scholarly journals Simulations over South Asia using the weather research and forecasting model with chemistry (WRF-Chem): chemistry evaluation and initial results

2012 ◽  
Vol 5 (1) ◽  
pp. 1-66 ◽  
Author(s):  
R. Kumar ◽  
M. Naja ◽  
G. G. Pfister ◽  
M. C. Barth ◽  
C. Wiedinmyer ◽  
...  
Keyword(s):  
South Asia ◽  
Biomass Burning ◽  
Surface Ozone ◽  
Ozone Production ◽  
Weather Research And Forecasting ◽  
Northern India ◽  
Vertical Distributions ◽  
Spatio Temporal ◽  
First Time ◽  
Vertical Ozone

Abstract. This study presents annual simulations of tropospheric ozone and related species made for the first time using the WRF-Chem model over South Asia for the year 2008. The model simulated ozone, CO, and NOx are evaluated against ground-based, balloon-borne and satellite-borne (TES, OMI and MOPITT) observations. The comparison of model results with surface ozone observations from seven sites and CO and NOx observations from three sites, indicate the model's ability in reproducing seasonal variations of ozone and CO, but show some differences in NOx. The modeled vertical ozone distribution agrees well with the ozone soundings data from two Indian sites. The vertical distributions of TES ozone and MOPITT CO are generally well reproduced, but the model underestimates TES ozone, OMI tropospheric column NO2 and MOPITT total column CO retrievals during all the months except MOPITT retrievals during August–January. Largest differences between modeled and satellite retrieved quantities are found during spring when intense biomass burning activity occurs in this region. The evaluation results indicate large uncertainties in anthropogenic and biomass burning emission estimates, especially for NOx. The model results indicate clear regional differences in the seasonality of surface ozone over South Asia with estimated net ozone production during daytime (11:30–15:30 h) over inland regions of 0–5 ppbv h−1 during all seasons and of 0–2 ppbv h−1 over marine regions during outflow periods. The model results indicate that ozone production in this region is mostly NOx-limited. This study shows that WRF-Chem model captures many important features of the observations and gives confidence to using the model for understanding the spatio-temporal variability of ozone over South Asia. However, improvements of South Asian emission inventories and simulations at finer model resolution, especially over the complex Himalayan terrain in Northern India, are also essential for accurately simulating ozone in this region.

scholarly journals Simulations over South Asia using the Weather Research and Forecasting model with Chemistry (WRF-Chem): chemistry evaluation and initial results

2012 ◽  
Vol 5 (3) ◽  
pp. 619-648 ◽  
Author(s):  
R. Kumar ◽  
M. Naja ◽  
G. G. Pfister ◽  
M. C. Barth ◽  
C. Wiedinmyer ◽  
...  
Keyword(s):  
South Asia ◽  
Biomass Burning ◽  
Surface Ozone ◽  
Ozone Production ◽  
Weather Research And Forecasting ◽  
Northern India ◽  
Vertical Distributions ◽  
Spatio Temporal ◽  
First Time ◽  
Vertical Ozone

Abstract. This study presents annual simulations of tropospheric ozone and related species made for the first time using the WRF-Chem model over South Asia for the year 2008. The model-simulated ozone, CO, and NOx are evaluated against ground-based, balloon-borne and satellite-borne (TES, OMI and MOPITT) observations. The comparison of model results with surface ozone observations from seven sites and CO and NOx observations from three sites indicate the model's ability in reproducing seasonal variations of ozone and CO, but show some differences in NOx. The modeled vertical ozone distribution agrees well with the ozone soundings data from two Indian sites. The vertical distributions of TES ozone and MOPITT CO are generally well reproduced, but the model underestimates TES ozone, OMI tropospheric column NO2 and MOPITT total column CO retrievals during all the months, except MOPITT retrievals during August–January and OMI retrievals during winter. Largest differences between modeled and satellite-retrieved quantities are found during spring when intense biomass burning activity occurs in this region. The evaluation results indicate large uncertainties in anthropogenic and biomass burning emission estimates, especially for NOx. The model results indicate clear regional differences in the seasonality of surface ozone over South Asia, with estimated net ozone production during daytime (1130–1530 h) over inland regions of 0–5 ppbv h−1 during all seasons and of 0–2 ppbv h−1 over marine regions during outflow periods. The model results indicate that ozone production in this region is mostly NOx-limited. This study shows that WRF-Chem model captures many important features of the observations and gives confidence to using the model for understanding the spatio-temporal variability of ozone over South Asia. However, improvements of South Asian emission inventories and simulations at finer model resolution, especially over the complex Himalayan terrain in northern India, are also essential for accurately simulating ozone in this region.

scholarly journals Contrasting aerosol trends over South Asia during the last decade based on MODIS observations

2011 ◽  
Vol 4 (4) ◽  
pp. 5275-5323 ◽  
Author(s):  
D. G. Kaskaoutis ◽  
S. K. Kharol ◽  
P. R. Sinha ◽  
R. P. Singh ◽  
K. V. S. Badarinath ◽  
...  
Keyword(s):  
South Asia ◽  
Atmospheric Aerosols ◽  
Specific Region ◽  
Gangetic Plains ◽  
Northern India ◽  
Increasing Trend ◽  
Monsoon System ◽  
Spatio Temporal ◽  
Terra Modis ◽  
Aerosol Properties

Abstract. Atmospheric aerosols over south Asia constitute a major environmental and climate issue. Thus, extensive land and cruise campaigns have been conducted over the area focusing on investigating the aerosol properties and climate implications. Except from the ground-based instrumentation, several studies dealt with analyzing the aerosol properties from space, focusing mainly on the spatial distribution of the aerosol optical depth (AOD) and possible feedbacks of aerosols on the monsoon system. However, except from some works using ground-based instrumentation or satellite observations over a specific region, there is lack of studies dealing with monitoring of the aerosol trend over south Asia. The present work analyzes the variations and trends in aerosol load over south Asia using Terra-MODIS AOD550 data in the period 2000–2009. Overall, an increasing trend of 10.17 % in AOD is found over whole south Asia, which exhibits large spatio-temporal variation. More specifically, the AOD550 increasing trend is more pronounced in winter, and especially over northern India. The present study shows an evidence of a decreasing AOD550 trend over the densely-populated Indo-Gangetic Plains (IGP) during the period April–September, which has never been reported before. This decreasing trend is not statistically significant and leads to an AOD change of −0.01 per year in June, when the dust activity is at its maximum. The AOD decrease seems to be attributed to weakness of dust activity in the northwest of India, closely associated with expansion of the vegetated areas and increase in precipitation over the Thar desert. Similarly, GOCART simulations over south Asia show a pronounced decreasing trend in dust AOD in accordance with MODIS. However, much more analysis and longer dataset are required for establishing this evidence.

Civilising the Savage: Myth, History and Persianisation in the Early Delhi Courts of South Asia

Islamisation ◽  
2017 ◽  
pp. 393-416
Author(s):  
Blain Auer
Keyword(s):  
South Asia ◽  
Twelfth Century ◽  
The South ◽  
Northern India ◽  
Persian Language ◽  
Courtly Culture ◽  
First Time

This chapter explores the success of the Persian language and Persianate courtly culture in South Asia during the important two centuries 1200–1400 in the early Delhi courts. It was at the very end of the twelfth century, in 1192, that Qutb al-Din Aybeg (r. 1206–10), a commander of the Islamic Ghurid empire that originated from northern Afghanistan, captured Delhi, an important city within the realm of the Chauhan kings. Following the death of his Ghurid sultan, Muʿizz al-Din Muhammad b. Sam (r. 1173–1206), the former realms of the Ghurid empire centred in Ghazna were divided up and Qutb al-Din Aybeg took control of Delhi and Lahore, which had served as a southern capital of the Ghaznavid kingdom at the heart of the Punjab region. His successor, Shams al-Din Iltutmish (r. 1211–36), established the Shamsi dynasty, choosing Delhi as his capital. It was the first time in history that an Islamic kingdom with an enduring presence was firmly established in northern India with access throughout the Ganga-Yamuna region, as well as to the south in the Deccan

scholarly journals Investigate Wildfire Impacts on Ozone Production by Vertical Observations and Photochemical Modeling

2020 ◽  
Vol 237 ◽  
pp. 03014
Author(s):  
Bo Wang ◽  
Michael Newchurch ◽  
Shi Kuang ◽  
Arastoo Biazar
Keyword(s):  
Boundary Layer ◽  
Biomass Burning ◽  
Surface Ozone ◽  
Ozone Production ◽  
Ozone Precursors ◽  
Photochemical Modeling ◽  
Enhanced Surface ◽  
Troposphere Ozone ◽  
Effective Integration ◽  
Aerosol Plume

In troposphere, ozone is a toxic secondary pollutant produced when its precursors react in sunlight. An important source of ozone precursors is biomass burning. Here we investigate the impacts of 2016 Southeast U.S. Wildfires on ozone production by integrating vertical resolved ozone profiles and photochemical modeling. The results show that wildfires contributed to ozone lamina at the top of boundary layer and enhanced surface ozone up to about 10ppbv in Southeast U.S.. Ozone lidar observed a lower ozone change with respect to a fast growth of aerosol plume, of which the reason is also investigated. Current results indicate an effective integration of vertical observations and modeling for us to understand the ozone production from fires in troposphere.

New and noteworthy lichen-forming and lichenicolous fungi 10

2020 ◽  
Vol 62 (1-2) ◽  
pp. 69-108
Author(s):  
S. Y. Kondratyuk ◽  
D. K. Upreti ◽  
G. K. Mishra ◽  
S. Nayaka ◽  
K. K. Ingle ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
South Korea ◽  
Eastern Europe ◽  
South Asia ◽  
New Combinations ◽  
Eastern Asia ◽  
Forest Zone ◽  
Mediterranean Europe ◽  
First Time ◽  
India And China

Eight species, new for science, i.e.: Lobothallia gangwondoana S. Y. Kondr., J.-J. Woo et J.-S. Hur and Phyllopsora dodongensis S. Y. Kondr. et J.-S. Hur from South Korea, Eastern Asia, Ioplaca rinodinoides S. Y. Kondr., K. K. Ingle, D. K. Upreti et S. Nayaka, Letrouitia assamana S. Y. Kondr., G. K. Mishra et D. K. Upreti, and Rusavskia indochinensis S. Y. Kondr., D. K. Upreti et S. Nayaka from India and China, South Asia, Caloplaca orloviana S. Y. Kondr. and Rusavskia drevlyanica S. Y. Kondr. et O. O. Orlov from Ukraine, Eastern Europe, as well as Xanthoria ibizaensis S. Y. Kondr. et A. S. Kondr. from Ibiza Island, Spain, Mediterranean Europe, are described, illustrated and compared with closely related taxa. Fominiella tenerifensis S. Y. Kondr., Kärnefelt, A. Thell et Feuerer is for the first time recorded from Mediterranean Europe, Huriella loekoesiana S. Y. Kondr. et Upreti is provided from Russia for the first time, and H. pohangensis S. Y. Kondr., L. Lőkös et J.-S. Hur for the first time from China, Phoma candelariellae Z. Kocakaya et Halıcı is new to Ukraine, and Staurothele frustulenta Vain. is recorded from the Forest Zone of Ukraine for the first time. Twelve new combinations, i.e.: Bryostigma apotheciorum (for Sphaeria apotheciorum A. Massal.), Bryostigma biatoricola (for Arthonia biatoricola Ihlen et Owe-Larss.), Bryostigma dokdoense (for Arthonia dokdoensis S. Y. Kondr., L. Lőkös, B. G. Lee, J.-J. Woo et J.-S. Hur), Bryostigma epiphyscium (for Arthonia epiphyscia Nyl.), Bryostigma lobariellae (for Arthonia lobariellae Etayo), Bryostigma lapidicola (for Lecidea lapidicola Taylor), Bryostigma molendoi (for Tichothecium molendoi Heufl. ex Arnold), Bryostigma neglectulum (for Arthonia neglectula Nyl.), Bryostigma parietinarium (for Arthonia parietinaria Hafellner et Fleischhacker), Bryostigma peltigerinum (for Arthonia vagans var. peltigerina Almq.), Bryostigma phaeophysciae (for Arthonia phaeophysciae Grube et Matzer), Bryostigma stereocaulinum (for Arthonia nephromiaria var. stereocaulina Ohlert), are proposed based on results of combined phylogenetic analysis based on mtSSU and RPB2 gene sequences. Thirty-one new combinations for members of the genus Polyozosia (i.e.: Polyozosia actophila (for Lecanora actophila Wedd.), Polyozosia agardhiana (for Lecanora agardhiana Ach.), Polyozosia altunica (for Myriolecis altunica R. Mamut et A. Abbas), Polyozosia antiqua (for Lecanora antiqua J. R. Laundon), Polyozosia bandolensis (for Lecanora bandolensis B. de Lesd.), Polyozosia behringii (for Lecanora behringii Nyl.), Polyozosia caesioalutacea (for Lecanora caesioalutacea H. Magn.), Polyozosia carlottiana (for Lecanora carlottiana C. J. Lewis et Śliwa), Polyozosia congesta (for Lecanora congesta Clauzade et Vězda), Polyozosia eurycarpa (for Lecanora eurycarpa Poelt, Leuckert et Cl. Roux), Polyozosia expectans (Lecanora expectans Darb.), Polyozosia flowersiana (Lecanora flowersiana H. Magn.), Polyozosia fugiens (for Lecanora fugiens Nyl.), Polyozosia invadens (for Lecanora invadens H. Magn.), Polyozosia juniperina (for Lecanora juniperina Śliwa), Polyozosia latzelii (for Lecanora latzelii Zahlbr.), Polyozosia liguriensis (for Lecanora liguriensis B. de Lesd.), Polyozosia massei (for Myriolecis massei M. Bertrand et J.-Y. Monnat), Polyozosia mons-nivis (for Lecanora mons-nivis Darb.), Polyozosia oyensis (for Lecanora oyensis M.-P. Bertrand et Cl. Roux), Polyozosia percrenata (for Lecanora percrenata H. Magn.), Polyozosia persimilis (for Lecanora hagenii subsp. persimilis Th. Fr.), Polyozosia poeltiana (for Lecanora poeltiana Clauzade et Cl. Roux), Polyozosia prominens (for Lecanora prominens Clauzade et Vězda), Polyozosia prophetae-eliae (for Lecanora prophetae-eliae Sipman), Polyozosia salina (for Lecanora salina H. Magn.), Polyozosia schofieldii (for Lecanora schofieldii Brodo), Polyozosia sverdrupiana (for Lecanora sverdrupiana Øvstedal), Polyozosia torrida (for Lecanora torrida Vain.), Polyozosia wetmorei (for Lecanora wetmorei Śliwa), Polyozosia zosterae (for Lecanora subfusca? zosterae Ach.)) are proposed.

scholarly journals Modelling the impact of megacities on local, regional and global tropospheric ozone and the deposition of nitrogen species

2013 ◽  
Vol 13 (24) ◽  
pp. 12215-12231 ◽  
Author(s):  
Z. S. Stock ◽  
M. R. Russo ◽  
T. M. Butler ◽  
A. T. Archibald ◽  
M. G. Lawrence ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Climate Model ◽  
Surface Ozone ◽  
Global Scale ◽  
Chemical Environment ◽  
Ozone Production ◽  
The Uk ◽  
The Impact ◽  
Local Emissions

Abstract. We examine the effects of ozone precursor emissions from megacities on present-day air quality using the global chemistry–climate model UM-UKCA (UK Met Office Unified Model coupled to the UK Chemistry and Aerosols model). The sensitivity of megacity and regional ozone to local emissions, both from within the megacity and from surrounding regions, is important for determining air quality across many scales, which in turn is key for reducing human exposure to high levels of pollutants. We use two methods, perturbation and tagging, to quantify the impact of megacity emissions on global ozone. We also completely redistribute the anthropogenic emissions from megacities, to compare changes in local air quality going from centralised, densely populated megacities to decentralised, lower density urban areas. Focus is placed not only on how changes to megacity emissions affect regional and global NOx and O3, but also on changes to NOy deposition and to local chemical environments which are perturbed by the emission changes. The perturbation and tagging methods show broadly similar megacity impacts on total ozone, with the perturbation method underestimating the contribution partially because it perturbs the background chemical environment. The total redistribution of megacity emissions locally shifts the chemical environment towards more NOx-limited conditions in the megacities, which is more conducive to ozone production, and monthly mean surface ozone is found to increase up to 30% in megacities, depending on latitude and season. However, the displacement of emissions has little effect on the global annual ozone burden (0.12% change). Globally, megacity emissions are shown to contribute ~3% of total NOy deposition. The changes in O3, NOx and NOy deposition described here are useful for quantifying megacity impacts and for understanding the sensitivity of megacity regions to local emissions. The small global effects of the 100% redistribution carried out in this study suggest that the distribution of emissions on the local scale is unlikely to have large implications for chemistry–climate processes on the global scale.

30 years of surface ozone measurements in Austria: long-term trends, attainment statistics, and changes in the temperature sensitivity of surface ozone production

2021 ◽  
Author(s):  
Christoph Stähle ◽  
Monika Mayer ◽  
Christian Schmidt ◽  
Jessica Kult ◽  
Vinzent Klaus ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Surface Ozone ◽  
Global Radiation ◽  
Mixing Layer ◽  
Ozone Production ◽  
Daily Minimum Temperature ◽  
Monitoring Networks ◽  
Seasonal Basis ◽  
Minimum Daily Temperature ◽  
The Impact

<p>As the production of ozone in surface air is determined by ambient temperature and by the prevalent chemical regime, a very different temperature dependence of ozone production emerges for nitrogen oxides (NO<sub>x</sub>) and volatile organic compounds (VOC) limited regions. In this study we evaluated the temperature sensitivity of ozone production for rural, suburban as well as urban sites in Austria on seasonal basis. The analysis is based on 30 years of observational data from Austrian monitoring networks for the time period 1990 – 2019. Reductions in precursor emissions as observed in 2020 in Austria due to the pandemic will be used to test the obtained results. Surface ozone, NO<sub>x</sub>, daily sums of global radiation and minimum daily temperature are used as covariates in our study. The observed NO<sub>x</sub> to VOC ratio at individual sites is variable over time due to changes in precursor emissions and/or the variability of meteorological parameters such as mixing layer height. At the site level we relate the temperature sensitivity of ozone production to the daily mean NO<sub>x</sub> mixing ratio and the daily minimum temperature. This information allows us to determine the impact of past/future temperature changes on surface ozone abundance in the context of reductions of NO<sub>x</sub> emissions and changing methane backgrounds.</p>

scholarly journals Variations in O<sub>3</sub>, CO, and CH<sub>4</sub> over the Bay of Bengal during the summer monsoon season: Ship-borne measurements and model simulations

2016 ◽  
Author(s):  
Imran A. Girach ◽  
Narendra Ojha ◽  
Prabha R. Nair ◽  
Andrea Pozzer ◽  
Yogesh K. Tiwari ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Bay Of Bengal ◽  
Monsoon Season ◽  
Surface Ozone ◽  
Ozone Production ◽  
Spatial And Temporal Variability ◽  
Summer Monsoon Season ◽  
Rainfall Events ◽  
Model Simulations ◽  
Mixing Ratios

Abstract. We present ship-borne measurements of surface ozone, carbon monoxide and methane over the Bay of Bengal (BoB), the first time such measurements have been taken during the summer monsoon season, as a part of the Continental Tropical Convergence Zone (CTCZ) experiment during 2009. O3, CO, and CH4 mixing ratios exhibited significant spatial and temporal variability in the ranges of 8–54 nmol mol−1, 50–200 nmol mol−1, and 1.57–2.15 µmol mol−1, with means of 29.7 ± 6.8 nmol mol−1, 96 ± 25 nmol mol−1, and 1.83 ± 0.14 µmol mol−1, respectively. The average mixing ratios of trace gases over northern BoB (O3: 30 ± 7 nmol mol−1, CO: 95 ± 25 nmol mol−1, CH4: 1.86 ± 0.12 µmol mol−1), in airmasses from northern or central India, did not differ much from those over central BoB (O3: 27 ± 5 nmol mol−1, CO: 101 ± 27 nmol mol−1, CH4: 1.72 ± 0.14 µmol mol−1), in airmasses from southern India. Spatial variability is observed to be most significant for CH4. The ship-based observations, in conjunction with backward air trajectories and ground-based measurements over the Indian region, are analyzed to estimate a net ozone production of 1.5–4 nmol mol−1 day−1 in the outflow. Ozone mixing ratios over the BoB showed large reductions (by ~ 20 nmol mol−1) during four rainfall events. Temporal changes in the meteorological parameters, in conjunction with ozone vertical profiles, indicate that these low ozone events are associated with downdrafts of free-tropospheric ozone-poor airmasses. While the observed variations in O3 and CO are successfully reproduced using the Weather Research and Forecasting model with Chemistry (WRF-Chem), this model overestimates mean concentrations by about 20 %, generally overestimating O3 mixing ratios during the rainfall events. Analysis of the chemical tendencies from model simulations for a low-O3 event on August 10, 2009, captured successfully by the model, shows the key role of horizontal advection in rapidly transporting ozone-rich airmasses across the BoB. Our study fills a gap in the availability of trace gas measurements over the BoB, and when combined with data from previous campaigns, reveals large seasonal amplitude (~ 39 and ~ 207 nmol mol−1 for O3 and CO, respectively) over the northern BoB.

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