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

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

Etude de la dynamique de la moyenne atmosphère de Mars à partir de données millimètriques

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Cementite Residual Stress Analysis in Gas-nitrided Low Alloy Steels

This paper deals with the measurement of residual stresses in cementite after gas-nitriding of a 33CrMoV12-9 steel. During nitriding, precipitation of nanometric alloying elements nitrides and cementite at grain boundaries occurs leading to an increase of superficial hardness and providing compressive residual stresses in the surface layer. The stress state in the ferritic matrix has generally been measured to characterize the mechanical behaviour of the nitrided case while the other phases are not taken into account. In order to better understand the mechanical behaviour (e.g. fatigue life and localization of cracks initiation) of heterogeneous material such as in case of nitrided surfaces, the nature (sign, level) of residual stresses (or pseudo-macro-stresses) of the present phases can be calculated from measurements using X-ray diffraction to select the considered phase. Due to a low volume fraction of cementite through a nitrided case, an approach based on X-ray and electron backscattered diffractions (XRD and EBSD respectively) is proposed to perform stress measurements in cementite. An optimization of the surface preparation (by mechanical and/or chemical polishing techniques) prior to EBSD analysis was performed in order to minimize deformation induced by surface preparation. Pseudo-macro-stresses were calculated in tempered martensite and cementite. Results are compared to local residual stress measurements carried out by a cross-correlation method using EBSD patterns

Volcanic Halogens Processing and Impacts in the Troposphere and Stratosphere

International audienceVolcanoes release vast quantities of gases, including halogens (e.g. HBr, HCl) as well as sulfur (SO2). Volcanic SO2 is oxidized into sulfate aerosols in the atmosphere that impact climate and favor the destruction of stratospheric ozone. Volcanic halogen emissions can also be oxidized in the plume to form reactive halogens (including BrO, OClO). The near-source plume processing is an important control on whether volcanic halogens become activated to destroy tropospheric ozone (Roberts, Geosciences, 2018). In addition, satellite observations show that volcanic halogens (e.g. HCl) can be co-injected with SO2 into the stratosphere, with potential for further chemistry-climate impacts. Building on earlier box and 1D model studies we have performed 3D regional and global atmospheric model investigations of the processing and atmospheric impacts from volcanic halogens released from present-day degassing/eruption case studies. In the troposphere: Jourdain et al. ACP (2016) simulate the local-regional scale processing of a large continuous release of halogens and sulfur from Ambrym volcano in 2005. The model predicts conversion of emitted HBr into reactive bromine species (BrO, HOBr, Br, Br2, BrCl, BrONO2) downwind from the volcano, reproducing reported measurements of plume BrO. As well as predicting a strong depletion of tropospheric ozone regionally, the study highlights the potential for volcanic reactive halogens to be convectively transported into the stratosphere. In the stratosphere: Lurton et al. ACP (2018) simulate the chemical processing and aerosol microphysics following the injection of volcanic SO2 and HCl by the 2009 Sarychev Peak eruption, using a global earth system model. Stratospheric ozone depletion is more severe by about forty percent in the model simulation that includes the HCl co-injection than for the SO2-only case. Both models identify effects of coupled SO2-halogens processing: volcanic halogen chemistry depletes oxidants (ozone, HOx, NOx) and consequently slows the oxidation of SO2 into sulfate aerosols, whilst volcanic sulfate aerosols have a key role in the multi-phase processing of volcanic halogens. Understanding this synergy is crucial to quantifying the impacts of volcanic halogen-sulfur emissions in the present day and also from past volcanic events

Volcanic Halogens Processing and Impacts in the Troposphere and Stratosphere

International audienceVolcanoes release vast quantities of gases, including halogens (e.g. HBr, HCl) as well as sulfur (SO2). Volcanic SO2 is oxidized into sulfate aerosols in the atmosphere that impact climate and favor the destruction of stratospheric ozone. Volcanic halogen emissions can also be oxidized in the plume to form reactive halogens (including BrO, OClO). The near-source plume processing is an important control on whether volcanic halogens become activated to destroy tropospheric ozone (Roberts, Geosciences, 2018). In addition, satellite observations show that volcanic halogens (e.g. HCl) can be co-injected with SO2 into the stratosphere, with potential for further chemistry-climate impacts. Building on earlier box and 1D model studies we have performed 3D regional and global atmospheric model investigations of the processing and atmospheric impacts from volcanic halogens released from present-day degassing/eruption case studies. In the troposphere: Jourdain et al. ACP (2016) simulate the local-regional scale processing of a large continuous release of halogens and sulfur from Ambrym volcano in 2005. The model predicts conversion of emitted HBr into reactive bromine species (BrO, HOBr, Br, Br2, BrCl, BrONO2) downwind from the volcano, reproducing reported measurements of plume BrO. As well as predicting a strong depletion of tropospheric ozone regionally, the study highlights the potential for volcanic reactive halogens to be convectively transported into the stratosphere. In the stratosphere: Lurton et al. ACP (2018) simulate the chemical processing and aerosol microphysics following the injection of volcanic SO2 and HCl by the 2009 Sarychev Peak eruption, using a global earth system model. Stratospheric ozone depletion is more severe by about forty percent in the model simulation that includes the HCl co-injection than for the SO2-only case. Both models identify effects of coupled SO2-halogens processing: volcanic halogen chemistry depletes oxidants (ozone, HOx, NOx) and consequently slows the oxidation of SO2 into sulfate aerosols, whilst volcanic sulfate aerosols have a key role in the multi-phase processing of volcanic halogens. Understanding this synergy is crucial to quantifying the impacts of volcanic halogen-sulfur emissions in the present day and also from past volcanic events

Volcanic Halogens Processing and Impacts in the Troposphere and Stratosphere

International audienceVolcanoes release vast quantities of gases, including halogens (e.g. HBr, HCl) as well as sulfur (SO2). Volcanic SO2 is oxidized into sulfate aerosols in the atmosphere that impact climate and favor the destruction of stratospheric ozone. Volcanic halogen emissions can also be oxidized in the plume to form reactive halogens (including BrO, OClO). The near-source plume processing is an important control on whether volcanic halogens become activated to destroy tropospheric ozone (Roberts, Geosciences, 2018). In addition, satellite observations show that volcanic halogens (e.g. HCl) can be co-injected with SO2 into the stratosphere, with potential for further chemistry-climate impacts. Building on earlier box and 1D model studies we have performed 3D regional and global atmospheric model investigations of the processing and atmospheric impacts from volcanic halogens released from present-day degassing/eruption case studies. In the troposphere: Jourdain et al. ACP (2016) simulate the local-regional scale processing of a large continuous release of halogens and sulfur from Ambrym volcano in 2005. The model predicts conversion of emitted HBr into reactive bromine species (BrO, HOBr, Br, Br2, BrCl, BrONO2) downwind from the volcano, reproducing reported measurements of plume BrO. As well as predicting a strong depletion of tropospheric ozone regionally, the study highlights the potential for volcanic reactive halogens to be convectively transported into the stratosphere. In the stratosphere: Lurton et al. ACP (2018) simulate the chemical processing and aerosol microphysics following the injection of volcanic SO2 and HCl by the 2009 Sarychev Peak eruption, using a global earth system model. Stratospheric ozone depletion is more severe by about forty percent in the model simulation that includes the HCl co-injection than for the SO2-only case. Both models identify effects of coupled SO2-halogens processing: volcanic halogen chemistry depletes oxidants (ozone, HOx, NOx) and consequently slows the oxidation of SO2 into sulfate aerosols, whilst volcanic sulfate aerosols have a key role in the multi-phase processing of volcanic halogens. Understanding this synergy is crucial to quantifying the impacts of volcanic halogen-sulfur emissions in the present day and also from past volcanic events

Volcanic Halogens Processing and Impacts in the Troposphere and Stratosphere

International audienceVolcanoes release vast quantities of gases, including halogens (e.g. HBr, HCl) as well as sulfur (SO2). Volcanic SO2 is oxidized into sulfate aerosols in the atmosphere that impact climate and favor the destruction of stratospheric ozone. Volcanic halogen emissions can also be oxidized in the plume to form reactive halogens (including BrO, OClO). The near-source plume processing is an important control on whether volcanic halogens become activated to destroy tropospheric ozone (Roberts, Geosciences, 2018). In addition, satellite observations show that volcanic halogens (e.g. HCl) can be co-injected with SO2 into the stratosphere, with potential for further chemistry-climate impacts. Building on earlier box and 1D model studies we have performed 3D regional and global atmospheric model investigations of the processing and atmospheric impacts from volcanic halogens released from present-day degassing/eruption case studies. In the troposphere: Jourdain et al. ACP (2016) simulate the local-regional scale processing of a large continuous release of halogens and sulfur from Ambrym volcano in 2005. The model predicts conversion of emitted HBr into reactive bromine species (BrO, HOBr, Br, Br2, BrCl, BrONO2) downwind from the volcano, reproducing reported measurements of plume BrO. As well as predicting a strong depletion of tropospheric ozone regionally, the study highlights the potential for volcanic reactive halogens to be convectively transported into the stratosphere. In the stratosphere: Lurton et al. ACP (2018) simulate the chemical processing and aerosol microphysics following the injection of volcanic SO2 and HCl by the 2009 Sarychev Peak eruption, using a global earth system model. Stratospheric ozone depletion is more severe by about forty percent in the model simulation that includes the HCl co-injection than for the SO2-only case. Both models identify effects of coupled SO2-halogens processing: volcanic halogen chemistry depletes oxidants (ozone, HOx, NOx) and consequently slows the oxidation of SO2 into sulfate aerosols, whilst volcanic sulfate aerosols have a key role in the multi-phase processing of volcanic halogens. Understanding this synergy is crucial to quantifying the impacts of volcanic halogen-sulfur emissions in the present day and also from past volcanic events

Volcanic Halogens Processing and Impacts in the Troposphere and Stratosphere

International audienceVolcanoes release vast quantities of gases, including halogens (e.g. HBr, HCl) as well as sulfur (SO2). Volcanic SO2 is oxidized into sulfate aerosols in the atmosphere that impact climate and favor the destruction of stratospheric ozone. Volcanic halogen emissions can also be oxidized in the plume to form reactive halogens (including BrO, OClO). The near-source plume processing is an important control on whether volcanic halogens become activated to destroy tropospheric ozone (Roberts, Geosciences, 2018). In addition, satellite observations show that volcanic halogens (e.g. HCl) can be co-injected with SO2 into the stratosphere, with potential for further chemistry-climate impacts. Building on earlier box and 1D model studies we have performed 3D regional and global atmospheric model investigations of the processing and atmospheric impacts from volcanic halogens released from present-day degassing/eruption case studies. In the troposphere: Jourdain et al. ACP (2016) simulate the local-regional scale processing of a large continuous release of halogens and sulfur from Ambrym volcano in 2005. The model predicts conversion of emitted HBr into reactive bromine species (BrO, HOBr, Br, Br2, BrCl, BrONO2) downwind from the volcano, reproducing reported measurements of plume BrO. As well as predicting a strong depletion of tropospheric ozone regionally, the study highlights the potential for volcanic reactive halogens to be convectively transported into the stratosphere. In the stratosphere: Lurton et al. ACP (2018) simulate the chemical processing and aerosol microphysics following the injection of volcanic SO2 and HCl by the 2009 Sarychev Peak eruption, using a global earth system model. Stratospheric ozone depletion is more severe by about forty percent in the model simulation that includes the HCl co-injection than for the SO2-only case. Both models identify effects of coupled SO2-halogens processing: volcanic halogen chemistry depletes oxidants (ozone, HOx, NOx) and consequently slows the oxidation of SO2 into sulfate aerosols, whilst volcanic sulfate aerosols have a key role in the multi-phase processing of volcanic halogens. Understanding this synergy is crucial to quantifying the impacts of volcanic halogen-sulfur emissions in the present day and also from past volcanic events