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We outlined five studies regarding the quality of the review by committees based on the Act on the Safety of Regenerative Medicine. The findings raise serious concerns about the independence, integrity, and quality of reviews of therapeutic plans by these committees with inappropriately close relationships to medical institutions and companies., 自由診療で行われる再生医療の審査に関する課題を調査 今後の制度改正に期待. 京都大学プレスリリース. 2023-02-28., Questionable practices identified by an examination of therapeutic plan reviews performed by certified committees under the Act on the Safety of Regenerative Medicine. 京都大学プレスリリース. 2023-02-28.

Anthropogenic and natural emissions contribute to enhanced concentrations of aerosols in the Arctic winter and early spring, with most attention being paid to anthropogenic aerosols that contribute to so-called Arctic haze. Less-well-studied wintertime sea-spray aerosols (SSAs) under Arctic haze conditions are the focus of this study, since they can make an important contribution to wintertime Arctic aerosol abundances. Analysis of field campaign data shows evidence for enhanced local sources of SSAs, including marine organics at Utqiaġvik (formerly known as Barrow) in northern Alaska, United States, during winter 2014. Models tend to underestimate sub-micron SSAs and overestimate super-micron SSAs in the Arctic during winter, including the base version of the Weather Research Forecast coupled with Chemistry (WRF-Chem) model used here, which includes a widely used SSA source function based on Gong et al. (1997). Quasi-hemispheric simulations for winter 2014 including updated wind speed and sea-surface temperature (SST) SSA emission dependencies and sources of marine sea-salt organics and sea-salt sulfate lead to significantly improved model performance compared to observations at remote Arctic sites, notably for coarse-mode sodium and chloride, which are reduced. The improved model also simulates more realistic contributions of SSAs to inorganic aerosols at different sites, ranging from 20 %–93 % in the observations. Two-thirds of the improved model performance is from the inclusion of the dependence on SSTs. The simulation of nitrate aerosols is also improved due to less heterogeneous uptake of nitric acid on SSAs in the coarse mode and related increases in fine-mode nitrate. This highlights the importance of interactions between natural SSAs and inorganic anthropogenic aerosols that contribute to Arctic haze. Simulation of organic aerosols and the fraction of sea-salt sulfate are also improved compared to observations. However, the model underestimates episodes with elevated observed concentrations of SSA components and sub-micron non-sea-salt sulfate at some Arctic sites, notably at Utqiaġvik. Possible reasons are explored in higher-resolution runs over northern Alaska for periods corresponding to the Utqiaġvik field campaign in January and February 2014. The addition of a local source of sea-salt marine organics, based on the campaign data, increases modelled organic aerosols over northern Alaska. However, comparison with previous available data suggests that local natural sources from open leads, as well as local anthropogenic sources, are underestimated in the model. Missing local anthropogenic sources may also explain the low modelled (sub-micron) non-sea-salt sulfate at Utqiaġvik. The introduction of a higher wind speed dependence for sub-micron SSA emissions, also based on Arctic data, reduces biases in modelled sub-micron SSAs, while sea-ice fractions, including open leads, are shown to be an important factor controlling modelled super-micron, rather than sub-micron, SSAs over the north coast of Alaska. The regional results presented here show that modelled SSAs are more sensitive to wind speed dependence but that realistic modelling of sea-ice distributions is needed for the simulation of local SSAs, including marine organics. This study supports findings from the Utqiaġvik field campaign that open leads are the primary source of fresh and aged SSAs, including marine organic aerosols, during wintertime at Utqiaġvik; these findings do not suggest an influence from blowing snow and frost flowers. To improve model simulations of Arctic wintertime aerosols, new field data on processes that influence wintertime SSA production, in particular for fine-mode aerosols, are needed as is improved understanding about possible local anthropogenic sources.

As the third most important greenhouse gas (GHG) after carbon dioxide (CO2) and methane (CH4), tropospheric ozone (O3) is also an air pollutant causing damage to human health and ecosystems. This study brings together recent research on observations and modeling of tropospheric O3 in the Arctic, a rapidly warming and sensitive environment. At different locations in the Arctic, the observed surface O3 seasonal cycles are quite different. Coastal Arctic locations, for example, have a minimum in the springtime due to O3 depletion events resulting from surface bromine chemistry. In contrast, other Arctic locations have a maximum in the spring. The 12 state-of-the-art models used in this study lack the surface halogen chemistry needed to simulate coastal Arctic surface O3 depletion in the springtime; however, the multi-model median (MMM) has accurate seasonal cycles at non-coastal Arctic locations. There is a large amount of variability among models, which has been previously reported, and we show that there continues to be no convergence among models or improved accuracy in simulating tropospheric O3 and its precursor species. The MMM underestimates Arctic surface O3 by 5 % to 15 % depending on the location. The vertical distribution of tropospheric O3 is studied from recent ozonesonde measurements and the models. The models are highly variable, simulating free-tropospheric O3 within a range of ±50 % depending on the model and the altitude. The MMM performs best, within ±8 % for most locations and seasons. However, nearly all models overestimate O3 near the tropopause (∼300 hPa or ∼8 km), likely due to ongoing issues with underestimating the altitude of the tropopause and excessive downward transport of stratospheric O3 at high latitudes. For example, the MMM is biased high by about 20 % at Eureka. Observed and simulated O3 precursors (CO, NOx, and reservoir PAN) are evaluated throughout the troposphere. Models underestimate wintertime CO everywhere, likely due to a combination of underestimating CO emissions and possibly overestimating OH. Throughout the vertical profile (compared to aircraft measurements), the MMM underestimates both CO and NOx but overestimates PAN. Perhaps as a result of competing deficiencies, the MMM O3 matches the observed O3 reasonably well. Our findings suggest that despite model updates over the last decade, model results are as highly variable as ever and have not increased in accuracy for representing Arctic tropospheric O3.

International audience; Integrative and Comprehensive Understanding on Polar Environments (iCUPE) project developed 24 novel datasets utilizing in-situ observational capacities within the Arctic or remote sensing observations from ground or from space. The datasets covered atmospheric, cryospheric, marine, and terrestrial domains. This paper connects the iCUPE datasets to United Nations’ Sustainable Development Goals and showcases the use of selected datasets as knowledge provision services for policy- and decision-making actions. Inclusion of indigenous and societal knowledge into the data processing pipelines enables a feedback mechanism that facilitates data driven public services.

As the third most important greenhouse gas (GHG) after CO2 and methane, tropospheric ozone (O3) is also an air pollutant causing damage to human health and ecosystems. This study brings together recent research on observations and modeling of tropospheric O3 in the Arctic, a rapidly warming and sensitive environment. At different locations in the Arctic, the observed surface O3 seasonal cycles are quite different. Coastal Arctic locations, for example, have a minimum in the springtime due to O3 depletion events resulting from surface bromine chemistry. In contrast, other Arctic locations have a maximum in the spring. The 12 state-of-the-art models used in this study lack the surface halogen chemistry needed to simulate coastal Arctic surface O3 depletion in the springtime, however, the multi-model median (MMM) has accurate seasonal cycles at non-coastal Arctic locations. There is a large amount of variability among models, which has been reported previously, and we show that there continues to be no convergence among models, nor improved accuracy in simulating tropospheric O3 and its precursor species. The MMM underestimates Arctic surface O3 by 5 % to 15 % depending on the location. The vertical distribution of tropospheric O3 is studied from recent ozonesonde measurements and the models. The models are highly variable, simulating free-tropospheric O3 within a range of +/- 50 % depending on the model and the altitude. The MMM performs best, within +/- 8 % at most locations and seasons. However, nearly all models overestimate O3 near the tropopause (~300 hPa or ~8 km), likely due to ongoing issues with underestimating the altitude of the tropopause and excessive downward transport of stratospheric O3 at high latitudes. For example, the MMM is biased high by about 20 % at Eureka. Observed and simulated O3 precursors (CO, NOx and reservoir PAN) are evaluated throughout the troposphere. Models underestimate wintertime CO everywhere, likely due to a combination of underestimating CO emissions and possibly overestimating OH. Throughout the vertical profile (compared to aircraft measurements), the MMM underestimates both CO and NOx but overestimates PAN. Perhaps as a result of competing deficiencies, the MMM O3 matches the observed O3 reasonably well. Our findings suggest that despite model updates over the last decade , model results are as highly variable as ever, and have not increased in accuracy for representing Arctic tropospheric.

The Arctic atmosphere is warming rapidly and its relatively pristine environment is sensitive to the long-range transport of atmospheric pollutants. While carbon dioxide is the main cause for global warming, short-lived climate forcers (SLCFs) such as methane, ozone, and particles also play a role in Arctic climate on near-term time scales. Atmospheric modelling is critical for understanding the abundance and distribution of SLCFs throughout the Arctic atmosphere, and is used as a tool towards determining SLCF impacts on climate and health in the present and in future emissions scenarios. In this study, we evaluate 18 state-of-the-art atmospheric and Earth system models, assessing their representation of Arctic and Northern Hemisphere atmospheric SLCF distributions, considering a wide range of different chemical species (methane, tropospheric ozone and its precursors, black carbon, sulfate, organic aerosol, and particulate matter) and multiple observational datasets. Model simulations over four years (2008–2009 and 2014–2015) conducted for the 2021 Arctic Monitoring and Assessment Programme (AMAP) SLCF assessment report are thoroughly evaluated against satellite, ground, ship and aircraft-based observations. The results show a large range in model performance, with no one particular model or model type performing well for all regions and all SLCF species. The multi-model mean was able to represent the general features of SLCFs in the Arctic, though vertical mixing, long-range transport, deposition, and wildfire emissions remain highly uncertain processes. These need better representation within atmospheric models to improve their simulation of SLCFs in the Arctic environment.

International audience; The Arctic is influenced by long-range transport of air masses from mid-latitudes, during winter and spring. There are also local sources within the Arctic region, such as combustion for heating and power production, leading to enhance aerosol concentrations in remote sites. However, the formation of secondary aerosol particles in the dark wintertime Arctic conditions is poorly understood. In this study, which contributes to the Air Pollution in the Arctic: Climate, Environment and Societies - Alaskan Layered Pollution and Chemical Analysis (PACES-ALPACA) initiative, the Weather Research Forecasting Model with chemistry (WRF-Chem) is used to investigate wintertime pollution over central Alaska, focusing on the Fairbanks region, during the pre-ALPACA campaign in winter 2019. Fairbanks is the most polluted city in the United States during winter due to high local emissions and the occurrence of strong surface temperature inversions trapping pollutants near the surface. During the pre-ALPACA campaign aerosols, oxidants and aerosol precursors, were measured in key locations in Fairbanks, including vertical profile data collected in the lowest 20m, with the aim to identify the origins of aerosols during pollution episodes. A quasi-hemispheric WRF-Chem simulation, using an improved WRF set-up with increased vertical resolution below 2km, is used to assess large-scale synoptic conditions and to evaluate Arctic Haze, influencing central Alaska. The model was run with Copernicus Atmosphere Monitoring System v4.2 anthropogenic emissions, with an initial horizontal resolution of 10x10km. Discrepancies in modelled aerosols compared to available data are investigated (missing dark formation mechanisms, treatment of removal processes). Fine-resolution WRF-Chem simulations, including local point sources, over the Fairbanks region are used to explore chemical and dynamical processes influencing aerosol formation under different meteorological conditions observed during the campaign, including a cold stable episode and a period with possible mixing of air masses from aloft. Model results are evaluated against data from surface monitoring sites and collected during the campaign. The sensitivity of modelled aerosols to meteorological factors (relative humidity, vertical mixing) are examined.

International audience; Air pollution transported from mid-latitudes influences the Arctic during wintertime, leading to the formation of Arctic Haze.Local emissions, such as combustion for heating in cold winter conditions, also contribute to wintertime air pollution. However,the formation of secondary aerosol particles in cold/dark wintertime Arctic conditions, is poorly understood.In this study, which contributes to the Air Pollution in the Arctic: Climate, Environment and Societies - Alaskan Layered Pollutionand Arctic Chemical Analysis (PACES-ALPACA) initiative, the Weather Research Forecasting Model with chemistry (WRF-Chem) is used to investigate wintertime pollution over Alaska focusing on Prudhoe Bay and the Fairbanks region,respectively. Fairbanks is the most polluted city in the United States during wintertime, due to high local emissions and theoccurrence of strong surface temperature inversions trapping pollutants near the surface. On the other hand, the Prudhoe Bayoilfields contribute to wintertime air pollution in northern Alaska.In a first study, the sensitivity of simulated aerosols to local anthropogenic emissions is investigated over northern Alaska andevaluated against observations at Utqiaġvik, collected during a campaign in Jan-Feb 2014. FLEXible PARTicle dispersionmodel coupled with WRF, is also used to identify the pollutant origins in air masses in the boundary layer, which are influencingUtqiaġvik during periods with elevated aerosols. The contribution of locally produced anthropogenic and natural aerosolsrelative to remote pollutants is also examined.In a second study, focusing on winter 2019 (ALPACA pre-campaign) over Fairbanks, large-scale synoptic conditions and remote anthropogenic sources affecting background aerosols are estimated. The sensitivity ofsecondary aerosol formation to meteorological factors, such as relative humidity, boundary layer stability are examined.Discrepancies in modelled secondary aerosols compared to available data are investigated (e.g. missing dark formationmechanisms, removal processes, emissions). The role of local/regional dynamical processes influencing aerosols under differentmeteorological conditions observed during the field campaign, such as a cold stable episode or a period with potential mixing ofair masses from aloft, are also investigated.

The wintertime Arctic is influenced by air pollution transported from mid-latitudes, leading to formation of Arctic Haze, as well as local emissions such as combustion for heating and power production in very cold winter conditions. This contributes to severe air pollution episodes, with enhanced aerosol concentrations, inter-dispersed with cleaner periods. However, the formation of secondary aerosol particles (sulphate, organics, nitrate) in cold/dark wintertime Arctic conditions, which could contribute to these pollution episodes, is poorly understood.In this study, which contributes to the Air Pollution in the Arctic: Climate, Environment and Societies - Alaskan Layered Pollution and Arctic Chemical Analysis (PACES-ALPACA) initiative, the Weather Research Forecasting Model with chemistry (WRF-Chem) is used to investigate wintertime pollution over central Alaska focusing on the Fairbanks region, during the pre-ALPACA campaign in winter 2019-2020. Fairbanks is the most polluted city in the United States during wintertime, due to high local emissions and the occurrence of strong surface temperature inversions trapping pollutants near the surface.Firstly, different WRF meteorological and surface schemes were tested over Alaska with a particular focus on improving simulations of the wintertime boundary layer structure including temperature inversions. An optimal WRF set-up, with increased vertical resolution below 2km, was selected based on evaluation against available data.Secondly, a quasi-hemispheric WRF-Chem simulation, using the improved WRF setup, was used to assess large-scale synoptic conditions and to evaluate background aerosols originating from remote anthropogenic and natural sources affecting central Alaska during the campaign. The model was run with Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants (ECLIPSE) v6b anthropogenic emissions and improved sea-spray aerosol emissions. Discrepancies in modelled aerosols compared available data are being investigated (e.g. missing dark formation mechanisms, treatment of removal processes).Thirdly, fine resolution simulations, using high resolution emissions (e.g. 2019 CAMS inventory), including local point sources, over the Fairbanks region, were used to investigate chemical and dynamical processes influencing aerosols under different meteorological conditions observed during the field campaign including a cold stable episode and a period with possible mixing of air masses from aloft. The model was evaluated against available aerosol, oxidant (ozone) and aerosol precursor data from surface monitoring sites and collected during the pre-campaign, including vertical profile data collected in the lowest 20m. The sensitivity of modelled aerosols to meteorological factors, such as relative humidity, temperature gradients and vertical mixing under winter conditions are investigated.

International audience; Arctic air pollution originates mainly from long-range transport of short-lived climate forcers (SLCFs), including black carbon(BC), ozone, and their precursors, from mid-latitudes and, also from important local anthropogenic emissions from activities suchas resource extraction, shipping and domestic combustion. Russia’s location closer to the Arctic leads to more significantcontributions from local anthropogenic emissions to levels of Arctic air pollution, especially BC from oil/gas extraction activities.However, large uncertainties exist about the magnitude and temporal/spatial variations of BC emissions and their contribution toArctic BC loading. In this study, we focus on a better understanding of BC emissions from gas flaring hot spots in the Yamal-Nenets regions of northern Russia by using WRF-Chem simulations with improved BC emissions estimated from radiometerscanning night-light imaging from satellite data. For this study, we convert VIIRS (Visible Infrared Imaging Radiometer Suite)12-hourly heat radiances (Elvidge et al. 2016) from Russian gas/oil flaring hot spots into daily BC emission, by using correlationswith 0.025 degree annual BC emissions derived from Sea and Land Surface Temperature Radiometer (SLSTR) GFlaringS3 data(Caseiro et al. 2020). We analyze the origins of polluted air masses sampled during French (CNRS)-Russian YAK-AEROSIBflights over the Ob Valley, Yamal and Kara Sea regions during October 2014 using BC tracers run in WRF-Chem. Fullchemistry-aerosol simulations of WRF-Chem, run with SAPRC-MOSAIC and ECLIPSE-v6b anthropogenic emissions, are usedto examine the sensitivity of simulated BC to gas flaring emissions. BC emissions from the flaring sector are replaced withemissions derived from VIIRS data. Sensitivity runs with daily varying and annual average BC are also performed to examine theimpacts of temporal variations in flaring activities on Arctic BC

International audience; The Arctic is influenced by long-range transport of aerosols from mid-latitude emissions, especially in winter and spring, leading to formation of Arctic Haze. Natural aerosols, such as sea-salt, also contribute to wintertime Arctic aerosol loadings. Local sources of aerosols are highlighted as being important, but many uncertainties remain about the relative contributions of natural and anthropogenic sources and aerosol processes. In particular, models have difficulties reproducing observed aerosol distributions and composition.In this study, the Weather Research Forecasting Model with chemistry (WRF-Chem) is used to investigate origins of wintertime aerosols over northern Alaska focusing on the influence of local versus remote sources and examining the role of meteorology, in particular, stable boundary layers that can trap aerosols near the surface. The model was run first in hemispheric mode using AMAP-ECLIPSEv6 anthropogenic emissions and a dynamical (WRF) setup for improved simulation of cold, stable meteorological conditions over wintertime Alaska. Model results are evaluated against available surface data and, in particular, data collected at Utqiaġvik during January-February 2014. A variety of air masses were sampled including air masses originating from the Arctic Ocean and from the North Slope of Alaska oil and gas extraction emissions to the east on the northern coast of Alaska.We investigate the ability of the model to reproduce observed natural aerosols, especially local and transported sea-salt and marine organic aerosols. The sensitivity of modelled aerosols and natural emissions to, for example, sea-ice fraction, surface winds, and relative humidity, are examined, as well as model treatments of marine organic aerosols. We also investigate the ability of the model to reproduce anthropogenic aerosols originating from remote sources and runs including local emissions are used to assess the influence of aerosols originating from the North Slope of Alaska oil fields. Simulations at higher resolutions over northern Alaska are also used to examine the effect of increasing model resolution on simulated meteorology and boundary layer aerosols. The results are used to estimate the relative contributions of local and remote natural and anthropogenic aerosols to wintertime aerosols over northern Alaska.

In the Arctic, during polar night and early spring, ice clouds are separated into two leading types: (1) TIC1 clouds characterized by large concentration of very small crystals, and TIC2 clouds characterized by low concentration of large ice crystals. Using suitable parameterization of heterogeneous ice nucleation is essential for properly representing ice cloud in meteorological and climate model and subsequently understanding their interactions with aerosols and radiation. Here, we describe a new parameterization for ice crystals formation by heterogeneous nucleation coupled to aerosols chemistry in WRF-Chem. The parameterization is implemented in the Milbrandt and Yau’s two-moment cloud microphysics scheme and we assess how the WRF-Chem model responds to the real time interaction between chemistry and the new parameterization. Well-documented reference cases provided us in situ data from the spring 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) campaign over Alaska. Our analysis reveals that the new parameterization clearly improves the representation of the IWC in polluted or unpolluted air masses and shows the poor performance of the reference parameterization in representing ice clouds with low IWC. The new parameterization is, thus able to represent TIC1 and TIC2 microphysical characteristics at the top of the clouds were heterogeneous ice nucleation is most likely occurring even knowing the bias of simulated aerosols by WRF-Chem over Arctic.

Arctic warming leading to reduced summertime sea-ice is likely to lead to increased local shipping especially along the Northeast Passage near the northern coasts of Norway and Russia, which are shorter than the traditional southerly routes. Here, the regional chemistry-transport model WRF-Chem is used to examine the effects of shipping emissions on levels of air pollutants and deposition fluxes over the Barents Sea both for present-day and future conditions, based on a high growth scenario. Present-day shipping emissions are found to have already substantial effects on ozone concentrations, but limited effects on sulphate and nitrate aerosols. Predicted future changes in ozone are also important, particularly in regions with low nitrogen oxide concentrations, and results are sensitive to the way in which diversion shipping is distributed due to non-linear effects on photochemical ozone production. Whilst modest future increases in sulphate and nitrate aerosols are predicted, large enhancements in dry deposition of sulphur dioxide and wet deposition of nitrogen compounds to the Barents Sea are predicted. Such levels of future nitrogen deposition would represent a significant atmospheric source of oceanic nitrogen affecting sensitive marine ecosystems.

The Arctic is influenced by long-range transport of aerosols, for example, sulphate, black carbon, and dust from mid-latitude emissions, especially in winter and spring, leading to the formation of Arctic Haze with enhanced aerosol concentrations. However, more recently, local sources of aerosols, such as wood-burning or resource extraction, are highlighted as already being important, but many uncertainties about sources and aerosol processes still remain. For example, the formation of secondary aerosols, such as sulphate, in winter despite very low temperatures and the absence of sunlight. In this study, which contributes to the international PACES-ALPACA initiative, the Weather Research Forecasting (WRF) and WRF-Chem models are used to investigate wintertime pollution over Alaska with a focus on regions influenced by local pollution, such as Fairbanks and by Arctic Haze, such as Utqiagvik (formerly known as Barrow). Fairbanks is the most polluted city in the United States during wintertime due to high emissions and the occurrence of strong surface temperature inversions. As a first step, background aerosols originating from remote sources were evaluated in large- scale quasi-hemispheric WRF-Chem runs using ECLIPSE anthropogenic emissions. The model performs quite well over Alaska at background sites (e.g. Denali Park) compared to observations from the US Environmental Protection Agency (EPA). Discrepancies in modelled aerosols due to formation mechanisms and aerosol acidity are being investigated. Secondly, in order to better simulate Arctic aerosols and local pollution episodes, different schemes in WRF were tested over Alaska with a particular focus on improving simulations of the Arctic boundary layer structure and, in particular, wintertime temperature inversions which trap pollution at the ground. In order to simulate these extreme/cold meteorological conditions, different schemes linked to boundary layer physics, surface layer dynamics and the land surface have been tested and evaluated against Integrated Global Radiosonde Archive (IGRA2) and Integrated Surface Database (ISD). The model captures the cold meteorological conditions over Alaska, for example, capturing strong temperature inversions over Utqiagvik and Fairbanks in winter 2012.Thirdly, WRF-Chem is used to simulate background and local Arctic air pollution, using the improved WRF setup for meteorology over Alaska for winter 2013-2014. The model is being run with Hemispheric Transport of Air Pollution version 2 (HTAP v2) and other high-resolution emission inventories and evaluated against available aerosol data (PM2.5, black carbon, sulphate) over Alaska including data on aerosol chemical properties. The model is used to examine aerosol composition in locally produced and remote aerosols and to identify the origins contributing to aerosol distributions. The sensitivity of modelled aerosols to, for example, meteorological factors, such as humidity, is examined.

The role of polar regions increases in terms of megatrends such as globalization, new transport routes, demography and use of natural resources consequent effects of regional and transported pollutant concentrations. We set up the ERA-PLANET Strand 4 project iCUPE – integrative and Comprehensive Understanding on Polar Environments to provide novel insights and observational data on global grand challenges with an Arctic focus. We utilize an integrated approach combining in situ observations, satellite remote sensing Earth Observations (EO) and multi-scale modeling to synthesize data from comprehensive long-term measurements, intensive campaigns and satellites to deliver data products, metrics and indicators to the stakeholders concerning the environmental status, availability and extraction of natural resources in the polar areas. The iCUPE work consists of thematic state-of-the-art research and provision of novel data in atmospheric pollution, local sources and transboundary transport, characterization of arctic surfaces and their changes, assessment of concentrations and impacts of heavy metals and persistent organic pollutants and their cycling, quantification of emissions from natural resource extraction and validation and optimization of satellite Earth Observation (EO) data streams. In this paper we introduce the iCUPE project and summarize initial results arising out of integration of comprehensive in situ observations, satellite remote sensing and multiscale modeling in the Arctic context.

International audience

International audience

During the ACCESS airborne campaign in July 2012, extensive boreal forest fires resulted in significant aerosol transport to the Arctic. A 10-day episode combining intense biomass burning over Siberia and low-pressure systems over the Arctic Ocean resulted in efficient transport of plumes containing black carbon (BC) towards the Arctic, mostly in the upper troposphere (6–8 km). A combination of in situ observations (DLR Falcon aircraft), satellite analysis and WRF-Chem simulations is used to understand the vertical and horizontal transport mechanisms of BC with a focus on the role of wet removal. Between the northwestern Norwegian coast and the Svalbard archipelago, the Falcon aircraft sampled plumes with enhanced CO concentrations up to 200 ppbv and BC mixing ratios up to 25 ng kg−1. During transport to the Arctic region, a large fraction of BC particles are scavenged by two wet deposition processes, namely wet removal by large-scale precipitation and removal in wet convective updrafts, with both processes contributing almost equally to the total accumulated deposition of BC. Our results underline that applying a finer horizontal resolution (40 instead of 100 km) improves the model performance, as it significantly reduces the overestimation of BC levels observed at a coarser resolution in the mid-troposphere. According to the simulations at 40 km, the transport efficiency of BC (TEBC) in biomass burning plumes was larger (60 %), because it was impacted by small accumulated precipitation along trajectory (1 mm). In contrast TEBC was small (BC due to large-scale precipitation is responsible for a sharp meridional gradient in the distribution of BC concentrations. Wet removal in cumulus clouds is the cause of modeled vertical gradient of TEBC, especially in the mid-latitudes, reflecting the distribution of convective precipitation, but is dominated in the Arctic region by the large-scale wet removal associated with the formation of stratocumulus clouds in the planetary boundary layer (PBL) that produce frequent drizzle.

International audience; During the ACCESS airborne campaign in July 2012, extensive boreal forest fires resulted in significant aerosol transport to the Arctic. A 10 day episode combining intense biomass burning over Siberia and low-pressure systems over the Arctic Ocean resulted in efficient transport of plumes containing black carbon (BC) towards the Arctic, mostly in the upper troposphere. A combination of in situ airborne observations, satellite analysis and WRF- Chem simulations are used to understand the vertical and horizontal transport mechanisms of BC with a focus on the role of wet removal.During transport to the Arctic region, a large fraction of BC particles are scavenged by two wet deposition processes, namely wet removal by large-scale precipitation and removal in wet convective updrafts, with both processes contributing almost equally to the total accumulated deposition of BC. Our results underline that applying a finer horizontal resolution (40 vs 100km) improves the model performance, as it significantlyreduces the overestimation of BC levels observed at a coarser resolution in the mid- troposphere. According to the simulations at 40km, the transport efficiency of BC (TEBC) in biomass burning plumes is about 60%, which is impacted by small accumulated precipitation along trajectory (APT) (1mm). In contrast TEBC is very small (

Kinetic simulation results are presented for the interaction of spacecraft with space environment in low Earth orbit. Case studies are considered for DEMETER, for which small but distinctive potential variations have been measured on Instrument Champ Electrique (ICE) sensors, as the satellite goes through regions where the magnetic field B→ is nearly parallel to the satellite velocity v→. Our results point to a small variation in the potential of ICE probes under these conditions, but owing to the smallness of the signal and inherent statistical noise in our simulations, it is not possible to unambiguously explain observations. An earlier study of magnetic field effects on the Swarm electric field instrument is extended by computing Langmuir probe characteristics with and without a magnetic field. The possibility of probe crosstalk is also examined by comparing collected currents when the two probes have same and opposite bias voltages. Accounting for a representative ionospheric magnetic field is found to lead to appreciable quantitative differences in the probe characteristics. No significant crosstalk or mutual coupling is predicted between the probes under normal operation.

International audience; The Arctic is undergoing unprecedented changes as a result of rapid warming and socio- economic drivers. Even though the region is a receptor of anthropogenic pollution from the highly populated mid-latitudes, there are also local sources of pollution, such as shipping, that are already contributing to perturbing atmospheric composition. The Barents Sea, located off the northern coasts of Norway and Russia, has year-round shipping traffic and is likely to grow in a warming Arctic because of the economic benefits related to the opening up of the North-east passage placing it in a strategic position for the transport of goods from Europe to Asia. An increase in the marine traffic has already been observed over the past years in this region, resulting in increased emissions of pollutants.In this work, carried out as part of EU-FP7 project ICE-ARC (Ice, Climate, Economics - Arctic Research on Change), we study the contribution of the shipping emissions in the Barents Sea on atmospheric composition in the region for the high traffic summer period (July/August) using the regional chemistry-aerosol transport model WRF-Chem run at high resolution over the region. We examine impacts of shipping pollution on production of aerosols, in particular Secondary Organic Aerosol (SOA) and also on deposition (NO-, SO4 2-) of potentially important nutrients. The model is run using an analytical chemical mechanism for gas phase and aerosols (SAPRC99 coupled with VBS and MOSAIC) for present-day (2012) and future (2050) conditions with ECLIPSE anthropogenic emissions and Winter et al. (2014) shipping emissions. We take into account different future growth scenarios, such as CLE (current legislation) and HGS (high growth scenario), toinvestigate possible future changes in surface concentrations, total column burden and deposition fluxes. Potential chemistry-climate feedbacks are also examined such as those related to aerosol-cloud interactions or changes in photolysis rates due to shipping.

In the future, a plasma contactor using a hollow cathode will be applied to charging mitigation of large structures and electron emitter/collector of electrodynamic tether systems in space. In this study, ground-based experiments on the plasma contactor were carried out to examine basic operational characteristics. In electron emission, the same operational performance as that only with a simple assembly of the hollow cathode was obtained in the simulating low-earth-orbit (LEO) plasma. In electron collection, the excellent effect of collection current enhanced in the simulating LEO plasma existed. Furthermore, the mechanism of electron collection by the plasma contactor was examined from plasma parameter distributions near the plasma contactor. As a result, an intensive interaction between the contactor plasma and the simulating LEO plasma was observed.

Bare-tether systems are one of the greatest-efficiency electrodynamic tethered systems. The system with an uninsulated portion of the metallic tether itself to collect electrons from the space plasma is operated as a thruster or a power generator on a satellite. Ground experiments were carried out to understand the phenomenon of electron collection by a bare tether in space. Metallic tether samples were exposed to a simulating low-Earth-Orbit plasma flow as varying tether sample diameter and length, and plasma velocity. A magnetic field was also applied. The normalized collection current increased with plasma velocity. The existence of magnetic field increased the normalized collection current because of the edge effect of a tether sample or the three-dimensional effect. A high collection current above the orbital-motion-limited current could be achieved with a magnetic field. The current characteristics of a bare tether strongly depended on the plasma velocity and surrounding magnetic field.

International audience; DEMETER was a low Earth orbiting microsatellite in operation between July 2004 and December 2010. Its scientific objective was the study of ionospheric perturbations in relation to seismic activity and man-made activities. Its payload was designed to measure electromagnetic waves over a large frequency range as well as ionospheric plasma parameters (electron and ion densities, fluxes of energetic charged particles). This paper will show both expected and unusual events recorded by the satellite when it was in operation. These latter events have been selected from the DEMETER database because they are rare or even have never been observed before, because they have a very high intensity, or because they are related to abnormalities of the experiments under particular plasma conditions. Some events are related to man-made radio waves emitted by VLF ground-based transmitters or power line harmonic radiation. Natural waves, such as atypical quasi-periodic emissions or uncommon whistlers, are also shown.

In this paper, we report initial results from a detailed statistical study of the plasma waves observed by the DEMETER satellite over the Sichuan region during a period of 20 days encompassing the large earthquake of magnitude M =7.9 that occurred on 12 May 2008. The main objective of this paper is to present a statistical method to process and analyze plasma wave data and assist in detecting possible earthquake precursors among larger irregular disturbances arising from the natural variability of the ionized environment of the Earth. This method, presently used for dayside observations, involves two stages. First, VLF wave spectra are processed to recognize the various types of plasma waves usually observed at mid and low latitudes and derive a reduced number of parameters that fully characterize these emissions and may be conveniently used for a detailed statistical study. In a second stage, we perform a statistical analysis of the results by taking into account two "reference zones" displaced respectively 30° eastward and westward from the "epicentre zone". Plasma and wave disturbances possibly induced by earthquakes in preparation are likely to maximize close to the "epicentre zone", while natural disturbances associated, in particular, with the varying magnetic activity are rather uniform over a wider longitude sector, thus enabling the use of observations over the reference zones as a base line. The initial results of this study show a deviation of the power spectrum of electrostatic turbulence in the epicentre zone about 6 days prior to the earthquake but no significant anomalous variations can be observed on other characteristics of plasma waves. From the analysis of the data over the two reference~zones and using recently produced sector magnetic activity indices, we conclude that the enhancement of electrostatic turbulence is associated with magnetospheric processes rather than with pre-seismic activity.

International audience; Two of the main scientific objectives of the DEMETER mission concerned the search for ionospheric effects due to earthquakes and the study of disturbances associated with human activities or natural phenomena such as thunderstorms. The large data base gathered during nearly 6 years of in-orbit operation has lead to making new observations and/or to improving the understanding of several, already identified, phenomena. The main effects of human activities are observed in the field of radio-electric emissions and we present several results on the EM waves generated by power networks or associated with high power VLF transmitters. The search for ionospheric disturbances associated with earthquakes relies on thorough statistical studies to disentangle seismic effects from the variations induced by the physical processes that control the ionospheric plasma and natural emissions. Several studies are presented, and one of them has demonstrated a decrease of the ELF wave intensity in the frequency range between 1 and 2 kHz a few hours before the shock.

International audience; We present simultaneous observations of daytime medium-scale traveling ionospheric disturbances (MSTIDs) over North America, using measurements of the Total Electron Content (TEC) by the US GPS network and ionospheric plasma data from the DEMETER micro-satellite. Several events show latitudinal variations of the plasma parameters at satellite altitude corresponding to the MSTID structures revealed on 2D TEC maps. In a case study with a very well defined MSTID, quasi periodic variations of the plasma density and of the ion velocity parallel to the Earth's magnetic field are observed along the satellite orbit that match the signature of the MSTID on the TEC maps. We believe it is the first simultaneous observation of parallel plasma motion in the topside ionosphere and propagating MSTID structures in the F-region. An initial analysis of this event is performed in the light of results from simple model of ionospheric disturbances associated with Atmospheric Gravity Waves (AGWs).

Background and objective: Oral zolmitriptan is highly effective in the acute treatment of migraine. However, nausea and vomiting during attacks may limit the usefulness of oral medications. An alternative, nasal spray, formulation has been developed that demonstrates good efficacy, high tolerability and a very fast onset of action. This study assessed the pharmacokinetics and bioavailability of zolmitriptan and its active metabolite 183C91 in healthy Japanese subjects following single-dose (2.5 or 5mg) oral or intranasal administration. Methods: This was a single-centre, open-label, randomised, crossover study. Forty-eight subjects each received one oral and one intranasal dose of 2.5 or 5mg zolmitriptan, with a 72-hour washout period between doses. Blood was drawn at various timepoints from 2 minutes to 15 hours post-dose and urine was collected over the course of the study; samples were analysed for zolmitriptan and 183C91, from which pharmacokinetic parameters were calculated. Results: Zolmitriptan was detected in plasma 2 minutes after intranasal administration in the majority of subjects (∼75%) compared with 10 minutes after oral administration. The intranasal : tablet ratio for zolmitriptan area under the concentration-time curve from time zero to infinity was 0.924 (90% CI 0.826, 1.033) and 0.960 (90% CI 0.865, 1.066) for the 2.5 and 5mg doses, respectively. Other pharmacokinetic parameters were similar between the two formulations. While 183C91 appeared in the plasma concurrently to zolmitriptan after oral dosing, its appearance was delayed to approximately 30 minutes after intranasal dosing. Zolmitriptan was safe and well tolerated at both doses. Conclusions: The rapid absorption of zolmitriptan nasal spray may explain the faster relief from migraine reported in patients compared with oral zolmitriptan.

A full three dimensional Navier-Stokes solver elsA developed by ONERA is used to design and study the aerothermodynamics of a MEMS-based micro turbine. This work is performed in the framework of micro turbomachinery project at ONERA. A few millimeter scale micro turbine is operated in a low Reynolds number regime (Re = 5,000∼50,000), which implies a more important influence of skin friction and heat transfer than the conventional large-scale gas turbine. The 2D geometry constraints due to the limitation of fabrication technology also distinguish the aerothermodynamic characteristics of a micro turbine from that of conventional turbomachinery. Thus, for the foundation of aerothermodynamic design of micro turbomachinery, understanding of low Reynolds number effects on the performance is required and then the design of the turbine geometry can be optimized. In this study, aero-thermodynamic effects at low Reynolds number and different stator/rotor configurations are examined with a prescribed wall temperature. Losses due to heat transfer to walls and skin friction are estimated and their effects on the operating performance are discussed. Power delivery to turbine blades is checked and found satisfactory to give the objective design value of more than 100W. The effects of turbine exhaust geometry and the number of blades on turbine performance are also discussed.Copyright © 2005 by ASME

An electrodynamic bare tether has been considered as an alternative method of propulsion without expenditure of propellant. The object of the work reported here is the development of a numerical method, Particle-In-Cell (PIC) method, for the calculation of electron current to a positive bare tether moving at orbital velocity in the ionosphere, i.e. in a flowing magnetized plasma under Maxwellian collisionless conditions. In a PIC code, a number of particles are distributed in phase space and the computational domain has a grid on which the Poisson equation is solved for field quantities. The code uses the quasi-neutrality condition to solve for the local potential at points in the plasma which coincide with the computational outside boundary. Given the boundary conditions, Poisson equations is solved in such a way that the presheath region can be captured in the computation. Electrons are assumed to have a Maxwellian distribution at the boundary due to their high mobility, whereas ions are assumed so only...

The Arctic is undergoing very rapid changes, such as decreasing sea-ice extent during summer. As a result, transit shipping via the Northern Sea Route, along the northern coast of Scandinavia and Russia, is already occurring. As shipping through the Arctic increases, emissions of air pollutants (aerosols, ozone, and their precursors) into the lower troposphere are likely to become more significant. In addition to shipping, emissions linked to extraction of Arctic oil/gas deposits and associated infrastructure will also increase. As part of the EU ACCESS project, we investigate the role of current and future anthropogenic activities in the Arctic on regional air pollution and the concentrations of short-lived climate forcing agents in the Arctic troposphere using a regional chemical transport model. The model simulates emissions, transport, mixing, and chemical transformation of trace gases and aerosols simultaneously with the meteorology. The model is used to examine ozone and aerosol formation in fresh and aged plumes. The sensitivity of results to model resolution is also examined. Results are also used to quantify the impacts of ship and oil/gas emissions on regional scales in the Arctic. Model results will be discussed in the context of a DLR aircraft campaign in July 2012, based in northern Norway, to investigate emissions from Arctic shipping and oil/gas extraction (including measurements of trace gases and aerosols).

International audience