Results from a comparison of HCN measurements and Lagrangian backtrajectory analyses in the Asian Summer Monsoon Anticyclone

2020 ◽  
Author(s):  
Yun Li ◽  
Bärbel Vogel ◽  
Felix Plöger ◽  
Silvia Bucci ◽  
Bernard Legras ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Atmospheric Composition ◽  
Convective Activity ◽  
Mixing Ratios ◽  
Research Aircraft ◽  
Asian Summer ◽  
Good Tracer

<p>The StratoClim aircraft field campaign took place from Kathmandu, Nepal, in summer 2017 in<br>order to study the atmospheric composition, chemistry, and dynamics in the Asian Summer<br>Monsoon Anticyclone (ASMA) which is known to transport surface emissions to the mid-latitude<br>lower stratosphere and the stratosphere worldwide. Hydrogen cyanide (HCN) which is primarily<br>emitted from biomass burning and has a UTLS lifetime on the order of 1-2 years is a good tracer for<br>biomass burning import into the lower and free stratosphere.<br>HCN in the ASM Upper Troposphere and Lower Stratosphere (UTLS) was measured in-situ<br>employing the Chemical-Ionization Time-of-Flight Mass Spectrometer FUNMASS on board the<br>high-altitude research aircraft M55-Geophysica. The observed HCN mixing ratios in and above the<br>ASMA exhibit interesting vertical and horizontal signatures around the tropopause as well as in the<br>LS probably resulting from convective activity or air mass origin (AMO). We here compare<br>measured HCN to Lagrangian simulations by the ClaMS and TRACZILLA models which employ<br>two different approaches to represent higher-reaching convective events. The simulations succeed to<br>track some of the observed HCN features back to convective activity or AMO. The quality of the<br>reproduction and further outcomes on the atmospheric relevance will be discussed in the<br>presentation.</p>

Investigating the roles of the Asian monsoon, the North American monsoon, and Hurricanes for efficient transport of chlorinated short-lived species to the UTLS based on in situ observations

2021 ◽  
Author(s):  
Valentin Lauther ◽  
Johannes Wintel ◽  
Emil Gerhardt ◽  
Andrea Rau ◽  
Peter Hoor ◽  
...  
Keyword(s):  
High Altitude ◽  
Central America ◽  
North American ◽  
Asian Summer Monsoon ◽  
North American Monsoon ◽  
Mixing Ratios ◽  
The North ◽  
Asian Summer ◽  
Efficient Transport

<p>Chlorinated very short-lived substances (Cl-VSLS) are not controlled by the Montreal Protocol but the recent emission increase of the Cl-VSLS CH<sub>2</sub>Cl<sub>2</sub> (Dichloromethane) and CHCl<sub>3</sub> (Chloroform) is believed to significantly increase the stratospheric chlorine loading from VSLS. Provided efficient transport of Cl-VSLS from the source region into the stratosphere further emission increases could ultimately even cause a significant delay of the predicted recovery date of the ozone layer to pre-1980 values. During the WISE (Wave-driven ISentropic Exchange) campaign in autumn 2017 excessive probing of the UTLS (upper troposphere lower stratosphere) region above Western Europe and the Atlantic Ocean was conducted from aboard the HALO (High Altitude and Long range) research aircraft. We use real-time in situ WISE measurements of CH<sub>2</sub>Cl<sub>2</sub> and CHCl<sub>3</sub> from HAGAR-V (High Altitude Gas AnalyzeR – 5 channel version) in correlation with N<sub>2</sub>O from UMAQS (University of Mainz Airborne QCL Spectrometer), as well as CLaMS (Chemical Lagrangian Model of the Stratosphere) global 3-dimensional simulations of air mass origin tracers and backward trajectories to identify the most efficient transport mechanisms for Cl-VSLS entering the LS region in northern hemispheric summer.</p><p>The WISE measurements reveal two distinct transport pathways into the UTLS region of particularly CH<sub>2</sub>Cl<sub>2</sub>-rich and CH<sub>2</sub>Cl<sub>2</sub>-poor air. CH<sub>2</sub>Cl<sub>2</sub>-rich air could be identified to be transported by the Asian summer monsoon within about 4-10 weeks from its source regions in Asia into the stratosphere above the Atlantic Ocean at around 380 K and above. CH<sub>2</sub>Cl<sub>2</sub>-poor air could be identified to be mainly uplifted to potential temperatures of about 365 K by the North American monsoon above the region of Central America with transport times of only 2-5 weeks. In addition, we could link backward trajectories of CH<sub>2</sub>Cl<sub>2</sub>-poor air in the LS region to be uplifted by the category 5 hurricane Maria in September 2017. Based on all analyzed WISE measurements, we found that almost all young (transport time < 4 months) air masses were uplifted either above Asia or above Central America, emphasizing not only the impact of the Asian summer monsoon on the stratospheric tracer distribution but also that of the North American monsoon and hurricanes.</p><p>The measurements of both CH<sub>2</sub>Cl<sub>2</sub> and CHCl<sub>3</sub> show the lowest stratospheric mixing ratios originating in the region of Central America and enhanced mixing ratios from Asia (enhancements > 100 % and > 50 %, respectively). However, the source distribution of CHCl<sub>3</sub> is much less clear than that of CH<sub>2</sub>Cl<sub>2</sub> and inconspicuous CH<sub>2</sub>Cl<sub>2</sub> measurements can also contain enhanced CHCl<sub>3</sub> mixing ratios. Nevertheless, the anthropogenic impact on CHCl<sub>3</sub> -rich air from Asia is clearly visible in the measurements and we believe it is likely that a future increase of Asian CHCl<sub>3</sub> emissions could lead to similarly large stratospheric enhancements as already observed for CH<sub>2</sub>Cl<sub>2</sub>. Consequently, this would further increase ozone depletion from stratospheric chlorine deposition of VSLS.</p>

scholarly journals Trace gas composition in the Asian summer monsoon anticyclone: A case study based on aircraft observations and model simulations

2016 ◽  
Author(s):  
Klaus-D. Gottschaldt ◽  
Hans Schlager ◽  
Robert Baumann ◽  
Heiko Bozem ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Atmospheric Chemistry ◽  
Asian Summer Monsoon ◽  
Trace Gas ◽  
Gas Composition ◽  
Back Trajectories ◽  
Air Masses ◽  
Mixing Ratios ◽  
Asian Summer

Abstract. We present in-situ measurements of the trace gas composition of the upper tropospheric (UT) Asian summer monsoon anticyclone (ASMA) performed with the High Altitude and LOng range (HALO) research aircraft in the frame of the Earth System Model Validation (ESMVal) campaign. Air masses with enhanced O3 mixing ratios were encountered after entering the ASMA at its southern edge at about 150 hPa on 18 September 2012. This is in contrast to previous studies, reporting that the anticyclone's interior is dominated by recently uplifted air with low O3 in the monsoon season. We also observed enhanced CO and HCl in the ASMA, tracers for boundary layer pollution and tropopause layer (TL) air or stratospheric inmixing, respectively. In addition, reactive nitrogen was enhanced in the ASMA. Along the HALO flight track across the ASMA boundary, strong gradients of these tracers separate anticyclonic from outside air. Lagrangian trajectory calculations using HYSPLIT show that HALO sampled three times a filament of UT air, which included air masses uplifted from the lower or mid troposphere north of the Bay of Bengal. The trace gas gradients between UT and uplifted air masses were preserved during transport within a belt of streamlines fringing the central part of the anticyclone (fringe), but are smaller than the gradients across the ASMA boundary. Our data represent the first in-situ observations across the southern and downstream the eastern ASMA flank, respectively. Back-trajectories starting at the flight track furthermore indicate that HALO transected the ASMA where it was just splitting into a Tibetan and an Iranian part. The O3-rich filament is diverted from the fringe towards the interior of the original anticyclone, and at least partially bound to become part of the new Iranian eddy. A simulation with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model is found to reproduce the observations reasonably well. It shows that O3-rich air is entrained by the outer streamlines of the anticyclone at its eastern flank. Back-trajectories and increased HCl mixing ratios indicate that the entrained air originates in the stratospherically influenced TL. Photochemical ageing of air masses in the ASMA additionally increases O3 in originally O3-poor, but CO-rich air. Simulated monthly mean trace gas distributions show decreased O3 in the ASMA centre not in general, but only at the 100 hPa level in July and August, as also reported by previous studies. However, at lower altitudes and in September the ASMA is dominated by increased O3, indicating that the above processes are more important for the ASMA trace gas budgets than previously thought.

scholarly journals Efficient transport of tropospheric aerosol into the stratosphere via the Asian summer monsoon anticyclone

2017 ◽  
Vol 114 (27) ◽  
pp. 6972-6977 ◽  
Author(s):  
Pengfei Yu ◽  
Karen H. Rosenlof ◽  
Shang Liu ◽  
Hagen Telg ◽  
Troy D. Thornberry ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Lower Stratosphere ◽  
Model Simulation ◽  
Asian Summer Monsoon ◽  
Volcanic Eruptions ◽  
Aerosol Layer ◽  
Upper Troposphere ◽  
Tropospheric Aerosol ◽  
Asian Summer

An enhanced aerosol layer near the tropopause over Asia during the June–September period of the Asian summer monsoon (ASM) was recently identified using satellite observations. Its sources and climate impact are presently not well-characterized. To improve understanding of this phenomenon, we made in situ aerosol measurements during summer 2015 from Kunming, China, then followed with a modeling study to assess the global significance. The in situ measurements revealed a robust enhancement in aerosol concentration that extended up to 2 km above the tropopause. A climate model simulation demonstrates that the abundant anthropogenic aerosol precursor emissions from Asia coupled with rapid vertical transport associated with monsoon convection leads to significant particle formation in the upper troposphere within the ASM anticyclone. These particles subsequently spread throughout the entire Northern Hemispheric (NH) lower stratosphere and contribute significantly (∼15%) to the NH stratospheric column aerosol surface area on an annual basis. This contribution is comparable to that from the sum of small volcanic eruptions in the period between 2000 and 2015. Although the ASM contribution is smaller than that from tropical upwelling (∼35%), we find that this region is about three times as efficient per unit area and time in populating the NH stratosphere with aerosol. With a substantial amount of organic and sulfur emissions in Asia, the ASM anticyclone serves as an efficient smokestack venting aerosols to the upper troposphere and lower stratosphere. As economic growth continues in Asia, the relative importance of Asian emissions to stratospheric aerosol is likely to increase.

scholarly journals Trace gas composition in the Asian summer monsoon anticyclone: a case study based on aircraft observations and model simulations

2017 ◽  
Vol 17 (9) ◽  
pp. 6091-6111 ◽  
Author(s):  
Klaus-D. Gottschaldt ◽  
Hans Schlager ◽  
Robert Baumann ◽  
Heiko Bozem ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Trace Gas ◽  
Gas Composition ◽  
Back Trajectories ◽  
Air Masses ◽  
Mixing Ratios ◽  
Asian Summer ◽  
In Situ Observations

Abstract. We present in situ measurements of the trace gas composition of the upper tropospheric (UT) Asian summer monsoon anticyclone (ASMA) performed with the High Altitude and Long Range Research Aircraft (HALO) in the frame of the Earth System Model Validation (ESMVal) campaign. Air masses with enhanced O3 mixing ratios were encountered after entering the ASMA at its southern edge at about 150 hPa on 18 September 2012. This is in contrast to the presumption that the anticyclone's interior is dominated by recently uplifted air with low O3 in the monsoon season. We also observed enhanced CO and HCl in the ASMA, which are tracers for boundary layer pollution and tropopause layer (TL) air or stratospheric in-mixing respectively. In addition, reactive nitrogen was enhanced in the ASMA. Along the HALO flight track across the ASMA boundary, strong gradients of these tracers separate anticyclonic from outside air. Lagrangian trajectory calculations using HYSPLIT show that HALO sampled a filament of UT air three times, which included air masses uplifted from the lower or mid-troposphere north of the Bay of Bengal. The trace gas gradients between UT and uplifted air masses were preserved during transport within a belt of streamlines fringing the central part of the anticyclone (fringe), but are smaller than the gradients across the ASMA boundary. Our data represent the first in situ observations across the southern part and downstream of the eastern ASMA flank. Back-trajectories starting at the flight track furthermore indicate that HALO transected the ASMA where it was just splitting into a Tibetan and an Iranian part. The O3-rich filament is diverted from the fringe towards the interior of the original anticyclone, and is at least partially bound to become part of the new Iranian eddy. A simulation with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model is found to reproduce the observations reasonably well. It shows that O3-rich air is entrained by the outer streamlines of the anticyclone at its eastern flank. Back-trajectories and increased HCl mixing ratios indicate that the entrained air originates in the stratospherically influenced TL. Photochemical ageing of air masses in the ASMA additionally increases O3 in originally O3-poor, but CO-rich air. Simulated monthly mean trace gas distributions show decreased O3 in the ASMA centre only at the 100 hPa level in July and August, but at lower altitudes and in September the ASMA is dominated by increased O3. The combination of entrainment from the tropopause region, photochemistry and dynamical instabilities can explain the in situ observations, and might have a larger impact on the highly variable trace gas composition of the anticyclone than previously thought.

scholarly journals A Case Study of Mass Transport during the East-West Oscillation of the Asian Summer Monsoon Anticyclone

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jiali Luo ◽  
Jiayao Song ◽  
Hongying Tian ◽  
Lei Liu ◽  
Xinlei Liang
Keyword(s):  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Chemical Transport ◽  
Upward Motion ◽  
High Concentration ◽  
Upper Troposphere ◽  
Asian Summer ◽  
Mode Tm ◽  
East West

We use ERA-Interim reanalysis, MLS observations, and a trajectory model to examine the chemical transport and tracers distribution in the Upper Troposphere and Lower Stratosphere (UTLS) associated with an east-west oscillation case of the anticyclone in 2016. The results show that the spatial distribution of water vapor (H2O) was more consistent with the location of the anticyclone than carbon monoxide (CO) at 100 hPa, and an independent relative high concentration center was only found in H2O field. At 215 hPa, although the anticyclone center also migrated from the Tibetan Mode (TM) to the Iranian Mode (IM), the relative high concentration centers of both tracers were always colocated with regions where upward motion was strong in the UTLS. When the anticyclone migrated from the TM, air within the anticyclone over Tibetan Plateau may transport both westward and eastward but was always within the UTLS. The relative high concentration of tropospheric tracers within the anticyclone in the IM was from the east and transported by the westward propagation of the anticyclone rather than being lifted from surface directly. Air within the relative high geopotential height centers over Western Pacific was partly from the main anticyclone and partly from lower levels.

scholarly journals In-Situ Chemical and Isotopic Measurements of the Atmosphere of Jupiter

1998 ◽  
Vol 11 (2) ◽  
pp. 1057-1064
Author(s):  
P.R. Mahaffy ◽  
S.K. Atreya ◽  
H.B. Niemann ◽  
T.C. Owen
Keyword(s):  
Mass Spectrometer ◽  
Atmospheric Composition ◽  
Mixing Ratios ◽  
Major Species ◽  
Lateral Mixing ◽  
Detailed Composition ◽  
Different Depths ◽  
Galileo Probe ◽  
Spectrometer Data

AbstractInsights into both the detailed composition of Jupiter’s atmosphere and unexpected local meteorological phenomena were revealed by in-situ measurements from the Galileo Probe Neutral Mass Spectrometer taken on December 7, 1995. Measurements of the neutral atmospheric composition from a pressure of 0.5 bar to approximately 21 bar revealed the mixing ratios of the major species helium and hydrogen as well as numerous minor constituents including methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. This instrument measured the isotope ratios3He/4He, D/H, and13C/12C as well as the isotopes of neon, argon, krypton, and xenon. A summary is given of progress that has been made in refining preliminary estimates of the abundances of condensable volatiles and noble gases as a result of an ongoing laboratory study using a nearly identical engineering unit. The depletion of simple condensable species to depths well below their expected condensation levels is explained by a local downdraft in the region of the probe entry. The mass spectrometer data suggests that different species may recover at different depths and this may be due to lateral mixing of Jovian air.

scholarly journals Characterization of non-methane hydrocarbons in Asian summer monsoon outflow observed by the CARIBIC aircraft

2011 ◽  
Vol 11 (2) ◽  
pp. 503-518 ◽  
Author(s):  
A. K. Baker ◽  
T. J. Schuck ◽  
F. Slemr ◽  
P. van Velthoven ◽  
A. Zahn ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Summer Monsoon ◽  
Fossil Fuels ◽  
Asian Summer Monsoon ◽  
Trace Gases ◽  
Northern Region ◽  
Monsoon Circulation ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Asian Summer

Abstract. Between April and December 2008 the CARIBIC commercial aircraft conducted monthly measurement flights between Frankfurt, Germany and Chennai, India. These flights covered the period of the Asian summer monsoon (June–September), during which enhancements in a number of atmospheric species were observed in the upper troposphere over southwestern Asia. In addition to in situ measurements of trace gases and aerosols, whole air samples were collected during the flights, and these were subsequently analyzed for a suite of trace gases that included a number of C2–C8 non-methane hydrocarbons. Non-methane hydrocarbons are relatively short-lived compounds and the large enhancements in their mixing ratios in the upper troposphere over southwestern Asia during the monsoon, sometimes more than double their spring and fall means, provides qualitative evidence for the influence of convectively uplifted boundary layer air. The particularly large enhancements of the combustion tracers benzene and ethyne, along with the similarity of their ratios with carbon monoxide and emission ratios from the burning of household biofuels, indicate a strong influence of biofuel burning to NMHC emissions in this region. Conversely, the ratios of ethane and propane to carbon monoxide, along with the ratio between i-butane and n-butane, indicate a significant source of these compounds from the use of fossil fuels, and comparison to previous campaigns suggests that this source could be increasing. Photochemical aging patterns of NMHCs showed that the CARIBIC samples were collected in two distinctly different regions of the monsoon circulation: a southern region where air masses had been recently influenced by low level contact and a northern region, where air parcels had spent substantial time in transit in the upper troposphere before being probed. Estimates of age using ratios of individual NMHCs have ranges of 3–6 days in the south and 9–12 days in the north.

scholarly journals Intercomparison of midlatitude tropospheric and lower-stratospheric water vapor measurements and comparison to ECMWF humidity data

2018 ◽  
Vol 18 (22) ◽  
pp. 16729-16745 ◽  
Author(s):  
Stefan Kaufmann ◽  
Christiane Voigt ◽  
Romy Heller ◽  
Tina Jurkat-Witschas ◽  
Martina Krämer ◽  
...  
Keyword(s):  
Water Vapor ◽  
Climate Impact ◽  
Cloud Formation ◽  
Mean Values ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
Quality Of Water ◽  
Research Aircraft ◽  
German Aerospace

Abstract. Accurate measurement of water vapor in the climate-sensitive region near the tropopause is very challenging. Unexplained systematic discrepancies between measurements at low water vapor mixing ratios made by different instruments on airborne platforms have limited our ability to adequately address a number of relevant scientific questions on the humidity distribution, cloud formation and climate impact in that region. Therefore, during the past decade, the scientific community has undertaken substantial efforts to understand these discrepancies and improve the quality of water vapor measurements. This study presents a comprehensive intercomparison of airborne state-of-the-art in situ hygrometers deployed on board the DLR (German Aerospace Center) research aircraft HALO (High Altitude and LOng Range Research Aircraft) during the Midlatitude CIRRUS (ML-CIRRUS) campaign conducted in 2014 over central Europe. The instrument intercomparison shows that the hygrometer measurements agree within their combined accuracy (±10 % to 15 %, depending on the humidity regime); total mean values agree within 2.5 %. However, systematic differences on the order of 10 % and up to a maximum of 15 % are found for mixing ratios below 10 parts per million (ppm) H2O. A comparison of relative humidity within cirrus clouds does not indicate a systematic instrument bias in either water vapor or temperature measurements in the upper troposphere. Furthermore, in situ measurements are compared to model data from the European Centre for Medium-Range Weather Forecasts (ECMWF) which are interpolated along the ML-CIRRUS flight tracks. We find a mean agreement within ±10 % throughout the troposphere and a significant wet bias in the model on the order of 100 % to 150 % in the stratosphere close to the tropopause. Consistent with previous studies, this analysis indicates that the model deficit is mainly caused by too weak of a humidity gradient at the tropopause.

scholarly journals Observations of PAN and its confinement in the Asian summer monsoon anticyclone in high spatial resolution

2016 ◽  
Vol 16 (13) ◽  
pp. 8389-8403 ◽  
Author(s):  
Jörn Ungermann ◽  
Mandfred Ern ◽  
Martin Kaufmann ◽  
Rolf Müller ◽  
Reinhold Spang ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Potential Temperature ◽  
Low Earth Orbit ◽  
Transport Pathway ◽  
Air Masses ◽  
Mixing Ratios ◽  
Asian Summer ◽  
The Relationship ◽  
Eddy Shedding

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.

scholarly journals Global Extratropical Response to Diabatic Heating Variability of the Asian Summer Monsoon

2009 ◽  
Vol 66 (9) ◽  
pp. 2697-2713 ◽  
Author(s):  
Hai Lin
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Convective Activity ◽  
Mean Flow ◽  
Asian Summer ◽  
Circulation Anomalies

Abstract Global teleconnections associated with the Asian summer monsoon convective activities are investigated based on monthly data of 29 Northern Hemisphere summers defined as June–September (JJAS). Two distinct teleconnection patterns are identified that are associated respectively with variabilities of the Indian summer monsoon and the western North Pacific summer monsoon. The Indian summer monsoon convective activity is associated with a global pattern that has a far-reaching connection in both hemispheres, whereas the western North Pacific summer monsoon convective activity is connected to a Southern Hemisphere wave train that influences the high-latitude South Pacific and South America. A global primitive equation model is utilized to assess the cause of the global circulation anomalies. The model responses to anomalous heatings of both monsoon systems match the general features of the observed circulation anomalies well, and they are mainly controlled by linear processes. The response patterns are largely determined by the summertime large-scale background mean flow and the location of the heating anomaly relative to the upper easterly jet in the monsoon region.

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