader regions during SusKat-ABC field campaign: role of local and regional sources

Estimation of Stratospheric Intrusions During Indian Cyclones

Unusual Enhancement of the Optical Depth on the Continental Shelf Depth Latitudinal Variation in the Stratospheric Polar Vortex

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