scholarly journals Long-range transport pathways of tropospheric source gases originating in Asia into the northern lower stratosphere during the Asian monsoon season 2012

2016 ◽  
Author(s):  
Bärbel Vogel ◽  
Gebhard Günther ◽  
Rolf Müller ◽  
Jens-Uwe Grooß ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Monsoon Season ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Air Masses ◽  
Horizontal Transport ◽  
Source Regions ◽  
Subtropical Jet

Abstract. Global simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) using artificial tracers of air mass origin are used to analyze transport pathways from the Asian monsoon region into the lower stratosphere. In a case study, the transport of air masses from the Asian monsoon anticyclone originating in India/China by an eastward migrating anticyclone breaking off from the main anticyclone on 20 September 2012 and filaments separated at the northeastern flank of the anticyclone are analyzed. Enhanced contributions of young air masses (younger than 5 months) are found within the separated anticyclone confined at the top by the thermal tropopause. Further, these air masses are confined by the anticyclonic circulation and at the polar side by the subtropical jet such as the vertical structure looks like a bubble within the upper troposphere. Subsequently, these air masses are transported eastwards along the subtropical jet and enter the lower stratosphere by quasi-horizontal transport in a region of double tropopauses most likely associated with Rossby wave breaking events. As a result, thin filaments with enhanced signatures of tropospheric trace gases are measured in the lower stratosphere over Europe during the TACTS/ESMVal campaign in September 2012 in very good agreement with CLaMS simulations. Our simulations demonstrate that source regions in Asia and in the Pacific Ocean have a significant impact on the chemical composition of the lower stratosphere of the Northern Hemisphere by flooding the extratropical lower stratosphere with young moist air masses in particular at end of the monsoon season in September/October 2012 (up to ~30 % at 380 K) in contrast to the southern hemisphere. End of October 2012, approximately 1.5 ppmv H2O is found in the lower northern hemisphere stratosphere (at 380 K) from source regions in Asia and the tropical Pacific compared to a mean water vapor content of ~5 ppmv. In addition to this main transport pathway from the Asian monsoon anticyclone to the east along the subtropical jet and subsequent transport into the northern lower stratosphere, a second horizontal transport pathway out of the anticyclone to the west into the tropics (TTL) is found in agreement with MIPAS HCFC-22 measurements.

scholarly journals Long-range transport pathways of tropospheric source gases originating in Asia into the northern lower stratosphere during the Asian monsoon season 2012

2016 ◽  
Vol 16 (23) ◽  
pp. 15301-15325 ◽  
Author(s):  
Bärbel Vogel ◽  
Gebhard Günther ◽  
Rolf Müller ◽  
Jens-Uwe Grooß ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Monsoon Season ◽  
Lagrangian Model ◽  
Transport Pathway ◽  
Air Masses ◽  
Horizontal Transport ◽  
Source Regions ◽  
Subtropical Jet

Abstract. Global simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) using artificial tracers of air mass origin are used to analyze transport mechanisms from the Asian monsoon region into the lower stratosphere. In a case study, the transport of air masses from the Asian monsoon anticyclone originating in India/China by an eastward-migrating anticyclone which broke off from the main anticyclone on 20 September 2012 and filaments separated at the northeastern flank of the anticyclone are analyzed. Enhanced contributions of young air masses (younger than 5 months) are found within the separated anticyclone confined at the top by the thermal tropopause. Further, these air masses are confined by the anticyclonic circulation and, on the polar side, by the subtropical jet such that the vertical structure resembles a bubble within the upper troposphere. Subsequently, these air masses are transported eastwards along the subtropical jet and enter the lower stratosphere by quasi-horizontal transport in a region of double tropopauses most likely associated with Rossby wave breaking events. As a result, thin filaments with enhanced signatures of tropospheric trace gases were measured in the lower stratosphere over Europe during the TACTS/ESMVal campaign in September 2012 in very good agreement with CLaMS simulations. Our simulations demonstrate that source regions in Asia and in the Pacific Ocean have a significant impact on the chemical composition of the lower stratosphere of the Northern Hemisphere. Young, moist air masses, in particular at the end of the monsoon season in September/October 2012, flooded the extratropical lower stratosphere in the Northern Hemisphere with contributions of up to  ≈  30 % at 380 K (with the remaining fraction being aged air). In contrast, the contribution of young air masses to the Southern Hemisphere is much lower. At the end of October 2012, approximately 1.5 ppmv H2O is found in the lower Northern Hemisphere stratosphere (at 380 K) from source regions both in Asia and in the tropical Pacific compared to a mean water vapor content of  ≈  5 ppmv. In addition to this main transport pathway from the Asian monsoon anticyclone to the east along the subtropical jet and subsequent transport into the northern lower stratosphere, a second horizontal transport pathway out of the anticyclone to the west into the tropics (TTL) is found in agreement with MIPAS HCFC-22 measurements.

scholarly journals Impact of different Asian source regions on the composition of the Asian monsoon anticyclone and of the extratropical lowermost stratosphere

2015 ◽  
Vol 15 (23) ◽  
pp. 13699-13716 ◽  
Author(s):  
B. Vogel ◽  
G. Günther ◽  
R. Müller ◽  
J.-U. Grooß ◽  
M. Riese
Keyword(s):  
Chemical Composition ◽  
Southeast Asia ◽  
Asian Monsoon ◽  
Monsoon Season ◽  
Intraseasonal Variability ◽  
Air Masses ◽  
Northern India ◽  
Source Regions ◽  
The Tropics ◽  
Emission Tracers

Abstract. The impact of different boundary layer source regions in Asia on the chemical composition of the Asian monsoon anticyclone, considering its intraseasonal variability in 2012, is analysed by simulations of the Chemical Lagrangian Model of the Stratosphere (CLaMS) using artificial emission tracers. The horizontal distribution of simulated CO, O3, and artificial emission tracers for India/China are in good agreement with patterns found in satellite measurements of O3 and CO by the Aura Microwave Limb Sounder (MLS). Using in addition, correlations of artificial emission tracers with potential vorticity demonstrates that the emission tracer for India/China is a very good proxy for spatial distribution of trace gases within the Asian monsoon anticyclone. The Asian monsoon anticyclone constitutes a horizontal transport barrier for emission tracers and is highly variable in location and shape. From the end of June to early August, a northward movement of the anticyclone and, during September, a strong broadening of the spatial distribution of the emission tracer for India/China towards the tropics are found. In addition to the change of the location of the anticyclone, the contribution of different boundary source regions to the composition of the Asian monsoon anticyclone in the upper troposphere strongly depends on its intraseasonal variability and is therefore more complex than hitherto believed. The largest contributions to the composition of the air mass in the anticyclone are found from northern India and Southeast Asia at a potential temperature of 380 K. In the early (mid-June to mid-July) and late (September) period of the 2012 monsoon season, contributions of emissions from Southeast Asia are highest; in the intervening period (early August), emissions from northern India have the largest impact. Our findings show that the temporal variation of the contribution of different convective regions is imprinted in the chemical composition of the Asian monsoon anticyclone. Air masses originating in Southeast Asia are found both within and outside of the Asian monsoon anticyclone because these air masses experience, in addition to transport within the anticyclone, upward transport at the southeastern flank of the anticyclone and in the tropics. Subsequently, isentropic poleward transport of these air masses occurs at around 380 K with the result that the extratropical lowermost stratosphere in the Northern Hemisphere is flooded by the end of September with air masses originating in Southeast Asia. Even after the breakup of the anticyclonic circulation (around the end of September), significant contributions of air masses originating in India/China are still found in the upper troposphere over Asia. Our results demonstrate that emissions from India, China, and Southeast Asia have a significant impact on the chemical composition of the lowermost stratosphere of the Northern Hemisphere, in particular at the end of the monsoon season in September/October 2012.

scholarly journals Impact of the Asian monsoon on the extratropical lower stratosphere: trace gas observations during TACTS over Europe 2012

2015 ◽  
Vol 15 (23) ◽  
pp. 34765-34812
Author(s):  
S. Müller ◽  
P. Hoor ◽  
H. Bozem ◽  
E. Gute ◽  
B. Vogel ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Trace Gas ◽  
Boreal Summer ◽  
Monsoon Circulation ◽  
Transport Pathway ◽  
Air Masses ◽  
Time Period ◽  
Asian Summer

Abstract. The transport of air masses originating from the Asian monsoon anticyclone into the extratropical upper troposphere and lower stratosphere (Ex-UTLS) above potential temperatures Θ = 380 K was identified during the HALO aircraft mission TACTS in August and September 2012. In-situ measurements of CO, O3 and N2O during TACTS Flight 2 on the 30 August 2012 show the irreversible mixing of aged with younger (originating from the troposphere) stratospheric air masses within the Ex-UTLS. Backward trajectories calculated with the trajetory module of the CLaMS model indicate that these tropospherically affected air masses originate from the Asian monsoon anticyclone. From the monsoon circulation region these air masses are quasi-isentropically transported above Θ = 380 K into the Ex-UTLS where they subsequently mix with stratospheric air masses. The overall trace gas distribution measured during TACTS shows that this transport pathway has a significant impact on the Ex-UTLS during boreal summer and autumn. This leads to an intensification of the tropospheric influence on the Ex-UTLS with ΔΘ > 30 K (relative to the tropopause) within three weeks during the TACTS mission. In the same time period a weakening of the tropospheric influence on the lowermost stratosphere (LMS) is determined. Therefore, the study shows that the transport of air masses originating from the Asian summer monsoon region within the lower stratosphere above Θ = 380 K is of major importance for the change of the chemical composition of the Ex-UTLS from summer to autumn.

scholarly journals Impact of the Asian monsoon on the extratropical lower stratosphere: trace gas observations during TACTS over Europe 2012

2016 ◽  
Vol 16 (16) ◽  
pp. 10573-10589 ◽  
Author(s):  
Stefan Müller ◽  
Peter Hoor ◽  
Heiko Bozem ◽  
Ellen Gute ◽  
Bärbel Vogel ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Trace Gas ◽  
Boreal Summer ◽  
Monsoon Circulation ◽  
Transport Pathway ◽  
Air Masses ◽  
Time Period

Abstract. The transport of air masses originating from the Asian monsoon anticyclone into the extratropical upper troposphere and lower stratosphere (Ex-UTLS) above potential temperatures Θ =  380 K was identified during the HALO aircraft mission TACTS in August and September 2012. In situ measurements of CO, O3 and N2O during TACTS flight 2 on 30 August 2012 show the irreversible mixing of aged stratospheric air masses with younger (recently transported from the troposphere) ones within the Ex-UTLS. Backward trajectories calculated with the trajectory module of CLaMS indicate that these tropospherically affected air masses originate from the Asian monsoon anticyclone. These air masses are subsequently transported above potential temperatures Θ =  380 K from the monsoon circulation region into the Ex-UTLS, where they subsequently mix with stratospheric air masses. The overall trace gas distribution measured during TACTS shows that this transport pathway had affected the chemical composition of the Ex-UTLS during boreal summer and autumn 2012. This leads to an intensification of the tropospheric influence on the extratropical lower stratosphere with PV  >  8 pvu within 3 weeks during the TACTS mission. During the same time period a weakening of the tropospheric influence on the lowermost stratosphere (LMS) is determined. The study shows that the transport of air masses originating from the Asian summer monsoon region within the lower stratosphere affects the change in the chemical composition of the Ex-UTLS over Europe and thus contributes to the flushing of the LMS during summer 2012.

scholarly journals Transport Pathways and Potential Source Regions of PM2.5 on the West Coast of Bohai Bay during 2009–2018

Atmosphere ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 345 ◽  
Author(s):  
Tianyi Hao ◽  
Ziying Cai ◽  
Shucheng Chen ◽  
Suqin Han ◽  
Qing Yao ◽  
...  
Keyword(s):  
West Coast ◽  
Natural Source ◽  
Anthropogenic Source ◽  
Bohai Bay ◽  
Transport Pathway ◽  
The West ◽  
Transport Pathways ◽  
Air Masses ◽  
Source Regions ◽  
Potential Source

Mass concentration data for particulate matter with an aerodynamic diameter less than or equal to 2.50 μm (PM2.5) combined with backward trajectory cluster analysis, potential source contribution function (PSCF), and concentration weighted trajectory (CWT) methods were used to investigate the transport pathways and potential source regions of PM2.5 on the west coast of Bohai Bay from 2009 to 2018. Two pathways responsible for the transportation of high PM2.5 levels were identified, namely a southerly pathway and a northwesterly pathway. The southerly pathway represented the major transport pathway of PM2.5 for all seasons. As a regional transport pathway, it had the greatest impact in winter, followed by autumn. The southerly transport pathway passed over the Shandong and Hebei provinces before reaching Tianjin: Air masses were transported within the boundary layer (below 925 hPa), representing a slow-moving air flow. The northwesterly pathway mostly occurred in winter and autumn and passed over desert and semidesert regions in Outer Mongolia, the sand lands of Inner Mongolia, and Hebei. The air masses associated with the northwesterly pathway represented fast-moving airflows responsible for long-range transportation of PM2.5. Two potential source regions that contributed to high PM2.5 loadings on the west coast of Bohai Bay were identified, “southerly source regions” and “northwesterly source regions”. The southerly source regions, with weighted CWT (WCWT) values in winter greater than 140.00 μg/m3, were anthropogenic source regions, including southern Hebei, western Shandong, eastern Henan, northern Anhui, and northern Jiangsu. The northwesterly source regions, with WCWT values in winter of 80.00–140.00 μg/m3, were natural source regions, encompassing central Inner Mongolia and southern Mongolia. In addition, the southerly transport pathway passed though anthropogenic source regions, while the northwesterly transport pathway passed though natural source regions. The impacts of anthropogenic source regions on PM2.5 loadings on the west coast of Bohai Bay were greater than those of natural source regions.

scholarly journals Fast transport from Southeast Asia boundary layer sources to northern Europe: rapid uplift in typhoons and eastward eddy shedding of the Asian monsoon anticyclone

2014 ◽  
Vol 14 (23) ◽  
pp. 12745-12762 ◽  
Author(s):  
B. Vogel ◽  
G. Günther ◽  
R. Müller ◽  
J.-U. Grooß ◽  
P. Hoor ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Southeast Asia ◽  
Asian Monsoon ◽  
Northern Europe ◽  
Transport Pathway ◽  
West Pacific ◽  
Air Masses ◽  
Fast Transport ◽  
Rapid Uplift ◽  
Eddy Shedding

Abstract. Enhanced tropospheric trace gases such as CO, CH4 and H2O and reduced stratospheric O3 were measured in situ in the lowermost stratosphere over northern Europe on 26 September 2012 during the TACTS aircraft campaign. The measurements indicate that these air masses clearly differ from the stratospheric background. The calculation of 40-day backward trajectories with the trajectory module of the CLaMS model shows that these air masses are affected by the Asian monsoon anticyclone. Some air masses originate from the boundary layer in Southeast Asia/West Pacific and are rapidly lifted (1–2 days) within a typhoon up to the outer edge of the Asian monsoon anticyclone. Afterwards, the air parcels are entrained by the anticyclonic circulation of the Asian monsoon. The subsequent long-range transport (8–14 days) of enhanced water vapour and pollutants to the lowermost stratosphere in northern Europe is driven by eastward transport of tropospheric air from the Asian monsoon anticyclone caused by an eddy shedding event. We found that the combination of rapid uplift by a typhoon and eastward eddy shedding from the Asian monsoon anticyclone is a novel fast transport pathway that may carry boundary emissions from Southeast Asia/West Pacific within approximately 5 weeks to the lowermost stratosphere in northern Europe.

scholarly journals Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

2017 ◽  
Vol 17 (11) ◽  
pp. 7055-7066 ◽  
Author(s):  
Felix Ploeger ◽  
Paul Konopka ◽  
Kaley Walker ◽  
Martin Riese
Keyword(s):  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Monsoon Circulation ◽  
Pollution Transport ◽  
Chemistry Transport Model ◽  
Transport Pathways ◽  
Air Mass ◽  
Mass Fractions ◽  
The Tropics

Abstract. Pollution transport from the surface to the stratosphere within the Asian monsoon circulation may cause harmful effects on stratospheric chemistry and climate. Here, we investigate air mass transport from the monsoon anticyclone into the stratosphere using a Lagrangian chemistry transport model. We show how two main transport pathways from the anticyclone emerge: (i) into the tropical stratosphere (tropical pipe), and (ii) into the Northern Hemisphere (NH) extratropical lower stratosphere. Maximum anticyclone air mass fractions reach around 5 % in the tropical pipe and 15 % in the extratropical lowermost stratosphere over the course of a year. The anticyclone air mass fraction correlates well with satellite hydrogen cyanide (HCN) and carbon monoxide (CO) observations, confirming that pollution is transported deep into the tropical stratosphere from the Asian monsoon anticyclone. Cross-tropopause transport occurs in a vertical chimney, but with the pollutants transported quasi-horizontally along isentropes above the tropopause into the tropics and NH.

scholarly journals Water vapor increase in the lower stratosphere of the Northern Hemisphere due to the Asian monsoon anticyclone observed during the TACTS/ESMVal campaigns

2018 ◽  
Vol 18 (4) ◽  
pp. 2973-2983 ◽  
Author(s):  
Christian Rolf ◽  
Bärbel Vogel ◽  
Peter Hoor ◽  
Armin Afchine ◽  
Gebhard Günther ◽  
...  
Keyword(s):  
Water Vapor ◽  
Northern Hemisphere ◽  
Asian Monsoon ◽  
Eastern China ◽  
Potential Temperature ◽  
Monsoon Region ◽  
Asian Monsoon Region ◽  
Air Mass ◽  
Air Masses ◽  
The Impact

Abstract. The impact of air masses originating in Asia and influenced by the Asian monsoon anticyclone on the Northern Hemisphere stratosphere is investigated based on in situ measurements. A statistically significant increase in water vapor (H2O) of about 0.5 ppmv (11 %) and methane (CH4) of up to 20 ppbv (1.2 %) in the extratropical stratosphere above a potential temperature of 380 K was detected between August and September 2012 during the HALO aircraft missions Transport and Composition in the UT/LMS (TACTS) and Earth System Model Validation (ESMVal). We investigate the origin of the increased water vapor and methane using the three-dimensional Chemical Lagrangian Model of the Stratosphere (CLaMS). We assign the source of the moist air masses in the Asian region (northern and southern India, eastern China, southeast Asia, and the tropical Pacific) based on tracers of air mass origin used in CLaMS. The water vapor increase is correlated with an increase of the simulated Asian monsoon air mass contribution from about 10 % in August to about 20 % in September, which corresponds to a doubling of the influence from the Asian monsoon region. Additionally, back trajectories starting at the aircraft flight paths are used to differentiate transport from the Asian monsoon anticyclone and other source regions by calculating the Lagrangian cold point (LCP). The geographic location of the LCPs, which indicates the region where the set point of water vapor mixing ratio along these trajectories occurs, can be predominantly attributed to the Asian monsoon region.

scholarly journals Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

2017 ◽  
Author(s):  
Felix Ploeger ◽  
Paul Konopka ◽  
Kaley Walker ◽  
Martin Riese
Keyword(s):  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Monsoon Circulation ◽  
Pollution Transport ◽  
Chemistry Transport Model ◽  
Transport Pathways ◽  
Air Mass ◽  
Mass Fractions ◽  
The Tropics

Abstract. Pollution transport from the surface to the stratosphere within the Asian monsoon circulation may cause harmful effects on stratospheric chemistry and climate. Here, we investigate air mass transport from the monsoon anticyclone into the stratosphere using a Lagrangian chemistry transport model. We show how two main transport pathways from the anticyclone emerge: (i) into the tropical stratosphere (tropical pipe), and (ii) into the Northern hemisphere (NH) extra-tropical lower stratosphere. Maximum anticyclone air mass fractions reach around 5 % in the tropical pipe and 15 % in the extra-tropical lowermost stratosphere over the course of a year. The anticyclone air mass fraction correlates well with satellite hydrogen cyanide (HCN) and carbon monoxide (CO) observations, corroborating that pollution is transported deep into the tropical stratosphere from the Asian monsoon anticyclone. Cross-tropopause transport occurs in a vertical chimney, but with the emissions transported quasi-horizontally along isentropes above the tropopause into the tropics and NH.

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