VolKilau: Volcano rapid response balloon campaign during the 2018 Kilauea eruption

After nearly 35 years of stable activity, the Kilauea volcanic system in Hawaii went through sudden changes in May 2018 with the emergence of 20 volcanic fissures along the Lower Eastern Rift Zone (LERZ), destroying 700 homes in Leilani Estates and forcing more than 2,000 people to evacuate. Elevated volcanic emissions lasted for several months between May and September 2018, leading to low visibility and poor air quality in Hawaii and across the western Pacific. The NASA-funded VolKilau mission was rapidly mounted and conducted between 11 and 18 June 2018 to (i) profile volcanic emissions with SO2 and aerosol measurements, (ii) validate satellite observations, and (iii) increase readiness for the next large volcanic eruption. Through a series of balloon-borne measurements with tethered and free-released launches, we measured SO2 concentration, aerosol concentration, and optical properties 60–80 km downwind from the volcanic fissures using gas sensors, optical particle counters, backscatter sondes, and an aerosol impactor. While most of the measurements made during the Kilauea eruption were ground based, the VolKilau mission represented a unique opportunity to characterize plume properties, constrain emission profiles, study early chemistry involving the conversion of SO2 into sulfuric acid, and understand the influence of water clouds in the removal of SO2. This unprecedented combination of measurements has significantly improved our team’s ability to assess the atmospheric and human impacts of a major event such as this

Une étude approfondie de la composition des aérosols stratosphériques par ballons : aperçu des émissions asiatiques, des éruptions volcaniques et des incendies de forêt

Atmospheric aerosols have a significant impact on the physics and chemistry of the atmosphere by inter-acting with solar and IR radiations and by participating in multiple chemical reactions. They also playa crucial role as nuclei for cloud droplet and ice crystal formation. Understanding the characteristics ofaerosol optical, physical, and chemical properties provides insights into their origin, history, and potential implications for the environment and human health. The stratosphere, an important component of Earth’s climate system, has undergone notable changes due to atmospheric pollution, ozone depletion and circulation alterations, posing research challenges. This Ph.D. thesis analyzes the effects of volcanic eruptions, anthropogenic emissions in Asia, and wildfire emissions on the chemical composition of the stratospheric aerosol layer, specifically focusing on the alterations in aerosol population during three field campaigns: BATAL, BraVo, and REAS. Balloon-borne aerosol collectors, optical particle counters, andother instruments were used to explore the chemical, physical, and optical properties of different aerosollayers. The results were compared with satellite data to illuminate the source and evolution. The analysis of air masses and model simulations provided insights into the transport and distribution of these aerosols.Les aérosols atmosphériques ont un impact significatif sur la physique et la chimie de l’atmosphère en interagissant avec les rayonnements solaires et IR et en participant à de multiples réactions chimiques.Ils jouent également un rôle crucial en tant que noyaux pour la formation de gouttelettes de nuages et de cristaux de glace. Les aérosols d’origine humaine ont un effet de refroidissement qui contraste avec l’effet de réchauffement des gaz à effet de serre, comme le souligne le rapport du GIEC de 2013. Caractériser les propriétés optiques, microphysiques et chimiques des aérosols permet de mieux comprendre leur origine,leur histoire et leurs implications potentielles pour l’environnement et la santé humaine. La stratosphère,une composante importante du système climatique de la Terre, a subi des changements notables en raison de la pollution atmosphérique, de l’appauvrissement de la couche d’ozone et des altérations de la circulation, ce qui pose des défis à la recherche. Cette thèse analyse les effets des éruptions volcaniques,des émissions anthropiques en Asie et des émissions de feux de forêt sur la composition chimique de la couche d’aérosols stratosphériques, en se concentrant spécifiquement sur les impacts sur la population d’aérosols au cours de trois campagnes de terrain : BATAL, Bravo et REAS. Des collecteurs d’aérosols embarqués sous ballons, des compteurs optiques de particules et d’autres instruments ont été utilisés pour explorer les propriétés chimiques, microphysiques et optiques de différentes couches d’aérosols. Les résultats ont été comparés aux données satellitaires afin de faire la lumière sur les sources des aérosols et leur mécanisme d’évolution. L’analyse des masses d’air et les simulations de modèles ont permis de mieux comprendre le transport et la distribution de ces aérosols

Balloon-borne sample analysis of organic compounds present across atmospheric layers ranging from the troposphere to lower stratosphere

International audienceAtmospheric aerosols play an important role in the Earth’s climate system. We present the analysis of atmospheric molecules/particles collected with a sampling system that can fly under regular weather balloons. The flights took place on 10 October 2022 from Reims and on 13 December 2022 from Orléans (France). The samples collected on activated carbon filters were analyzed by high-resolution mass spectrometry (Orbitrap Q-Exactive). Using Desorption electrospray ionization (DESI), we could derive hundreds of chemical formulas for organic species present in different layers from the troposphere to the stratosphere (up to 20 km). Measurements of O3, CO, and aerosol concentrations a few hours before these flights took place to contextualize the sampling. Chemical analysis of samples taken at different altitudes shows, in addition to a common set of chemical compounds, significant differences in the number and size of organic species detected. This finding must reflect the unique composition of the atmospheric layers, but also a common pattern of organic compounds. In the tropospheric samples, we found significant oxidised and saturated components, with carbon numbers below 30, which could be explained by complex organic chemistry originating from local and distant emission sources. In samples from the upper troposphere and stratosphere, we detected chemical formulae with higher carbon numbers (C>30). Significantly lower unsaturation numbers were observed in the compounds collected in the stratosphere, which could be the result of UV radiation.The multimodal distributions of carbon numbers in chemical formulas observed between 15-20 km suggest that oligomerization and growth of organic molecules may take place in aged air masses of tropical origin that are known to carry organic compounds even several km above the tropopause where their lifetime significantly increases. Overall, these results are consistent with the injection of fire smoke months before the in-situ observations and with thermodynamics inherent to conditions prevailing in the stratosphere This new analysis method meets the requirements of balloon flights in terms of flexibility and cost

The first balloon-borne sample analysis of atmospheric carbonaceous components reveals new insights into formation processes

International audienceAtmospheric aerosol optical, physical, and chemical properties play a fundamental role in the Earth’s climate system. A better understanding of the processes involved in their formation, evolution, and interaction with radiation and the water cycle is critical. We report the analysis of atmospheric molecules/particles collected with a new sampling system that flew under regular weather balloons for the first time. The flight took place on 18/01/2022 from Reims (France). The samples were subsequently analyzed by high-resolution mass spectrometry (Orbitrap) to specifically infer hundreds of organic components present in 4 different layers from the troposphere to the stratosphere (up to 20 km). Additional measurements of O3, CO, and aerosol concentrations a few hours before this flight took place to contextualize the sampling. After separating common species found on each filter that might be common to atmospheric layers or residuals for contaminations, we found that each sample yields significant differences in the number and size of organic species detected that should reflect the unique composition of atmospheric layers. While tropospheric samples yield significantly oxidized and saturated components, with carbon numbers below 30 that might be explained by complex organics chemistry from local and distant source emissions, the upper tropospheric and stratospheric samples were associated with increased carbon numbers (C>30), with a significantly reduced unsaturation number for the stratosphere, that might be induced by strong UV radiations. The multimodal distributions of carbon numbers in chemical formulas observed between 15-20 km suggest that oligomerization and growth of organic molecules may take place in aged air masses of tropical origin that are known to carry organic compounds even several km above the tropopause where their lifetime significantly increases. In addition, the presence of organics may also reflect the extended influence of wildfires smoke injected during the spring and summer in the NH hemisphere before the in situ observations and their long-lifetime in the upper troposphere and stratosphere

Exploring the inorganic composition of the Asian Tropopause Aerosol Layer using medium-duration balloon flights

International audienceSatellite observations have revealed an enhanced aerosol layer near the tropopause over Asia during the summer monsoon, called the "Asian Tropopause Aerosol Layer" (ATAL). In this work, aerosol particles in the ATAL were collected with a balloon-borne impactor near the tropopause region over India, using extended-duration balloon flights, in summer 2017 and winter 2018. The chemical composition of these particles was further investigated by quantitative analysis using offline ion chromatography. Nitrate (NO3-) and nitrite (NO2-) were found to be the dominant ions in the collected aerosols with values ranging between 87 and 343 ng m−3 at STP (standard temperature and pressure) during the summer campaign. In contrast, sulfate (SO42-) levels were found to be above the detection limit (>10 ng m−3 at STP) only in winter. In addition, we determined the origin of the air masses sampled during the flights using the analysis of back trajectories as well as a convective proxy from cloud-top temperature fields derived from a geostationary satellite. The results obtained from this analysis were put into the context of large-scale transport and aerosol distribution using GEOS-Chem chemical transport model simulations. The first flight in summer 2017 which sampled an air mass within the Asian monsoon anticyclone (AMA), influenced by convection over Western China, was associated with particle size diameters from 0.05 to 0.15 µm. In contrast, the second flight sampled air masses at the edge of the AMA associated with a larger particle size radius (>2 µm) with a higher NO2- concentration. The sampled air masses in winter 2018 were likely affected by smoke from the Pacific Northwest fire event in Canada, which occurred 7 months before our campaign, associated with concentration enhancements of SO42- and Ca2+. Overall, our results suggest that nitrogen-containing particles represent a large fraction of cloud-free and in-cloud aerosols populating the ATAL, which is partially in agreement with the results from aircraft measurements during the StratoClim (Stratospheric and upper tropospheric processes for better climate predictions) campaign. The exact nature of those particles is still unknown, but their coincidences with subvisible cirrus clouds and their sizes suggest nitric acid trihydrate (NAT) as a possible candidate, as NAT has already been observed in the tropical upper troposphere and lower stratosphere in other studies. Furthermore, GEOS-Chem model simulations indicate that lightning NOx emissions could have significantly impacted the production of nitrate aerosols sampled during the summer of 2017