Acetone in the upper troposphere and lower stratosphere: Impact on trace gases and aerosols

Abstract. To investigate the seasonal characteristics of trace gas distributions in the extratropical upper troposphere and lower stratosphere (ExUTLS) as well as stratosphere–troposphere exchange processes, origin fractions of air masses originating in the stratosphere, tropical troposphere, midlatitude lower troposphere (LT), and high-latitude LT in the ExUTLS are estimated using 10-year backward trajectories calculated with European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim data as the meteorological input. Time series of trace gases obtained from ground-based and airborne observations are incorporated into the trajectories, thus reconstructing spatiotemporal distributions of trace gases in the ExUTLS. The reconstructed tracer distributions are analyzed with the origin fractions and the stratospheric age of air (AoA) estimated using the backward trajectories. The reconstructed distributions of SF6 and CO2 in the ExUTLS are linearly correlated with those of AoA because of their chemically passive behavior and quasi-stable increasing trends in the troposphere. Distributions of CH4, N2O, and CO are controlled primarily by chemical decay along the transport path from the source region via the stratosphere and subsequent mixing of such stratospheric air masses with tropospheric air masses in the ExUTLS.

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Seasonality of the MJO Impact on Upper Troposphere–Lower Stratosphere Temperature, Circulation, and Composition

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-19-0183.1 ◽

2020 ◽

Vol 77 (4) ◽

pp. 1455-1473 ◽

Cited By ~ 1

Author(s):

Olga V. Tweedy ◽

Luke D. Oman ◽

Darryn W. Waugh

Keyword(s):

Carbon Monoxide ◽

Water Vapor ◽

Wave Front ◽

Lower Stratosphere ◽

Trace Gases ◽

Low Pressure ◽

Kelvin Wave ◽

Seasonal Differences ◽

Upper Troposphere ◽

Circulation Anomalies

Abstract Seasonal differences in the impact of the Madden–Julian oscillation (MJO) on tropical and extratropical upper troposphere–lower stratosphere (UTLS) temperature, circulation, and trace gases are examined using trace gases (ozone, carbon monoxide, and water vapor) and temperature from measurements from the Microwave Limb Sounder (MLS) and meteorological fields from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). During boreal winter months (November–February), atmospheric fields exhibit a well-known planetary-scale perturbation consistent with the upper-level flow modeled by Gill, with twin high and low pressure extratropical systems associated with a Rossby wave response. However, the circulation anomalies in the UTLS differ during boreal summer months (June–September), when background UTLS circulation north of the equator is dominated by the Asian summer monsoon anticyclone. The twin high and low pressure extratropical systems are much weaker but with a stronger equatorial Kelvin wave front that encircles the globe as the MJO propagates eastward. These differences are explained in terms of seasonal variations in vertically propagating Kelvin waves that strongly depend on the zonal structure of the climatological background winds. The trace gas response to the MJO is strongly coherent with circulation anomalies showing strong seasonal differences. The stronger equatorial Kelvin wave front during the summer produces enhanced upwelling in the tropical tropopause layer, resulting in significant cooling of this region, reduced ozone and water vapor, and enhanced carbon monoxide.

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Deep-convective influence on the upper troposphere–lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign results

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-12193-2020 ◽

2020 ◽

Vol 20 (20) ◽

pp. 12193-12210

Author(s):

Silvia Bucci ◽

Bernard Legras ◽

Pasquale Sellitto ◽

Francesco D'Amato ◽

Silvia Viciani ◽

...

Keyword(s):

Asian Monsoon ◽

Lower Stratosphere ◽

Trace Gases ◽

Vertical Motion ◽

Back Trajectory ◽

Convective System ◽

Small Contribution ◽

Back Trajectories ◽

Air Masses ◽

Upper Troposphere

Abstract. The StratoClim stratospheric aircraft campaign took place in summer 2017 in Nepal (27 July–10 August) and provided for the first time a wide dataset of observations of air composition inside the Asian monsoon anticyclone (AMA). In the framework of this project, with the purpose of modelling the injection of pollutants and natural compounds into the stratosphere, we performed a series of diffusive back trajectory runs along the flights' tracks. The availability of in situ measurements of trace gases has been exploited to evaluate the capability of the trajectory system to reproduce the transport in the upper troposphere–lower stratosphere (UTLS) region. The diagnostics of the convective sources and mixing in the air parcel samples have been derived by integrating the trajectory output with high-resolution observations of cloud tops from the Meteosat Second Generation (MSG1) and Himawari geostationary satellites. Back trajectories have been calculated using meteorological fields from European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-Interim and ERA5) at 3 and 1 h resolution, using both kinematic and diabatic vertical motion. The comparison among the different trajectory runs shows, in general, a higher consistency with observed data as well as a better agreement between the diabatic and kinematic version when using ERA5-based runs with respect to ERA-Interim. Overall, a better capacity in reproducing the pollution features is finally found in the diabatic version of the ERA5 runs. We therefore adopt this setting to analyse the convective influence in the UTLS starting from the StratoClim observations. A large variety of transport conditions have been individuated during the eight flights of the campaign. The larger influence by convective injections is found from the continental sources of China and India. Only a small contribution appears to be originated from maritime regions, in particular the South Pacific and the Bay of Bengal, which, unexpectedly, was not particularly active during the period of the campaign. In addition, a mass of clean air injected from a typhoon has also been detected at around 18 km. Thin filamentary structures of polluted air, characterized by peaks in CO, are observed, mostly associated with young convective air (age less than a few days) and with a predominant South China origin. The analysis revealed a case of direct injection of highly polluted air close to the level of the tropopause (anomalies of around 80 ppbv injected at 16 km) that then kept rising inside the anticyclonic circulation. Due to the location of the campaign, air from continental India, in contrast, has been only observed to be linked to air masses that recirculated within the anticyclone for 10 to 20 d, resulting in a lower concentration of the trace gas. The analysis of a flight overpassing an intense convective system close to the southern Nepalese border revealed the injection of very young air (few hours of age) directly in the tropopause region (∼18 km), visible in the trace gases as an enhancement in CO and a depletion in the O3 one. From the whole campaign, a vertical stratification in the age of air is observed: up to 15 km, the age is less than 3 d, and these fresh air masses constitute almost the totality of the air composition. A transition layer is then individuated between 15 and 17 km, where the convective contribution is still dominant, and the ages vary between 1 and 2 weeks. Above this level, the mean age of the air sampled by the aircraft is estimated to be 20 d. There, the convective contribution rapidly decreases with height and finally becomes negligible around 20 km.

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The governing processes and timescales of stratosphere-to-troposphere transport and its contribution to ozone in the Arctic troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-3011-2009 ◽

2009 ◽

Vol 9 (9) ◽

pp. 3011-3025 ◽

Cited By ~ 33

Author(s):

Q. Liang ◽

A. R. Douglass ◽

B. N. Duncan ◽

R. S. Stolarski ◽

J. C. Witte

Keyword(s):

Lower Stratosphere ◽

Trace Gases ◽

Lower Troposphere ◽

Threshold Level ◽

The Arctic ◽

Trace Gas ◽

Seasonal Cycles ◽

Upper Troposphere ◽

Budget Analysis ◽

Wet Removal

Abstract. We used the seasonality of a combination of atmospheric trace gases and idealized tracers to examine stratosphere-to-troposphere transport and its influence on tropospheric composition in the Arctic. Maximum stratosphere-to-troposphere transport of CFCs and O3 occurs in April as driven by the Brewer-Dobson circulation. Stratosphere-troposphere exchange (STE) occurs predominantly between 40° N to 80° N with stratospheric influx in the mid-latitudes (30–70° N) accounting for 67–81% of the air of stratospheric origin in the Northern Hemisphere extratropical troposphere. Transport from the lower stratosphere to the lower troposphere (LT) takes three months on average, one month to cross the tropopause, the second month to travel from the upper troposphere (UT) to the middle troposphere (MT), and the third month to reach the LT. During downward transport, the seasonality of a trace gas can be greatly impacted by wet removal and chemistry. A comparison of idealized tracers with varying lifetimes suggests that when initialized with the same concentrations and seasonal cycles at the tropopause, trace gases that have shorter lifetimes display lower concentrations, smaller amplitudes, and earlier seasonal maxima during transport to the LT. STE contributes to O3 in the Arctic troposphere directly from the transport of O3 and indirectly from the transport of NOy. Direct transport of O3 from the stratosphere accounts for 78% of O3 in the Arctic UT with maximum contributions occurring from March to May. The stratospheric contribution decreases significantly in the MT/LT (20–25% of total O3) and shows a very weak March–April maximum. Our NOx budget analysis in the Arctic UT shows that during spring and summer, the stratospheric injection of NOy-rich air increases NOx concentrations above the 20 pptv threshold level, thereby shifting the Arctic UT from a regime of net photochemical ozone loss to one of net production with rates as high as +16 ppbv/month.

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The Convective Transport of Active Species in the Tropics (CONTRAST) Experiment

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-14-00272.1 ◽

2017 ◽

Vol 98 (1) ◽

pp. 106-128 ◽

Cited By ~ 32

Author(s):

L. L. Pan ◽

E. L. Atlas ◽

R. J. Salawitch ◽

S. B. Honomichl ◽

J. F. Bresch ◽

...

Keyword(s):

Lower Stratosphere ◽

Limit Of Detection ◽

Trace Gases ◽

Regional Distribution ◽

Active Species ◽

Convective Transport ◽

In Situ Measurements ◽

Upper Troposphere ◽

The Tropics

Abstract The Convective Transport of Active Species in the Tropics (CONTRAST) experiment was conducted from Guam (13.5°N, 144.8°E) during January–February 2014. Using the NSF/NCAR Gulfstream V research aircraft, the experiment investigated the photochemical environment over the tropical western Pacific (TWP) warm pool, a region of massive deep convection and the major pathway for air to enter the stratosphere during Northern Hemisphere (NH) winter. The new observations provide a wealth of information for quantifying the influence of convection on the vertical distributions of active species. The airborne in situ measurements up to 15-km altitude fill a significant gap by characterizing the abundance and altitude variation of a wide suite of trace gases. These measurements, together with observations of dynamical and microphysical parameters, provide significant new data for constraining and evaluating global chemistry–climate models. Measurements include precursor and product gas species of reactive halogen compounds that impact ozone in the upper troposphere/lower stratosphere. High-accuracy, in situ measurements of ozone obtained during CONTRAST quantify ozone concentration profiles in the upper troposphere, where previous observations from balloonborne ozonesondes were often near or below the limit of detection. CONTRAST was one of the three coordinated experiments to observe the TWP during January–February 2014. Together, CONTRAST, Airborne Tropical Tropopause Experiment (ATTREX), and Coordinated Airborne Studies in the Tropics (CAST), using complementary capabilities of the three aircraft platforms as well as ground-based instrumentation, provide a comprehensive quantification of the regional distribution and vertical structure of natural and pollutant trace gases in the TWP during NH winter, from the oceanic boundary to the lower stratosphere.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-11493-2018 ◽

2018 ◽

Vol 18 (15) ◽

pp. 11493-11506 ◽

Cited By ~ 9

Author(s):

Suvarna Fadnavis ◽

Chaitri Roy ◽

Rajib Chattopadhyay ◽

Christopher E. Sioris ◽

Alexandru Rap ◽

...

Keyword(s):

Lower Stratosphere ◽

Asian Summer Monsoon ◽

Trace Gases ◽

Western Pacific ◽

Heating Rates ◽

Upper Troposphere ◽

Western Africa ◽

Asian Summer ◽

The Western Pacific ◽

Eddy Shedding

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 (NOx) 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 NOx 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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The seasonal and zonal differences in the temperature, circulation and composition of the tropical upper troposphere and lower stratosphere due to the MJO

10.5194/egusphere-egu2020-10418 ◽

2020 ◽

Author(s):

Olga Tweedy ◽

Luke Oman ◽

Darryn Waugh

Keyword(s):

Lower Stratosphere ◽

Trace Gases ◽

Trace Gas ◽

Boreal Summer ◽

Boreal Winter ◽

Kelvin Wave ◽

Upper Troposphere ◽

Circulation Anomalies ◽

Gas Response ◽

Tropical Upper Troposphere

<p>The intraseasonal (20-90 day) variability of the tropical upper troposphere/lower stratosphere (UTLS)&#160; is dominated by the Madden-Julian Oscillation (MJO). Previous studies showed a strong connection between the MJO and variability in the UTLS circulation and trace gases. However, seasonality of UTLS circulation and trace gas response to the MJO has received very little attention in the literature. In this study, we use observations of trace gases (ozone, carbon monoxide and water vapor) and temperature from the Microwave Limb Sounder (MLS, version 4) and meteorological fields from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalyses to examine and explain the seasonal and zonal differences in the UTLS temperature, circulation, and trace gas anomalies associated with the MJO propagation. We find that the response of the UTLS during boreal summer months (June -September, JJAS) is different from the response during boreal winter months (November -February, NDJF). Ozone, temperature and circulation anomalies during JJAS are more zonally symmetric with a stronger Kelvin wave response than during NDJF. These differences are explained in terms of seasonal variations in vertically propagating Kelvin waves that strongly depend on the zonal structure of the climatological zonal winds. The trace gas response to the MJO is in agreement with circulation anomalies, showing strong seasonal differences. The analysis of MLS observations presented in this study may be useful for evaluation and validation of the MJO-related physical and dynamical processes in a hierarchy of models.</p>

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Large Anomalies in the Tropical Upper Troposphere Lower Stratosphere (UTLS) Trace Gases Observed during the Extreme 2015–16 El Niño Event by Using Satellite Measurements

Remote Sensing ◽

10.3390/rs11060687 ◽

2019 ◽

Vol 11 (6) ◽

pp. 687 ◽

Cited By ~ 7

Author(s):

S. Ravindrababu ◽

M. Ratnam ◽

Ghouse Basha ◽

Yuei-An Liou ◽

N. Reddy

Keyword(s):

21St Century ◽

El Niño ◽

Lower Stratosphere ◽

El Nino ◽

Trace Gases ◽

Equatorial Region ◽

Upper Troposphere ◽

El Niño Event ◽

Cold Point ◽

Tropical Upper Troposphere

It is well reported that the 2015–16 El Niño event is one of the most intense and long lasting events in the 21st century. The quantified changes in the trace gases (Ozone (O3), Carbon Monoxide (CO) and Water Vapour (WV)) in the tropical upper troposphere and lower stratosphere (UTLS) region are delineated using Aura Microwave Limb Sounder (MLS) and Atmosphere Infrared Radio Sounder (AIRS) satellite observations from June to December 2015. Prior to reaching its peak intensity of El Niño 2015–16, large anomalies in the trace gases (O3 and CO) were detected in the tropical UTLS region, which is a record high in the 21st century. A strong decrease in the UTLS (at 100 and 82 hPa) ozone (~200 ppbv) in July-August 2015 was noticed over the entire equatorial region followed by large enhancement in the CO (150 ppbv) from September to November 2015. The enhancement in the CO is more prevalent over the South East Asia (SEA) and Western Pacific (WP) regions where large anomalies of WV in the lower stratosphere are observed in December 2015. Dominant positive cold point tropopause temperature (CPT-T) anomalies (~5 K) are also noticed over the SEA and WP regions from the high-resolution Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Global Position System (GPS) Radio Occultation (RO) temperature profiles. These observed anomalies are explained in the light of dynamics and circulation changes during El Niño.

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VARIASI TRACE GASES SELAMA 10 TAHUN DAN PENCAMPURAN DI SEKITAR LAPISAN TROPOPAUSE DI INDONESIA BERBASIS SATELIT (TRACE GASES VARIATION FOR 10 YEARS AND MIXING AROUND THE TROPOPAUSE LAYERS IN INDONESIA BASED ON SATELLITE)

Jurnal Sains Dirgantara ◽

10.30536/j.jsd.2017.v14.a2523 ◽

2018 ◽

Vol 14 (2) ◽

pp. 83

Author(s):

Novita Ambarsari ◽

Ninong Komala ◽

Fanny Aditya Putri

Keyword(s):

Time Series ◽

Cross Section ◽

Lower Stratosphere ◽

Trace Gases ◽

Radiation Budget ◽

Vertical Profiles ◽

Upper Troposphere ◽

Tropical Tropopause Layer ◽

Tropical Tropopause ◽

Budget Analysis

Measurement of trace gases (CO, O3, CH3Cl, HCl, H2O, and HNO3) and temperatures around upper troposphere/lower stratosphere (UT/LS) or rather around Tropical Tropopause Layer (TTL) in Indonesia by using Microwave Limb Sounder (MLS) instrument board on Satellite AURA for 2005-2014 period to make variations of these gases over the 10 years around TTL allows to be studied more deeply. TTL becomes the main route entry of chemical compounds and aerosols originating in the troposphere into the stratosphere. The composition of minor gases in the TTL is very important because it affects the global radiation budget. Analysis of vertical profiles of these gases in the TTL was done to determine the suitability of the concept of TTL which starts from the upper troposphere to the lower stratosphere. Other method are the time series diagram of the altitude (height versus time series cross section) which shows the annual and interannual variations in vertical profiles of these gases in the TTL and the possible influence of the dynamics of the atmosphere. The results showed correlation of these gases with ozone showed most of the air in the stratosphere is experiencing mixing in the TTL. In addition, changes in concentration and temperature values in the TTL have been calculated using the trends of each parameter and it is known that the parameters of HCl, CH3Cl, and temperature show respective decreases of -0.036 ppmv, -0.024 ppmv, and -0.456 K. As for other parameters such as ozone, CO, H2O, and HNO3 showed an increase of respectively 0.0036 ppmv, 0.0096 ppmv, 0.108 ppmv, and 0.06 ppmv. AbstrakPengukuran trace gases (CO, O3, CH3Cl, HCl, H2O, HNO3) dan temperatur di sekitar lapisan troposfer atas/stratosfer bawah (UT/LS) atau tepatnya di sekitar Tropical Tropopause Layer (TTL) di Indonesia menggunakan instrumen Microwave Limb Sounder (MLS) pada Satelit AURA periode 2005-2014 menjadikan variasi gas-gas tersebut selama 10 tahun di sekitar TTL memungkinkan untuk dikaji lebih dalam. TTL menjadi jalur utama masuknya senyawa-senyawa kimia dan aerosol yang bersumber di troposfer ke stratosfer. Komposisi gas-gas minor di TTL sangat penting karena mempengaruhi budget radiasi global. Analisis profil vertikal gas-gas tersebut di TTL dilakukan untuk mengetahui kesesuaian konsep TTL yang dimulai dari lapisan troposfer atas hingga ke stratosfer bawah. Metode lainnya adalah dengan diagram time series terhadap ketinggian (time series versus height cross section) yang menunjukkan variasi tahunan maupun antar tahunan profil vertikal gas-gas tersebut di TTL serta kemungkinan adanya pengaruh dari proses dinamika atmosfer. Hasil penelitian menunjukkan korelasi gas-gas tersebut dengan ozon menunjukkan adanya sebagian udara di stratosfer yang mengalami pencampuran di wilayah TTL. Selain itu, perubahan nilai konsentrasi dan temperatur di TTL telah dihitung menggunakan trend masing-masing parameter dan diketahui bahwa parameter HCl, CH3Cl, dan temperatur menunjukkan penurunan masing-masing sebesar -0,036 ppmv, -0,024 ppmv, dan -0,456 K. Adapun parameter lain seperti ozon, CO, H2O, dan HNO3 menunjukkan adanya peningkatan masing-masing sebesar 0,0036 ppmv, 0,0096 ppmv, 0,108 ppmv, dan 0,06 ppmv.

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

10.5194/acp-2018-168 ◽

2018 ◽

Author(s):

Suvarna Fadnavis ◽

Chaitri Roy ◽

Rajib Chattopadhyay ◽

Christopher E. Sioris ◽

Alexandru Rap ◽

...

Keyword(s):

West Africa ◽

Lower Stratosphere ◽

Asian Summer Monsoon ◽

Trace Gases ◽

Heating Rates ◽

The West ◽

West Pacific ◽

Upper Troposphere ◽

Asian Summer ◽

Eddy Shedding

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 re-analysis data and the ECHAM5–HAMMOZ global chemistry–climate model. Model simulations and observations consistently show that the 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 are instrumental in distributing the Asian trace gases away from the Asian region to the West-Pacific (20°–30° N; 120°–150° E) and West-Africa (20°–30° N, 0°–30° E). Over the last two decades, the estimated frequency of eddy shedding is ~ 68 % towards West-Africa and ~ 25 % towards the West-Pacific. Model sensitivity experiments for a 10 % reduction in Asian emissions of non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NOx) 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 West-Africa and the West-Pacific. The 10 % reduction of NMVOCs and NOx 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 West-Africa and the West-Pacific.

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