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Martin Riese - One of the best experts on this subject based on the ideXlab platform.
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Quantifying pollution transport from the Asian monsoon Anticyclone into the lower stratosphere
Atmospheric Chemistry and Physics, 2017Co-Authors: Felix Ploeger, Paul Konopka, Kaley A. Walker, Martin RieseAbstract: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.
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Quantifying pollution transport from the Asian monsoon Anticyclone into the lower stratosphere
2017Co-Authors: Felix Ploeger, Paul Konopka, Kaley Walker, Martin RieseAbstract: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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observations of pan and its confinement in the asian summer monsoon Anticyclone in high spatial resolution
Atmospheric Chemistry and Physics, 2016Co-Authors: Jörn Ungermann, Felix Ploeger, Barbel Vogel, Rolf Muller, Mandfred Ern, Martin Kaufmann, R Spang, Martin RieseAbstract:Abstract. This paper presents an analysis of trace gases in the Asian summer monsoon (ASM) region on the basis of observations by the CRISTA infrared limb sounder taken in low-earth orbit in August 1997. The spatially highly resolved measurements of peroxyacetyl nitrate (PAN) and O3 allow a detailed analysis of an eddy-shedding event of the ASM Anticyclone. We identify enhanced PAN volume mixing ratios (VMRs) within the main Anticyclone and within the eddy, which are suitable as a tracer for polluted air originating in India and China. Plotting the retrieved PAN VMRs against potential vorticity (PV) and potential temperature reveals that the PV value at which the PAN VMRs exhibit the strongest decrease with respect to PV increases with potential temperature. These PV values might be used to identify the extent of the ASM. Using temperature values also derived from CRISTA measurements, we also computed the location of the thermal tropopause according to the WMO criterion and find that it confines the PAN anomaly vertically within the main ASM Anticyclone. In contrast, the shed eddy exhibits enhanced PAN VMRs for 1 to 2 km above the thermal tropopause. Using the relationship between PAN as a tropospheric tracer and O3 as a stratospheric tracer to identify mixed air parcels, we further found the Anticyclone to contain few such air parcels, whereas the region between the Anticyclone and the eddy as well as the eddy itself contains many mixed air parcels. In combination, this implies that while the Anticyclone confines polluted air masses well, eddy shedding provides a very rapid horizontal transport pathway of Asian pollution into the extratropical lowermost stratosphere with a timescale of only a few days.
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impact of different asian source regions on the composition of the asian monsoon Anticyclone and of the extratropical lowermost stratosphere
Atmospheric Chemistry and Physics, 2015Co-Authors: Barbel Vogel, G Gunther, Rolf Muller, J U Groos, Martin RieseAbstract: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.
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a potential vorticity based determination of the transport barrier in the asian summer monsoon Anticyclone
Atmospheric Chemistry and Physics, 2015Co-Authors: Felix Ploeger, Paul Konopka, Martin Riese, Rolf Muller, J U Groos, C. Gottschling, Sabine Griessbach, Fred Stroh, G Guenther, Mengchu TaoAbstract:Abstract. The Asian summer monsoon provides an important pathway of tropospheric source gases and pollution into the lower stratosphere. This transport is characterized by deep convection and steady upwelling, combined with confinement inside a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS). In this paper, we show that a barrier to horizontal transport along the 380 K isentrope in the monsoon Anticyclone can be determined from a local maximum in the gradient of potential vorticity (PV), following methods developed for the polar vortex (e.g., Nash et al., 1996). The monsoon Anticyclone is dynamically highly variable and the maximum in the PV gradient is weak, such that additional constraints are needed (e.g., time averaging). Nevertheless, PV contours in the monsoon Anticyclone agree well with contours of trace gas mixing ratios (CO, O3) and mean age from model simulations with a Lagrangian chemistry transport model (CLaMS) and satellite observations from the Microwave Limb Sounder (MLS) instrument. Hence, the PV-based transport barrier reflects the separation between air inside the core of the Anticyclone and the background atmosphere well. For the summer season 2011 we find an average PV value of 3.6 PVU for the transport barrier in the Anticyclone on the 380 K isentrope.
C. D. Boone - One of the best experts on this subject based on the ideXlab platform.
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Chemical isolation in the Asian monsoon Anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS) data
Atmospheric Chemistry and Physics, 2008Co-Authors: M. Park, W. J. Randel, L. K. Emmons, P. F. Bernath, K. A. Walker, C. D. BooneAbstract:Evidence of chemical isolation in the Asian monsoon Anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June?August) of 2004?2006. Carbon monoxide (CO) shows a broad maximum over the monsoon Anticyclone region in the upper troposphere and lower stratosphere (UTLS); these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the Anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13?15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl) exhibit decreased values inside the Anticyclone between ~12?20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the Anticyclone. The relative enhancements of tropospheric species inside the Anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air) suggest relatively rapid transport of fresh emissions up to the tropopause level inside the Anticyclone.
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Chemical Isolation in the Asian monsoon Anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS) data
Atmospheric Chemistry and Physics Discussions, 2007Co-Authors: M. Park, W. J. Randel, L. K. Emmons, P. F. Bernath, K. A. Walker, C. D. BooneAbstract:Evidence of chemical isolation in the Asian monsoon Anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June?August) of 2004?2006. Carbon monoxide (CO) shows a broad maximum over the monsoon Anticyclone region in the upper troposphere and lower stratosphere (UTLS); these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the Anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13?15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl) exhibit decreased values inside the Anticyclone between ~12?20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the Anticyclone. The relative enhancements of tropospheric species inside the Anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air) suggest relatively rapid transport of fresh emissions up to tropopause level inside the Anticyclone.
Felix Ploeger - One of the best experts on this subject based on the ideXlab platform.
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Quantifying pollution transport from the Asian monsoon Anticyclone into the lower stratosphere
Atmospheric Chemistry and Physics, 2017Co-Authors: Felix Ploeger, Paul Konopka, Kaley A. Walker, Martin RieseAbstract: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.
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Quantifying pollution transport from the Asian monsoon Anticyclone into the lower stratosphere
2017Co-Authors: Felix Ploeger, Paul Konopka, Kaley Walker, Martin RieseAbstract: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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observations of pan and its confinement in the asian summer monsoon Anticyclone in high spatial resolution
Atmospheric Chemistry and Physics, 2016Co-Authors: Jörn Ungermann, Felix Ploeger, Barbel Vogel, Rolf Muller, Mandfred Ern, Martin Kaufmann, R Spang, Martin RieseAbstract:Abstract. This paper presents an analysis of trace gases in the Asian summer monsoon (ASM) region on the basis of observations by the CRISTA infrared limb sounder taken in low-earth orbit in August 1997. The spatially highly resolved measurements of peroxyacetyl nitrate (PAN) and O3 allow a detailed analysis of an eddy-shedding event of the ASM Anticyclone. We identify enhanced PAN volume mixing ratios (VMRs) within the main Anticyclone and within the eddy, which are suitable as a tracer for polluted air originating in India and China. Plotting the retrieved PAN VMRs against potential vorticity (PV) and potential temperature reveals that the PV value at which the PAN VMRs exhibit the strongest decrease with respect to PV increases with potential temperature. These PV values might be used to identify the extent of the ASM. Using temperature values also derived from CRISTA measurements, we also computed the location of the thermal tropopause according to the WMO criterion and find that it confines the PAN anomaly vertically within the main ASM Anticyclone. In contrast, the shed eddy exhibits enhanced PAN VMRs for 1 to 2 km above the thermal tropopause. Using the relationship between PAN as a tropospheric tracer and O3 as a stratospheric tracer to identify mixed air parcels, we further found the Anticyclone to contain few such air parcels, whereas the region between the Anticyclone and the eddy as well as the eddy itself contains many mixed air parcels. In combination, this implies that while the Anticyclone confines polluted air masses well, eddy shedding provides a very rapid horizontal transport pathway of Asian pollution into the extratropical lowermost stratosphere with a timescale of only a few days.
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a potential vorticity based determination of the transport barrier in the asian summer monsoon Anticyclone
Atmospheric Chemistry and Physics, 2015Co-Authors: Felix Ploeger, Paul Konopka, Martin Riese, Rolf Muller, J U Groos, C. Gottschling, Sabine Griessbach, Fred Stroh, G Guenther, Mengchu TaoAbstract:Abstract. The Asian summer monsoon provides an important pathway of tropospheric source gases and pollution into the lower stratosphere. This transport is characterized by deep convection and steady upwelling, combined with confinement inside a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS). In this paper, we show that a barrier to horizontal transport along the 380 K isentrope in the monsoon Anticyclone can be determined from a local maximum in the gradient of potential vorticity (PV), following methods developed for the polar vortex (e.g., Nash et al., 1996). The monsoon Anticyclone is dynamically highly variable and the maximum in the PV gradient is weak, such that additional constraints are needed (e.g., time averaging). Nevertheless, PV contours in the monsoon Anticyclone agree well with contours of trace gas mixing ratios (CO, O3) and mean age from model simulations with a Lagrangian chemistry transport model (CLaMS) and satellite observations from the Microwave Limb Sounder (MLS) instrument. Hence, the PV-based transport barrier reflects the separation between air inside the core of the Anticyclone and the background atmosphere well. For the summer season 2011 we find an average PV value of 3.6 PVU for the transport barrier in the Anticyclone on the 380 K isentrope.
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A PV-based determination of the transport barrier in the Asian summer monsoon Anticyclone
Atmospheric Chemistry and Physics Discussions, 2015Co-Authors: Felix Ploeger, Paul Konopka, Martin Riese, Rolf Muller, C. Gottschling, Sabine Griessbach, Jens-uwe Grooß, Gebhard Günther, Fred Stroh, Jörn UngermannAbstract:Abstract. The Asian summer monsoon provides an important pathway of tropospheric source gases and pollution into the lower stratosphere. This transport is characterized by deep convection and steady upwelling, combined with confinement inside a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS). In this paper, we show that a barrier to horizontal transport along the 380 K isentrope in the monsoon Anticyclone can be determined from the potential vorticity (PV) field, following the polar vortex criterion by Nash et al. (1996). Due to large dynamic variability of the Anticyclone, the corresponding maximum in the PV gradient is weak and additional constraints are needed (e.g., time averaging). Notwithstanding, PV contours in the monsoon Anticyclone agree well with contours of trace gas mixing ratios (CO, O3) and mean age from model simulations with a Lagrangian chemistry transport model (CLaMS) and MLS satellite observations. Hence, the PV-based transport barrier reflects the separation between air inside the Anticyclone core and the background atmosphere well. For the summer season 2011 we find an average PV value of 3.6 PVU for the transport barrier in the Anticyclone on the 380 K isentrope.
Alexander Gershunov - One of the best experts on this subject based on the ideXlab platform.
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Pacific cyclonic and anticyclonic transients in a global warming context: possible consequences for Western North American daily precipitation and temperature extremes
Climate Dynamics, 2008Co-Authors: Alice Favre, Alexander GershunovAbstract:Trajectories of surface cyclones and Anticyclones were constructed using an automated scheme by tracking local minima and maxima of mean daily sea level pressure data in the NCEP-NCAR reanalysis and the Centre National de Recherches Météorologiques coupled global climate Model (CNRM-CM3) SRES A2 integration. Mid-latitude lows and highs traveling in the North Pacific were tracked and daily frequencies were gridded. Transient activity in the CNRM-CM3 historical simulation (1950–1999) was validated against reanalysis. The GCM correctly reproduces winter trajectories as well as mean geographical distributions of cyclones and Anticyclones over the North Pacific in spite of a general under-estimation of cyclones' frequency. On inter-annual time scales, frequencies of cyclones and Anticyclones vary in accordance with the Aleutian Low (AL) strength. When the AL is stronger (weaker), cyclones are more (less) numerous over the central and eastern North Pacific, while Anticyclones are significantly less (more) numerous over this region. The action of transient cyclones and Anticyclones over the central and eastern North Pacific determines seasonal climate over the West Coast of North America, and specifically, winter weather over California. Relationships between winter cyclone/Anticyclone behavior and daily precipitation/cold temperature extremes over Western North America (the West) were examined and yielded two simple indices summarizing North Pacific transient activity relevant to regional climates. These indices are strongly related to the observed inter-annual variability of daily precipitation and cold temperature extremes over the West as well as to large scale seasonally averaged near surface climate conditions (e.g., air temperature at 2 m and wind at 10 m). In fact, they represent the synoptic links that accomplish the teleconnections. Comparison of patterns derived from NCEP-NCAR and CNRM-CM3 revealed that the model reproduces links between cyclone/Anticyclone frequencies over the Northeastern Pacific and extra-tropical climate conditions but is deficient in relation to tropical climate variability. The connections between these synoptic indices and Western weather are well reproduced by the model. Under advanced global warming conditions, that is, the last half of the century, the model predicts a significant reduction of cyclonic transients throughout the mid-latitude North Pacific with the exception of the far northern and northeastern domains. Anticyclonic transients respond somewhat more regionally but consistently to strong greenhouse forcing, with notably fewer Anticyclones over the Okhotsk/Kamchatka sector and generally more Anticyclones in the Northeastern Pacific. These modifications of synoptic weather result in regional feedbacks, that is, regional synoptic alterations of the anthropogenic warming signal around the North Pacific. In the eastern Pacific, for example, synoptic feedbacks, having to do especially with the northward shift of the eastern Pacific storm-track (responding, in turn, to a weaker equator-to-pole temperature gradient), are favorable to more anticyclonic conditions off the American mid-latitude west coast and more cyclonic conditions at higher latitudes. These circulation feedbacks further reduce the equator-to-pole temperature gradient by favoring high-latitude mean winter warming especially over a broad wedge of the Arctic north of the Bering Sea and moderating the warming along the mid-latitude west coast of north America while also reducing precipitation frequencies from California to Northern Mexico.
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Extra-Tropical cyclonic/anticyclonic activity in North-Eastern Pacific and air temperature extremes in Western North America
Climate Dynamics, 2006Co-Authors: Alice Favre, Alexander GershunovAbstract:Synoptic extra-tropical cyclone and Anticyclone trajectories have been constructed from mean daily sea level pressure (SLP) data using a new automated scheme. Frequency, intensity and trajectory characteristics of these transients have been summarized to form indices describing wintertime cyclonic and anticyclonic activity over the North-Eastern Pacific (east of 170°W) during 1950 2001. During this period, the strength of Anticyclones gradually diminished and their frequency became more variable, while cyclones intensified in a discrete shift with deeper lows and further southerly trajectories occurring since the mid-1970s. These changes in synoptic transients translate into anomalously low seasonal mean SLP in the Aleutian Low, a low-level circulation anomaly consistent with the positive phase of the North Pacific Decadal Oscillation, with positive sea surface temperature (SST) anomalies along the west coast of North America and negative in the central North Pacific Ocean. A link between cyclonic/anticyclonic activity and tropical SST anomalies also exists, but this link only becomes significant after the mid-1970s, a period that coincides with more southerly cyclone trajectories. Southward excursions of mid-latitude cyclones during El Niño/positive NPO winters accomplish the northward advection of tropical air and discourage the southward penetration of polar air masses associated with transient Anticyclones. Naturally, these changes in cyclonic/anticyclonic activity directly impact surface air temperatures, especially at night. We document these profound impacts on observed wintertime minimum temperatures over Western North America.
M. Park - One of the best experts on this subject based on the ideXlab platform.
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Chemical isolation in the Asian monsoon Anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS) data
Atmospheric Chemistry and Physics, 2008Co-Authors: M. Park, W. J. Randel, L. K. Emmons, P. F. Bernath, K. A. Walker, C. D. BooneAbstract:Evidence of chemical isolation in the Asian monsoon Anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June?August) of 2004?2006. Carbon monoxide (CO) shows a broad maximum over the monsoon Anticyclone region in the upper troposphere and lower stratosphere (UTLS); these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the Anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13?15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl) exhibit decreased values inside the Anticyclone between ~12?20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the Anticyclone. The relative enhancements of tropospheric species inside the Anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air) suggest relatively rapid transport of fresh emissions up to the tropopause level inside the Anticyclone.
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Chemical Isolation in the Asian monsoon Anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS) data
Atmospheric Chemistry and Physics Discussions, 2007Co-Authors: M. Park, W. J. Randel, L. K. Emmons, P. F. Bernath, K. A. Walker, C. D. BooneAbstract:Evidence of chemical isolation in the Asian monsoon Anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June?August) of 2004?2006. Carbon monoxide (CO) shows a broad maximum over the monsoon Anticyclone region in the upper troposphere and lower stratosphere (UTLS); these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the Anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13?15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl) exhibit decreased values inside the Anticyclone between ~12?20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the Anticyclone. The relative enhancements of tropospheric species inside the Anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air) suggest relatively rapid transport of fresh emissions up to tropopause level inside the Anticyclone.
