INTRUSION OF RECENT AIR IN POLAR STRATOSPHERE DURING SUMMER 2009 REVEALED BY BALLOON-BORNE IN SITU CO MEASUREMENTS

International audienceThe SPIRALE (Spectroscopie Infa-Rouge par Absorption de Lasers Embarqués) balloon-borne instrument has been launched twice within 17 days in the polar region (Kiruna, Sweden, 67.9°N-21.1°E) during summer, at the beginning and at the end of August 2009. In situ measurements of several trace gases have been performed including CO and O 3 between 10 and 34 km height, with very high vertical resolution (~5 m). The both flight results are compared and the CO stratospheric profile of the first flight presents specific structures associated with mid-latitude intrusion in the lowest stratospheric levels. Their interpretation is made with the help of results from several modeling tools (MIMOSA and FLEXTRA) and available satellite data (IASI). We also used the O 3 profile correlated with CO to calculate the proportion of recent air in the polar stratosphere. The results indicate the impact of East Asia urban pollution on the chemistry of polar stratosphere in summer

Evidence of convective transport in tropical West Pacific region during SHIVA experiment

Air masses in the convective outflows of four large convective systems near Borneo Island in Malaysia were sampled in the height range 11–13 km within the frame of the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) FP7 European project in November and December 2011. Correlated enhancements of CO, CH4 and the short-lived halogen species (CH3I and CHBr3) were detected when the aircraft crossed the anvils of the four systems. These enhancements were interpreted as the fingerprint of vertical transport from the boundary layer by the convective updraft and then horizontal advection in the outflow. For the four observations, the fraction f of air from the boundary layer ranged between 15 and 67%, showing the variability in transport efficiency depending on the dynamics of the convective system

Global carbonyl sulfide (OCS) measured by MIPAS/Envisat during 2002–2012

We present a global carbonyl sulfide (OCS) data set covering the period June 2002 to April 2012, derived from FTIR (Fourier transform infrared) limb emission spectra measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the ENVISAT satellite. The vertical resolution is 4–5 km in the height region 6–15 km and 15 at 40 km altitude. The total estimated error amounts to 40–50 pptv between 10 and 20 km and to 120 pptv at 40 km altitude. MIPAS OCS data show no systematic bias with respect to balloon observations, with deviations mostly below ±50 pptv. However, they are systematically higher than the OCS volume mixing ratios of the ACE-FTS instrument on SCISAT, with maximum deviations of up to 100 pptv in the altitude region 13–16 km. The data set of MIPAS OCS exhibits only moderate interannual variations and low interhemispheric differences. Average concentrations at 10 km altitude range from 480 pptv at high latitudes to 500–510 pptv in the tropics and at northern mid-latitudes. Seasonal variations at 10 km altitude amount to up to 35 pptv in the Northern and up to 15 pptv in the Southern Hemisphere. Northern hemispheric OCS abundances at 10 km altitude peak in June in the tropics and around October at high latitudes, while the respective southern hemispheric maxima were observed in July and in November. Global OCS distributions at 250 hPa (∼ 10–11 km) show enhanced values at low latitudes, peaking during boreal summer above the western Pacific and the Indian Ocean, which indicates oceanic release. Further, a region of depleted OCS amounts extending from Brazil to central and southern Africa was detected at this altitude, which is most pronounced in austral summer. This depletion is related to seasonally varying vegetative uptake by the tropical forests. Typical signatures of biomass burning like the southern hemispheric biomass burning plume are not visible in MIPAS data, indicating that this process is only a minor source of upper tropospheric OCS. At the 150 hPa level (∼ 13–14 km) enhanced amounts of OCS were also observed inside the Asian monsoon anticyclone, but this enhancement is not especially outstanding compared to other low latitude regions at the same altitude. At the 80 hPa level (∼ 17–18 km), equatorward transport of mid-latitude air masses containing lower OCS amounts around the summertime anticyclones was observed. A significant trend could not be detected in upper tropospheric MIPAS OCS amounts, which points to globally balanced sources and sinks. Simulations with the ECHAM-MESSy model reproduce the observed latitudinal cross sections fairly well

N2O Temporal Variability from the Middle Troposphere to the Middle Stratosphere Based on Airborne and Balloon-Borne Observations during the Period 1987–2018

Nitrous oxide (N2O) is the fourth most important greenhouse gas in the atmosphere and is considered the most important current source gas emission for global stratospheric ozone depletion (O3 ). It has natural and anthropogenic sources, mainly as an unintended by-product of food production activities. This work examines the identification and quantification of trends in the N2O concentration from the middle troposphere to the middle stratosphere (MTMS) by in situ and remote sensing observations. The temporal variability of N2O is addressed using a comprehensive dataset of in situ and remote sensing N2O concentrations based on aircraft and balloon measurements in the MTMS from 1987 to 2018. We determine N2O trends in the MTMS, based on observations. This consistent dataset was also used to study the N2O seasonal cycle to investigate the relationship between abundances and its emission sources through zonal means. The results show a longterm increase in global N2O concentration in the MTMS with an average of 0.89 ± 0.07 ppb/yr in the troposphere and 0.96 ± 0.15 ppb/yr in the stratosphere, consistent with 0.80 ppb/yr derived from ground-based measurements and 0.799 ± 0.024 ppb/yr ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) satellite measurements

N2_2O Temporal Variability from the Middle Troposphere to the Middle Stratosphere Based on Airborne and Balloon-Borne Observations during the Period 1987–2018

Nitrous oxide (N$_2$O) is the fourth most important greenhouse gas in the atmosphere and is considered the most important current source gas emission for global stratospheric ozone depletion (O$_3$). It has natural and anthropogenic sources, mainly as an unintended by-product of food production activities. This work examines the identification and quantification of trends in the N$_2$O concentration from the middle troposphere to the middle stratosphere (MTMS) by in situ and remote sensing observations. The temporal variability of N$_2$O is addressed using a comprehensive dataset of in situ and remote sensing N$_2$O concentrations based on aircraft and balloon measurements in the MTMS from 1987 to 2018. We determine N$_2$O trends in the MTMS, based on observations. This consistent dataset was also used to study the N$_2$O seasonal cycle to investigate the relationship between abundances and its emission sources through zonal means. The results show a long-term increase in global N$_2$O concentration in the MTMS with an average of 0.89 ± 0.07 ppb/yr in the troposphere and 0.96 ± 0.15 ppb/yr in the stratosphere, consistent with 0.80 ppb/yr derived from ground-based measurements and 0.799 ± 0.024 ppb/yr ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) satellite measurements

Transport et chimie d'espèces soufrées et bromées dans la haute troposphère et basse stratosphère diagnostiqués par des mesures sous ballon et en avion et par modélisation

Ozone depletion is a complex subject involving several processes starting by the emission of the sources gases (SGs) in the lower troposphere. Recently the VSLS (very short lived substances) have been identified as potential SGs. However they do not have a lifetime long enough to reach directly the stratosphere. During the transport, the VSLS undergo degradation leading to products gases (PGs). The SGs and PGs of the VSLS reach the stratosphere in the Tropical region where a rapid vertical transport occurs, the convection. The SGs with longer lifetime can reach the stratosphere by any transport pathway from the location of their emissions. Once in stratosphere the SGs and PGs will be converted into reactive species able to deplete ozone. This thesis presents the study of the several steps occurring before the ozone depletion: SGs emission, SGs and PGs transport into the atmosphere, the chemical degradation occurring during their transport and finally their contribution to the ozone depletion. First, chemical tracers, as CO, are used to highlight the main pathways from the troposphere to the stratosphere. Then two studies of two different types of species entering in the process of ozone destruction are presented: for OCS (carbonyl sulfide) and the brominated VSLS (CHBr3 et CH2Br2). OCS is one of the sulfate aerosols precursors catalyzing the ozone depletion. However, OCS contribution to this layer has some uncertainties. OCS emission sources, the latitude repartition and the contribution to the sulfate aerosols are presented. The contribution of the brominated VSLS to the stratospheric bromine is a key issue that being almost resolved. The brominated VSLS chemical degradation during the atmospheric transport will be described in detail.Le phénomène de destruction de l’ozone est un sujet vaste mettant en scène de nombreux processus. Il a pour origine l’émission de composés dits gaz sources (SGs) dans la troposphère. Récemment, les espèces à très courte durée de vie (VSLS) ont été identifiées comme SGs possibles. Cependant, elles ne possèdent pas un temps de vie suffisamment long pour atteindre directement la stratosphère. Les VSLS se dégradent au cours de leur transport, conduisant à des composés intermédiaires, les gaz produits (PGs). Les SGs et les PGs des VSLS vont entrer dans la stratosphère au niveau des régions équatoriales où règne un transport vertical rapide, la convection. Les SGs à temps de vie plus long peuvent accéder à la stratosphère par tous les types de transport possibles. Une fois dans la stratosphère, les SGs et PGs vont être convertis en espèces réactives capables de détruire l’ozone. Cette thèse présente l’étude des différentes étapes se produisant avant la destruction de l’ozone : l’émission et le transport des SGs dans l’atmosphère, leur chimie de dégradation au cours de leur transport et enfin leur contribution à la destruction de l’ozone. Les traceurs chimiques tels que CO sont tout d’abord utilisés pour mettre en évidence le transport des SGs et PGs de la troposphère à la stratosphère. Puis, deux études décrivant 2 types d’espèces différentes, entrant dans le processus de destruction de l’ozone, sont présentées : pour OCS (sulfure de carbonyle) et les VSLS bromés (CHBr3 et CH2Br2). OCS est l’un des principaux précurseurs d’aérosols sulfatés présents dans la stratosphère catalysant la destruction de l’ozone par chimie hétérogène. Cependant, sa contribution à cette couche comporte de nombreuses incertitudes. Ses sources d’émissions, sa répartition avec la latitude et sa contribution à la couche d’aérosols sulfatés sont présentées. La contribution des VSLS bromées au brome de la stratosphère est une question en cours de résolution. Leur chimie au cours de leur transport dans l’atmosphère est décrite de manière détaillée

Transport and chemistry of sulfur and bromine compounds in the upper troposhere and lower stratosphere diagnosed by balloon and aircraft measurements and modelling

Le phénomène de destruction de l’ozone est un sujet vaste mettant en scène de nombreux processus. Il a pour origine l’émission de composés dits gaz sources (SGs) dans la troposphère. Récemment, les espèces à très courte durée de vie (VSLS) ont été identifiées comme SGs possibles. Cependant, elles ne possèdent pas un temps de vie suffisamment long pour atteindre directement la stratosphère. Les VSLS se dégradent au cours de leur transport, conduisant à des composés intermédiaires, les gaz produits (PGs). Les SGs et les PGs des VSLS vont entrer dans la stratosphère au niveau des régions équatoriales où règne un transport vertical rapide, la convection. Les SGs à temps de vie plus long peuvent accéder à la stratosphère par tous les types de transport possibles. Une fois dans la stratosphère, les SGs et PGs vont être convertis en espèces réactives capables de détruire l’ozone. Cette thèse présente l’étude des différentes étapes se produisant avant la destruction de l’ozone : l’émission et le transport des SGs dans l’atmosphère, leur chimie de dégradation au cours de leur transport et enfin leur contribution à la destruction de l’ozone. Les traceurs chimiques tels que CO sont tout d’abord utilisés pour mettre en évidence le transport des SGs et PGs de la troposphère à la stratosphère. Puis, deux études décrivant 2 types d’espèces différentes, entrant dans le processus de destruction de l’ozone, sont présentées : pour OCS (sulfure de carbonyle) et les VSLS bromés (CHBr3 et CH2Br2). OCS est l’un des principaux précurseurs d’aérosols sulfatés présents dans la stratosphère catalysant la destruction de l’ozone par chimie hétérogène. Cependant, sa contribution à cette couche comporte de nombreuses incertitudes. Ses sources d’émissions, sa répartition avec la latitude et sa contribution à la couche d’aérosols sulfatés sont présentées. La contribution des VSLS bromées au brome de la stratosphère est une question en cours de résolution. Leur chimie au cours de leur transport dans l’atmosphère est décrite de manière détaillée.Ozone depletion is a complex subject involving several processes starting by the emission of the sources gases (SGs) in the lower troposphere. Recently the VSLS (very short lived substances) have been identified as potential SGs. However they do not have a lifetime long enough to reach directly the stratosphere. During the transport, the VSLS undergo degradation leading to products gases (PGs). The SGs and PGs of the VSLS reach the stratosphere in the Tropical region where a rapid vertical transport occurs, the convection. The SGs with longer lifetime can reach the stratosphere by any transport pathway from the location of their emissions. Once in stratosphere the SGs and PGs will be converted into reactive species able to deplete ozone. This thesis presents the study of the several steps occurring before the ozone depletion: SGs emission, SGs and PGs transport into the atmosphere, the chemical degradation occurring during their transport and finally their contribution to the ozone depletion. First, chemical tracers, as CO, are used to highlight the main pathways from the troposphere to the stratosphere. Then two studies of two different types of species entering in the process of ozone destruction are presented: for OCS (carbonyl sulfide) and the brominated VSLS (CHBr3 et CH2Br2). OCS is one of the sulfate aerosols precursors catalyzing the ozone depletion. However, OCS contribution to this layer has some uncertainties. OCS emission sources, the latitude repartition and the contribution to the sulfate aerosols are presented. The contribution of the brominated VSLS to the stratospheric bromine is a key issue that being almost resolved. The brominated VSLS chemical degradation during the atmospheric transport will be described in detail

Transport et chimie d'espèces soufrées et bromées dans la haute troposphère et basse stratosphère diagnostiqués par des mesures sous ballon et en avion et par modélisation

Le phénomène de destruction de l ozone est un sujet vaste mettant en scène de nombreux processus. Il a pour origine l émission de composés dits gaz sources (SGs) dans la troposphère. Récemment, les espèces à très courte durée de vie (VSLS) ont été identifiées comme SGs possibles. Cependant, elles ne possèdent pas un temps de vie suffisamment long pour atteindre directement la stratosphère. Les VSLS se dégradent au cours de leur transport, conduisant à des composés intermédiaires, les gaz produits (PGs). Les SGs et les PGs des VSLS vont entrer dans la stratosphère au niveau des régions équatoriales où règne un transport vertical rapide, la convection. Les SGs à temps de vie plus long peuvent accéder à la stratosphère par tous les types de transport possibles. Une fois dans la stratosphère, les SGs et PGs vont être convertis en espèces réactives capables de détruire l ozone. Cette thèse présente l étude des différentes étapes se produisant avant la destruction de l ozone : l émission et le transport des SGs dans l atmosphère, leur chimie de dégradation au cours de leur transport et enfin leur contribution à la destruction de l ozone. Les traceurs chimiques tels que CO sont tout d abord utilisés pour mettre en évidence le transport des SGs et PGs de la troposphère à la stratosphère. Puis, deux études décrivant 2 types d espèces différentes, entrant dans le processus de destruction de l ozone, sont présentées : pour OCS (sulfure de carbonyle) et les VSLS bromés (CHBr3 et CH2Br2). OCS est l un des principaux précurseurs d aérosols sulfatés présents dans la stratosphère catalysant la destruction de l ozone par chimie hétérogène. Cependant, sa contribution à cette couche comporte de nombreuses incertitudes. Ses sources d émissions, sa répartition avec la latitude et sa contribution à la couche d aérosols sulfatés sont présentées. La contribution des VSLS bromées au brome de la stratosphère est une question en cours de résolution. Leur chimie au cours de leur transport dans l atmosphère est décrite de manière détaillée.Ozone depletion is a complex subject involving several processes starting by the emission of the sources gases (SGs) in the lower troposphere. Recently the VSLS (very short lived substances) have been identified as potential SGs. However they do not have a lifetime long enough to reach directly the stratosphere. During the transport, the VSLS undergo degradation leading to products gases (PGs). The SGs and PGs of the VSLS reach the stratosphere in the Tropical region where a rapid vertical transport occurs, the convection. The SGs with longer lifetime can reach the stratosphere by any transport pathway from the location of their emissions. Once in stratosphere the SGs and PGs will be converted into reactive species able to deplete ozone. This thesis presents the study of the several steps occurring before the ozone depletion: SGs emission, SGs and PGs transport into the atmosphere, the chemical degradation occurring during their transport and finally their contribution to the ozone depletion. First, chemical tracers, as CO, are used to highlight the main pathways from the troposphere to the stratosphere. Then two studies of two different types of species entering in the process of ozone destruction are presented: for OCS (carbonyl sulfide) and the brominated VSLS (CHBr3 et CH2Br2). OCS is one of the sulfate aerosols precursors catalyzing the ozone depletion. However, OCS contribution to this layer has some uncertainties. OCS emission sources, the latitude repartition and the contribution to the sulfate aerosols are presented. The contribution of the brominated VSLS to the stratospheric bromine is a key issue that being almost resolved. The brominated VSLS chemical degradation during the atmospheric transport will be described in detail.ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF

N2O temporal variability from the middle troposphere to the middle stratosphere based on airborne and balloon-borne observations during the period 1987-2018

International audienceNitrous oxide (N2O) is the third most important greenhouse gas in the atmosphere and is now considered as the most important depleting source gas of stratospheric ozone (O3). Its sources are both natural and anthropogenic, mainly as an unintended by-product of human food production activities. Scientifically, a major issue is the identification and quantification of trends in the N2O concentration from the middle troposphere to the middle stratosphere (MTMS) by in-situ and remote sensing observations due to the paucity of measurements. To address the temporal variability of N2O, we assembled the first comprehensive dataset for in-situ and remote sensing N2O concentrations from 1987 to 2018, based on aircraft and balloon measurements in the MTMS. Using statistical methods, we quality-controlled all the measurements to exclude outliers and particular dynamic cases (tropospheric intrusion, stratospheric descent). This allowed us to determine N2O trends in the MTMS, based on selected observations during the period 1987-2018. This consistent dataset was also used to study the N2O seasonal cycle in order to investigate the relationship with its emission sources through zonal means and atmospheric dynamic. The results show a long-term (30 years) increase in global N2O concentration in the MTMS with an average of 0.89 ± 0.09 ppb/yr in the troposphere and 0.95 ± 0.13 ppb/yr in the stratosphere, consistent with 0.80 ppb/yr derived from ground measurements and ACE-FTS satellite measurements

An airborne spectrometer with three infrared lasers for trace gas measurements applied to convection case studies

International audienceAn infrared absorption spectrometer named SPIRIT (SPectromètre InfraRouge In situ Toute altitude) has been built for airborne simultaneous online measurements of trace gases. SPIRIT is based on two recent technological advances, leading to optimal performances and miniaturization: continuous wave quantum cascade lasers (CW-QCL) operating near room temperature coupled to a new, patented, multipass optical cell (Robert, Appl. Optics, 2007). An essential electronic development allows the sequential use of three QCLs with the same single cell. With judicious selected spectral micro-windows, this potentially leads to the measurements of at least four species at 0.7 Hz frequency. The first deployment of SPIRIT was made onboard the DLR Falcon-20 aircraft during the campaign associated to the EU SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project in Nov.-Dec. 2011 over Malaysia. In the present paper, the flight of 19 Nov. is presented in detail as an example of the SPIRIT performances, with CO, CO2, CH4 and N2O as measured species. The aircraft crossed four times the anvil of a severe thunderstorm from 11.3 km to 12.8 km altitude corresponding to a large convective system near Borneo island (6.0 °N-115.5 °E). During the crossing, carbon monoxide mixing ratios increase by 5 to 10 ppbv from the ambient cloud free environment to the anvil cloud correlated with an increase of CH4 mixing ratio. Using these observations, the fraction of boundary layer air contained in fresh convective outflow has been calculated. Other convection cases were detected, allowing for other fractions to be calculated, with results ranging between 0.15 and 0.55 and showing the variability of the mixing taking place during convective transport