Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions

Marine-produced short-lived trace gases such as dibromomethane (CH2Br2), bromoform (CHBr3), methyliodide (CH3I) and dimethyl sulfide (DMS) significantly impact tropospheric and stratospheric chemistry. Describing their marine emissions in atmospheric chemistry models as accurately as possible is necessary to quantify their impact on ozone depletion and Earth's radiative budget. So far, marine emissions of trace gases have mainly been prescribed from emission climatologies, thus lacking the interaction between the actual state of the atmosphere and the ocean. Here we present simulations with the chemistry climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry) with online calculation of emissions based on surface water concentrations, in contrast to directly prescribed emissions. Considering the actual state of the model atmosphere results in a concentration gradient consistent with model real-time conditions at the ocean surface and in the atmosphere, which determine the direction and magnitude of the computed flux. This method has a number of conceptual and practical benefits, as the modelled emission can respond consistently to changes in sea surface temperature, surface wind speed, sea ice cover and especially atmospheric mixing ratio. This online calculation could enhance, dampen or even invert the fluxes (i.e. deposition instead of emissions) of very short-lived substances (VSLS). We show that differences between prescribing emissions and prescribing concentrations (−28 % for CH2Br2 to +11 % for CHBr3) result mainly from consideration of the actual, time-varying state of the atmosphere. The absolute magnitude of the differences depends mainly on the surface ocean saturation of each particular gas. Comparison to observations from aircraft, ships and ground stations reveals that computing the air–sea flux interactively leads in most of the cases to more accurate atmospheric mixing ratios in the model compared to the computation from prescribed emissions. Calculating emissions online also enables effective testing of different air–sea transfer velocity (k) parameterizations, which was performed here for eight different parameterizations. The testing of these different k values is of special interest for DMS, as recently published parameterizations derived by direct flux measurements using eddy covariance measurements suggest decreasing k values at high wind speeds or a linear relationship with wind speed. Implementing these parameterizations reduces discrepancies in modelled DMS atmospheric mixing ratios and observations by a factor of 1.5 compared to parameterizations with a quadratic or cubic relationship to wind spee

Brominated VSLS and their influence on ozone under a changing climate

Very short-lived substances (VSLS) contribute as source gases significantly to the tropospheric and stratospheric bromine loading. At present, an estimated 25 % of stratospheric bromine is of oceanic origin. In this study, we investigate how climate change may impact the ocean–atmosphere flux of brominated VSLS, their atmospheric transport, and chemical transformations and evaluate how these changes will affect stratospheric ozone over the 21st century. Under the assumption of fixed ocean water concentrations and RCP6.0 scenario, we find an increase of the ocean–atmosphere flux of brominated VSLS of about 8–10 % by the end of the 21st century compared to present day. A decrease in the tropospheric mixing ratios of VSLS and an increase in the lower stratosphere are attributed to changes in atmospheric chemistry and transport. Our model simulations reveal that this increase is counteracted by a corresponding reduction of inorganic bromine. Therefore the total amount of bromine from VSLS in the stratosphere will not be changed by an increase in upwelling. Part of the increase of VSLS in the tropical lower stratosphere results from an increase in the corresponding tropopause height. As the depletion of stratospheric ozone due to bromine depends also on the availability of chlorine, we find the impact of bromine on stratospheric ozone at the end of the 21st century reduced compared to present day. Thus, these studies highlight the different factors influencing the role of brominated VSLS in a future climate

Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: The influence of prescribed water concentration vs. prescribed emissions

Marine-produced short-lived trace gases such as dibromomethane (CH$_{2}$Br$_{2}$), bromoform (CHBr$_{3}$), methyliodide (CH$_{3}$I) and dimethyl sulfide (DMS) significantly impact tropospheric and stratospheric chemistry. Describing their marine emissions in atmospheric chemistry models as accurately as possible is necessary to quantify their impact on ozone depletion and Earth’s radiative budget. So far, marine emissions of trace gases have mainly been prescribed from emission climatologies, thus lacking the interaction between the actual state of the atmosphere and the ocean. Here we present simulations with the chemistry climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry) with online calculation of emissions based on surface water concentrations, in contrast to directly prescribed emissions. Considering the actual state of the model atmosphere results in a concentration gradient consistent with model realtime conditions at the ocean surface and in the atmosphere, which determine the direction and magnitude of the computed flux. This method has a number of conceptual and practical benefits, as the modelled emission can respond consistently to changes in sea surface temperature, surface wind speed, sea ice cover and especially atmospheric mixing ratio. This online calculation could enhance, dampen or even invert the fluxes (i.e. deposition instead of emissions) of very short-lived substances (VSLS). We show that differences between prescribing emissions and prescribing concentrations (-28%for CH$_{2}$Br$_{2}$ to +11%for CHBr$_{3}$) result mainly from consideration of the actual, time-varying state of the atmosphere. The absolute magnitude of the differences depends mainly on the surface ocean saturation of each particular gas. Comparison to observations from aircraft, ships and ground stations reveals that computing the air–sea flux interactively leads in most of the cases to more accurate atmospheric mixing ratios in the model compared to the computation from prescribed emissions. Calculating emissions online also enables effective testing of different air–sea transfer velocity (k) parameterizations, which was performed here for eight different parameterizations. The testing of these different k values is of special interest for DMS, as recently published parameterizations derived by direct flux measurements using eddy covariance measurements suggest decreasing k values at high wind speeds or a linear relationship with wind speed. Implementing these parameterizations reduces discrepancies in modelled DMS atmospheric mixing ratios and observations by a factor of 1.5 compared to parameterizations with a quadratic or cubic relationship to wind speed

A database of aircraft measurements of carbon monoxide (CO) with high temporal and spatial resolution during 2011–2021

To understand tropospheric air pollution at regional and global scales, the SPIRIT (SPectromètre Infra-Rouge In situ Toute altitude) airborne instrument was developed and used on aircraft to measure volume mixing ratios of carbon monoxide (CO), an important indicator of air pollution, during the last decade. SPIRIT provides high-quality CO measurements with 1σ precision of 0.3 ppbv at a time resolution of 1.6 s thanks to the coupling of a quantum cascade laser to a Robert optical multi-pass cell. It can be operated on different aircraft such as Falcon-20 and ATR-42 from the German Aerospace Agency (DLR) and from SAFIRE (CNRS-CNES-Météo France). With support from various projects, measurements were taken for more than 200 flight hours over three continents (Europe, Asia, and Africa), including two intercontinental transects (Europe–Asia and Europe–Africa). Levels of CO and its spatial distribution are briefly discussed and compared between different regions/continents. CO generally decreases with altitude except in some cases, indicating the important contribution of long-distance transport to CO levels. A 3D trajectory mapped by CO level was plotted for each flight and is presented in this study (which includes a Supplement). The database is archived in the AERIS database (https://doi.org/10.25326/440), the French national center for atmospheric observations (Catoire et al., 2023). In addition, it could help to validate model performance and satellite measurements. For instance, the database covers measurements at high-latitude regions (i.e., Kiruna, Sweden, 68∘ N), where satellite measurements are still challenging, and at low-latitude regions (West Africa and Southeast Asia), where in situ data are scarce and satellites need more validation by airborne measurements.</p

Stratospheric aerosols from the Sarychev volcano eruption in the 2009 Arctic summer

Aerosols from the Sarychev volcano eruption (Kuril Islands, northeast of Japan) were observed in the Arctic lower stratosphere a few days after the strongest SO2 injection which occurred on 15 and 16 June 2009. From the observations provided by the Infrared Atmospheric Sounding Interferometer (IASI) an estimated 0.9 Tg of sulphur dioxide was injected into the upper troposphere and lower stratosphere (UTLS). The resultant stratospheric sulphate aerosols were detected from satellites by the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb sounder and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and from the surface by the Network for the Detection of Atmospheric Composition Changes (NDACC) lidar deployed at OHP (Observatoire de Haute-Provence, France). By the first week of July the aerosol plume had spread out over the entire Arctic region. The Sarychev-induced stratospheric aerosol over the Kiruna region (north of Sweden) was measured by the Stratospheric and Tropospheric Aerosol Counter (STAC) during eight balloon flights planned in August and September 2009. During this balloon campaign the Micro Radiomètre Ballon (MicroRADIBAL) and the Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON) remote-sensing instruments also observed these aerosols. Aerosol concentrations returned to near-background levels by spring 2010. The effective radius, the surface area density (SAD), the aerosol extinction, and the total sulphur mass from STAC in situ measurements are enhanced with mean values in the range 0.15-0.21 μm, 5.5-14.7 μm2 cm-3, 5.5-29.5 × 10-4 km-1, and 4.9-12.6 × 10-10 kg[S] kg-1[air], respectively, between 14 km and 18 km. The observed and modelled e-folding time of sulphate aerosols from the Sarychev eruption is around 70-80 days, a value much shorter than the 12-14 months calculated for aerosols from the 1991 eruption of Mt Pinatubo. The OSIRIS stratospheric aerosol optical depth (AOD) at 750 nm is enhanced by a factor of 6, with a value of 0.02 in late July compared to 0.0035 before the eruption. The HadGEM2 and MIMOSA model outputs indicate that aerosol layers in polar region up to 14-15 km are largely modulated by stratosphere-troposphere exchange processes. The spatial extent of the Sarychev plume is well represented in the HadGEM2 model with lower altitudes of the plume being controlled by upper tropospheric troughs which displace the plume downward and upper altitudes around 18-20 km, in agreement with lidar observations. Good consistency is found between the HadGEM2 sulphur mass density and the value inferred from the STAC observations, with a maximum located about 1 km above the tropopause ranging from 1 to 2 × 10 -9 kg[S] kg-1[air], which is one order of magnitude higher than the background level. © Author(s) 2013.The authors thank the CNES balloon launching team for successful operations and the Swedish Space Corporation at Esrange. The ETHER database (CNES-INSUCNRS) and the CNES “sous-direction Ballon” are partners of the project. The StraPolEt ´ e project has been funded by the French ´ “Agence Nationale de la Recherche” (ANR-BLAN08-1-31627), the “Centre National d’Etudes Spatiales” (CNES), and the “Institut ´ Polaire Paul-Emile Victor” (IPEV). The AEROWAVE (Aerosols, Water Vapor and Electricity) and the HALOHA (HALOgen in High Altitudes) projects have been funded by the recently created French CNES-INSU Balloon Committee (so-called CSTB). We are grateful to Slimane Bekki and David Cugniet for their constructive comments about the AER-UPMC 2-D model, to Marc-Antoine Drouin for his help about the MIMOSA model, and to the LPC2E technical team for this successful campaign. Jim Haywood and Andy Jones were supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). IASI was developed and built under the responsibility of the Centre National d’Etudes Spatiales (CNES, France). It is flown on board the Metop ´ satellites as part of the EUMETSAT Polar System. The IASI L1 data are received through the EUMETCast near-real-time data distribution service. L. Clarisse is a postdoctoral researcher with FRS-FNRS. We acknowledge the CALIOP team for acquiring and processing data as well as the ICARE team for providing and maintaining the computational facilities to store them. Odin is a Swedish-led satellite project funded jointly by Sweden (SNSB), Canada (CSA), France (CNES), and Finland (Tekes). This study was supported by the French VOLTAIRE Labex (Laboratoire d’Excellence ANR-10-LABX-100-01) managed by the University of Orleans

Modelling the chemistry and transport of bromoform within a sea breeze driven convective system during the SHIVA Campaign

We carry out a case study of the transport and chemistry of bromoform and its product gases (PGs) in a sea breeze driven convective episode on 19 November 2011 along the North West coast of Borneo during the "Stratospheric ozone: Halogen Impacts in a Varying Atmosphere" (SHIVA) campaign. We use ground based, ship, aircraft and balloon sonde observations made during the campaign, and a 3-D regional online transport and chemistry model capable of resolving clouds and convection explicitly that includes detailed bromine chemistry. The model simulates the temperature, wind speed, wind direction fairly well for the most part, and adequately captures the convection location, timing, and intensity. The simulated transport of bromoform from the boundary layer up to 12 km compares well to aircraft observations to support our conclusions. The model makes several predictions regarding bromine transport from the boundary layer to the level of convective detrainment (11 to 12 km). First, the majority of bromine undergoes this transport as bromoform. Second, insoluble organic bromine carbonyl species are transported to between 11 and 12 km, but only form a small proportion of the transported bromine. Third, soluble bromine species, which include bromine organic peroxides, hydrobromic acid (HBr), and hypobromous acid (HOBr), are washed out efficiently within the core of the convective column. Fourth, insoluble inorganic bromine species (principally Br2) are not washed out of the convective column, but are also not transported to the altitude of detrainment in large quantities. We expect that Br2 will make a larger relative contribution to the total vertical transport of bromine atoms in scenarios with higher CHBr3 mixing ratios in the boundary layer, which have been observed in other regions. Finally, given the highly detailed description of the chemistry, transport and washout of bromine compounds within our simulations, we make a series of recommendations about the physical and chemical processes that should be represented in 3-D chemical transport models (CTMs) and chemistry climate models (CCMs), which are the primary theoretical means of estimating the contribution made by CHBr3 and other very short-lived substances (VSLS) to the stratospheric bromine budget

A multi-model intercomparison of halogenated very short-lived substances (TransCom-VSLS): Linking oceanic emissions and tropospheric transport for a reconciled estimate of the stratospheric source gas injection of bromine

Abstract. The first concerted multi-model intercomparison of halogenated very short-lived substances (VSLS) has been performed, within the framework of the ongoing Atmospheric Tracer Transport Model Intercomparison Project (TransCom). Eleven global models or model variants participated (nine chemical transport models and two chemistry–climate models) by simulating the major natural bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2), over a 20-year period (1993–2012). Except for three model simulations, all others were driven offline by (or nudged to) reanalysed meteorology. The overarching goal of TransCom-VSLS was to provide a reconciled model estimate of the stratospheric source gas injection (SGI) of bromine from these gases, to constrain the current measurement-derived range, and to investigate inter-model differences due to emissions and transport processes. Models ran with standardised idealised chemistry, to isolate differences due to transport, and we investigated the sensitivity of results to a range of VSLS emission inventories. Models were tested in their ability to reproduce the observed seasonal and spatial distribution of VSLS at the surface, using measurements from NOAA's long-term global monitoring network, and in the tropical troposphere, using recent aircraft measurements – including high-altitude observations from the NASA Global Hawk platform. The models generally capture the observed seasonal cycle of surface CHBr3 and CH2Br2 well, with a strong model–measurement correlation (r  ≥  0.7) at most sites. In a given model, the absolute model–measurement agreement at the surface is highly sensitive to the choice of emissions. Large inter-model differences are apparent when using the same emission inventory, highlighting the challenges faced in evaluating such inventories at the global scale. Across the ensemble, most consistency is found within the tropics where most of the models (8 out of 11) achieve best agreement to surface CHBr3 observations using the lowest of the three CHBr3 emission inventories tested (similarly, 8 out of 11 models for CH2Br2). In general, the models reproduce observations of CHBr3 and CH2Br2 obtained in the tropical tropopause layer (TTL) at various locations throughout the Pacific well. Zonal variability in VSLS loading in the TTL is generally consistent among models, with CHBr3 (and to a lesser extent CH2Br2) most elevated over the tropical western Pacific during boreal winter. The models also indicate the Asian monsoon during boreal summer to be an important pathway for VSLS reaching the stratosphere, though the strength of this signal varies considerably among models. We derive an ensemble climatological mean estimate of the stratospheric bromine SGI from CHBr3 and CH2Br2 of 2.0 (1.2–2.5) ppt,  ∼  57 % larger than the best estimate from the most recent World Meteorological Organization (WMO) Ozone Assessment Report. We find no evidence for a long-term, transport-driven trend in the stratospheric SGI of bromine over the simulation period. The transport-driven interannual variability in the annual mean bromine SGI is of the order of ±5 %, with SGI exhibiting a strong positive correlation with the El Niño–Southern Oscillation (ENSO) in the eastern Pacific. Overall, our results do not show systematic differences between models specific to the choice of reanalysis meteorology, rather clear differences are seen related to differences in the implementation of transport processes in the models. </jats:p

Description of research methodology of main rotors wind tunnel tests in terms of autorotation teetering autogyro!s rotor modelling

Niniejszy artykuł zawiera opis przygotowań i sposób realizacji pomiarów obciążeń aerodynamicznych modelu wirnika wiatrakowca I-28 wykonanego w skali 1:3 przeprowadzonych w ramach projektu: „Technologia wdrożenia do praktyki gospodarczej nowego typu wiropłatowego statku powietrznego”. Zakres prac obejmował projekt, wykonanie i badania modelu wirnika z odwzorowaniem kinematyki ruchów rzeczywistego obiektu. W ramach pracy wykonano, uwzględniając kryteria podobieństwa dynamicznego i geometrycznego, kompozytowe łopaty modelowego wirnika. Dostosowano stanowisko do badań wiropłatów do potrzeb niniejszego projektu. Wykonano wahliwą głowicę wirnika oraz przeprowadzono próby wytrzymałościowe newralgicznych elementów głowicy. Opracowano i wdrożono zaawansowany program do zbierania i przeliczania danych pomiarowych. Cześć badawcza została przeprowadzona w Instytucie Lotnictwa w tunelu aerodynamicznym o średnicy 5 metrów z otwartą przestrzenią pomiarową. Model wirnika zamontowano na ustawionym w przestrzeni pomiarowej stanowisku. Badania przeprowadzono przy użyciu wagi tensometrycznej umieszczonej wewnątrz jednostki pomiarowo-sterującej „PS”. Mierzono sześć składowych obciążeń aerodynamicznych w tym trzy siły i trzy momenty oraz siłę w popychaczu łopat i kąt wahań wirnika. Ze względu na specyficzny charakter testowanego obiektu jakim jest wiatrakowiec w badaniach wirnika zwrócono szczególną uwagę na pomiary w stanach autorotacji. W badaniach nie uwzględniono wpływu ziemi oraz obecności śmigła napędowego wiatrakowca. Artykuł może posłużyć jako kompendium wiedzy w prowadzeniu wirnikowych badań tunelowych, zawiera przy tym cenne wskazówki co do zakresu koniecznych do przeprowadzenia prac pomocniczych.This article describes the preparation and performance of aerodynamic characteristics measurement of an I-28 autogyro’s rotor model made in 1:3 scale carried out under the „Technology of Implementing in the Economic Practice of a New Type of Rotary-Wing Aircraft” project. The scope of work included the design, manufacturing and testing of the rotor’s model. The work included manufacturing of composite rotor’s blades, taking into account the criteria for dynamic and geometric similarity. The stand for rotors research was adjusted for the purpose of this project. A teetering rotor’s head was made and strength tests of critical elements of the rotor’s head were carried out. An advanced system for collecting and converting measurement data was developed and implemented. The research part was performed at the Institute of Aviation in the 5 - meter diameter wind tunnel with open space section. The model was mounted on the rotor station set in the test section. The tests were performed using the six components strain gauge balance placed in the „PS” control unit. Special attention was paid to autorotation conditions of the rotor. The study does not include the impact of ground and the presence of the autogyros’ propeller drive. The article may serve as a source of knowledge in other rotors’ tunnel tests and provides valuable guidance as to the range of ancillary works which need to be carried out

Economic analysis of design and operation of internet communications systems in an agricultural enterprise

Celem pracy była budowa systemu telefonii internetowej w oparciu o istniejącą infrastrukturę teleinformatyczną w przedsiębiorstwie rolniczym oraz porównanie kosztów eksploatacji zbudowanego systemu z dotychczas użytkowanym. W pracy przedstawiono porównanie kosztów rozmów telefonicznych przy użyciu VoIP w stosunku do kosztów rozmów realizowanych przy pomocy standardowych łączy analogowych POTS. Przedstawiono także rozwiązanie sprzętowe tego przedsięwzięcia. Jak wykazano w pracy koszty ponoszone na rozmowy telefoniczne z użyciem VoIP mogą stanowić znaczący element budżetu przedsiębiorstwa, gdyż są one o ponad połowę tańsze w stosunku do tradycyjnych rozwiązań. Badania zostały przeprowadzone w trzech przedsiębiorstwach rolniczych przez okres trzech miesięcy 2006 roku.The purpose of the work was to design an internet communications system based on an existing data transmission infrastructure in an agricultural enterprise, and to compare operating costs of a new-built system with the system operated so far. The paper presents costs for telephone calls being made using the VoIP, compared to costs of calls via standard POTS analog links. Moreover, it shows the concept of equipment, which should be used in this project. As it has been shown in the paper, telephone calls via VoIP may be important for an enterprise budget, since their costs are more than twice lower than conventional communication. The research was carried out in three agricultural enterprises for three months in 2006