Transport of aerosols into the UTLS and their impact on the Asian monsoon region as seen in a global model simulation

Fadnavis, Suvarna; Semeniuk, K.; Pozzoli, Luca; Schultz, Martin; Ghude, Sachin D.; Das, Subrata Kumar; Kakatkar, Rashmi

doi:10.5194/acp-13-8771-2013

Cited by 108 publications

(172 citation statements)

References 69 publications

(104 reference statements)

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“…It includes O x -NO xhydrocarbons with 63 tracers and 168 reactions. The details of the parameterizations and emissions used in the model as well as a validation of the results are described by Fadnavis et al (2013Fadnavis et al ( , 2014Fadnavis et al ( , 2015 and Pozzoli et al (2011).…”

Section: Model Set-upmentioning

confidence: 99%

“…These anomalies portray the effect of Asian boundary layer emissions (NMVOCs and NO x ) on the upper level anticyclone and the associated eddies. A number of studies (Randel et al, 2010;Fadnavis et al, 2013Fadnavis et al, , 2015Vogel et al, 2014) Further, we analyse the vertical distribution of anomalies of PAN and ozone. Figure 8e-h show longitude-pressure sections of anomalies of PAN.…”

Section: Influence Of Asian Emissions On Extratropical Utlsmentioning

confidence: 99%

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Transport of trace gases via eddy shedding from the Asian summer monsoon anticyclone and associated impacts on ozone heating rates

et al. 2018

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Abstract. The highly vibrant Asian summer monsoon (ASM) anticyclone plays an important role in efficient transport of Asian tropospheric air masses to the extratropical upper troposphere and lower stratosphere (UTLS). In this paper, we demonstrate long-range transport of Asian trace gases via eddy-shedding events using MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) satellite observations, ERA-Interim reanalysis data and the ECHAM5-HAMMOZ global chemistry-climate model. Model simulations and observations consistently show that Asian boundary layer trace gases are lifted to UTLS altitudes in the monsoon anticyclone and are further transported horizontally eastward and westward by eddies detached from the anticyclone. We present an event of eddy shedding during 1-8 July 2003 and discuss a 1995-2016 climatology of eddy-shedding events. Our analysis indicates that eddies detached from the anticyclone contribute to the transport of Asian trace gases away from the Asian region to the western Pacific (20-30 • N, 120-150 • E) and western Africa (20-30 • N, 0-30 • E). Over the last two decades, the estimated frequency of occurrence of eddy-shedding events is ∼ 68 % towards western Africa and ∼ 25 % towards the western Pacific.Model sensitivity experiments considering a 10 % reduction in Asian emissions of non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NO x ) were performed with ECHAM5-HAMMOZ to understand the impact of Asian emissions on the UTLS. The model simulations show that transport of Asian emissions due to eddy shedding significantly affects the chemical composition of the upper troposphere (∼ 100-400 hPa) and lower stratosphere (∼ 100-80 hPa) over western Africa and the western Pacific. The 10 % reduction of NMVOCs and NO x Asian emissions leads to decreases in peroxyacetyl nitrate (PAN) (2 %-10 % near 200-80 hPa), ozone (1 %-4.5 % near ∼ 150 hPa) and ozone heating rates (0.001-0.004 K day −1 near 300-150 hPa) in the upper troposphere over western Africa and the western Pacific.

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Section: Model Set-upmentioning

confidence: 99%

Section: Influence Of Asian Emissions On Extratropical Utlsmentioning

confidence: 99%

Transport of trace gases via eddy shedding from the Asian summer monsoon anticyclone and associated impacts on ozone heating rates

et al. 2018

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“…The elevated concentrations of aerosols in the anti-cyclone have also been shown to weaken circulation patterns and reduce total monsoon precipitation over southern India (Ramanathan et al, 2005;Fadnavis et al, 2013) while intensifying the monsoon over the foothills of the Himalaya (Lau et al, 2006). In addition to warming the atmosphere, the rising concentrations of BC and O 3 over southern Asia (e.g., Ramanathan and Carmichael, 2008) have detrimental impacts on human health.…”

Section: Introductionmentioning

confidence: 99%

Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

Dhungel

Kathayat²,

Mahata

et al. 2018

Atmos. Chem. Phys.

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Abstract. Anthropogenic emissions from the combustion of fossil fuels and biomass in Asia have increased in recent years. High concentrations of reactive trace gases and lightabsorbing and light-scattering particles from these sources form persistent haze layers, also known as atmospheric brown clouds, over the Indo-Gangetic plains (IGP) from December through early June. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, observational evidence of the transport of polluted air masses through Himalayan valleys has been lacking to date. To evaluate this pathway, we measured black carbon (BC), ozone (O 3 ), and associated meteorological conditions within the Kali Gandaki Valley (KGV), Nepal, from January 2013 to July 2015. BC and O 3 varied over both diurnal and seasonal cycles. Relative to nighttime, mean BC and O 3 concentrations within the valley were higher during daytime when the up-valley flow (average velocity of 17 m s −1 ) dominated. BC and O 3 concentrations also varied seasonally with minima during the monsoon season (July to September). Concentrations of both species subsequently increased post-monsoon and peaked during March to May. Average concentrations for O 3 during the seasonally representative months of April, August, and November were 41.7, 24.5, and 29.4 ppbv, respectively, while the corresponding BC concentrations were 1.17, 0.24, and 1.01 µg m −3 , respectively. Up-valley fluxes of BC were significantly greater than down-valley fluxes during all seasons. In addition, frequent episodes of BC concentrations 2-3 times higher than average persisted from several days to a week during non-monsoon months. Our observations of increases in BC concentration and fluxes in the valley, particularly during pre-monsoon, provide evidence that trans-Himalayan valleys are important conduits for transport of pollutants from the IGP to the higher Himalaya.

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“…The estimated growth of BC is 46 % (33 % in OC) over China and 41 % (35 % in OC) over India during 2000 to 2010 (Lu et al, 2011). On a regional scale, their emissions are high over the densely populated Indo-Gangetic Plain in India and in eastern China Lelieveld, 2001;Gautam et al, 2011;Fadnavis et al, 2013;Zhang et al, 2015). Over the Asian region (here specifically the Indo-Gangetic Plain and northeastern China) emission of OC is almost twice that of BC (Fig.…”

Section: Introductionmentioning

confidence: 93%

“…Satellite observations reveal transport of trace gases (CO, PAN, H 2 O, HCN) into the upper-level monsoon anticyclone by deep monsoon convection (Park et al, 2009;Randel et al, 2010;Kunze et al, 2010;Ploeger et al, 2011Ploeger et al, , 2012Ploeger et al, , 2013Fadnavis et al, 2014Fadnavis et al, , 2015Govardhan et al, 2017). Moreover, both back trajectory analysis based on CALIOP observations (Vernier et al, 2015) and modeling studies (Fadnavis et al, 2013) indicate that deep monsoon convection transports boundary layer aerosols into the upper troposphere and lower stratosphere (UTLS). Measurements from the Civil Aircraft for Regular Investigation of atmosphere Based on an Instrument Container (CARIBIC) campaign show aerosols at the lower levels in the ATAL contain higher levels of carbonaceous and sulfate aerosols.…”

Section: Introductionmentioning

confidence: 99%

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

et al. 2017

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Abstract. Recent satellite observations show efficient vertical transport of Asian pollutants from the surface to the upper-level anticyclone by deep monsoon convection. In this paper, we examine the transport of carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), into the monsoon anticyclone using of ECHAM6-HAM, a global aerosol climate model. Further, we investigate impacts of enhanced (doubled) carbonaceous aerosol emissions on the upper troposphere and lower stratosphere (UTLS), underneath monsoon circulation and precipitation from sensitivity simulations.The model simulation shows that boundary layer aerosols are transported into the monsoon anticyclone by the strong monsoon convection from the Bay of Bengal, southern slopes of the Himalayas and the South China Sea. Doubling of emissions of both BC and OC aerosols over Southeast Asia (10 • S-50 • N, 65-155 • E) shows that lofted aerosols produce significant warming (0.6-1 K) over the Tibetan Plateau (TP) near 400-200 hPa and instability in the middle/upper troposphere. These aerosols enhance radiative heating rates (0.02-0.03 K day −1 ) near the tropopause. The enhanced carbonaceous aerosols alter aerosol radiative forcing (RF) at the surface by −4.74 ± 1.42 W m −2 , at the top of the atmosphere (TOA) by +0.37 ± 0.26 W m −2 and in the atmosphere by +5.11 ± 0.83 W m −2 over the TP and Indo-Gangetic Plain region • N, 80-110 • E). Atmospheric warming increases vertical velocities and thereby cloud ice in the upper troposphere. Aerosol induced anomalous warming over the TP facilitates the relative strengthening of the monsoon Hadley circulation and increases moisture inflow by strengthening the cross-equatorial monsoon jet. This increases precipitation amounts over India (1-4 mm day −1 ) and eastern China (0.2-2 mm day −1 ). These results are significant at the 99 % confidence level.

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Transport of aerosols into the UTLS and their impact on the Asian monsoon region as seen in a global model simulation

Cited by 108 publications

References 69 publications

Transport of trace gases via eddy shedding from the Asian summer monsoon anticyclone and associated impacts on ozone heating rates

Transport of trace gases via eddy shedding from the Asian summer monsoon anticyclone and associated impacts on ozone heating rates

Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

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