51 research outputs found
Complexation of Lysozyme with Adsorbed PtBS-b-SCPI Block Polyelectrolyte Micelles on Silver Surface
We present a study of the interaction of the positively charged model protein lysozyme with the negatively charged amphiphilic diblock polyelectrolyte micelles of poly(tert-butylstyrene)-bsodium (sulfamate/carboxylate)isoprene) (PtBS-b-SCPI) on the surface of silver. The adsorption kinetics are monitored by surface plasmon resonance and the surface morphology by atomic force microscopy. The micellar adsorption kinetics is dictated by two processes and the micellar layer morphology shows that the micelles do not lose their integrity upon adsorption. The complexation of lysozyme with the adsorbed micellar layers depends on the micelles arrangement and density in the underlying layer and lysozyme follows the local morphology of the underlying roughness. When the micellar adsorbed amount is small, the layers show low capacity in protein binding and low resistance in loading. When the micellar adsorbed amount is high the situation is inversed. The adsorbed layers both with or without added protein are found to be irreversibly adsorbed on the Ag surface
Two-dimensional mineral dust radiative effect calculations from CALIPSO observations over Europe
A demonstration study to examine the feasibility of retrieving dust radiative effects based on combined satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer), CERES (Clouds and the Earth's Radiant Energy System) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar vertical profiles along their orbit is presented. The GAME (Global Atmospheric Model) radiative transfer model is used to estimate the shortwave and longwave dust radiative effects below the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) orbit assuming an aerosol parameterization based on the CALIOP vertical distribution at a horizontal resolution of 5Âżkm and additional AERONET (Aerosol Robotic Network) data. Two study cases are analyzed: a strong long-range transport mineral dust event (aerosol optical depth, AOD, of 0.52) that originated in the Sahara Desert and reached the United Kingdom and a weaker event (AODÂż=Âż0.16) that affected eastern Europe. The radiative fluxes obtained are first validated in terms of radiative efficiency at a single point with spaceâtime colocated lidar ground-based measurements from EARLINET (European Aerosol Research Lidar Network) stations below the orbit. The methodology is then applied to the full orbit. The strong dependence of the radiative effects on the aerosol load (and to a lesser extent on the surface albedo) highlights the need for accurate AOD measurements for radiative studies. The calculated dust radiative effects and heating rates below the orbits are in good agreement with previous studies of mineral dust, with the radiative efficiency obtained at the surface ranging between -80.3 and -63.0ÂżWÂżm-2 for lower dust concentration event and -119.1 and -79.3ÂżWÂżm-2 for the strong event. Thus, results demonstrate the validity of the method presented here to retrieve 2-D accurate radiative properties with large spatial and temporal coverage.Peer ReviewedPostprint (published version
Airportsâ Crisis Management Processes and Stakeholders Involved
Airports are exposed to various physical incidents that can be classified as aviation and non-aviation related incidents, including terrorist attacks, bombings, natural disasters (e.g. earthquake or tsunami and man-made disasters such as terrorist attacks) etc. (Kanyi, Kamau, & Mireri, 2016). In addition to this, cyber-attacks to airport operations are emerging especially with the increasing use of Information Systems (IS), such as electronic tags for baggage handling and tracking, remote check-in, smart boarding gates, faster and more reliable security screening technologies and biometric immigration controls etc. Any physical or cyber incident that causes loss of infrastructure or massive patient surge, such as natural disasters, terrorist acts, or chemical, biological, radiological, nuclear, or explosive hazards could affect the airportsâ services provision and could cause overwhelming pressure. During the crisis management, several stakeholders that have different needs and requirements, get involved in the process, trying to cooperate, respond and support recovery and impact mitigation. The aim of this paper is to present a holistic security agenda that defines the stakeholders involved in the respective processes followed during the crisis management cycle. This agenda is based both on normative literature, such as relevant standards, guidelines, and practices and on knowledge and feedback extrapolated from a case study conducted in the context of the SATIE project (H2020-GA832969). In meeting paperâs aim, initially the normative review of the phases of the crisis management cycle (preparedness, response, recovery and mitigation) in the context of airports as well as general practices applied, are presented. Moreover, the key airport stakeholders and operation centres involved in airports operations, as well as during the crisis management are analysed. By combining the information collected, a holistic cyber and physical crisis management cycle including the stakeholders and the relevant processes are proposed. The crisis management process is taken into consideration into the SATIE project, which aims to build a security toolkit in order to protect critical air transport infrastructures against combined cyber-physical threats. This toolkit will rely on a complete set of semantic rules that will improve the interoperability between existing systems and enhanced security solutions, in order to ensure more efficient threat prevention, threat and anomaly detection, incident response and impact mitigation, across infrastructures, populations and environment.</p
EUNADICS-AV early warning system dedicated to supporting aviation in the case of a crisis from natural airborne hazards and radionuclide clouds
The purpose of the EUNADICS-AV (European Natural Airborne Disaster Information and Coordination System for Aviation) prototype early warning system (EWS) is to develop the combined use of harmonised data products from satellite, ground-based and in situ instruments to produce alerts of airborne hazards (volcanic, dust, smoke and radionuclide clouds), satisfying the requirement of aviation air traffic management (ATM) stakeholders (https://cordis.europa.eu/project/id/723986, last access: 5 November 2021). The alert products developed by the EUNADICS-AV EWS, i.e. near-real-time (NRT) observations, email notifications and netCDF (Network Common Data Form) alert data products (called NCAP files), have shown significant interest in using selective detection of natural airborne hazards from polar-orbiting satellites. The combination of several sensors inside a single global system demonstrates the advantage of using a triggered approach to obtain selective detection from observations, which cannot initially discriminate the different aerosol types. Satellite products from hyperspectral ultravioletâvisible (UVâvis) and infrared (IR) sensors (e.g. TROPOMI â TROPOspheric Monitoring Instrument â and IASI â Infrared Atmospheric Sounding Interferometer) and a broadband geostationary imager (Spinning Enhanced Visible and InfraRed Imager; SEVIRI) and retrievals from ground-based networks (e.g. EARLINET â European Aerosol Research Lidar Network, E-PROFILE and the regional network from volcano observatories) are combined by our system to create tailored alert products (e.g. selective ash detection, SO2 column and plume height, dust cloud, and smoke from wildfires). A total of 23 different alert products are implemented, using 1 geostationary and 13 polar-orbiting satellite platforms, 3 external existing service, and 2 EU and 2 regional ground-based networks. This allows for the identification and the tracking of extreme events. The EUNADICS-AV EWS has also shown the need to implement a future relay of radiological data (gamma dose rate and radionuclides concentrations in ground-level air) in the case of a nuclear accident. This highlights the interest of operating early warnings with the use of a homogenised dataset. For the four types of airborne hazard, the EUNADICS-AV EWS has demonstrated its capability to provide NRT alert data products to trigger data assimilation and dispersion modelling providing forecasts and inverse modelling for source term estimate. Not all of our alert data products (NCAP files) are publicly disseminated. Access to our alert products is currently restricted to key users (i.e. Volcanic Ash Advisory Centres, national meteorological services, the World Meteorological Organization, governments, volcano observatories and research collaborators), as these are considered pre-decisional products. On the other hand, thanks to the EUNADICS-AVâSACS (Support to Aviation Control Service) web interface (https://sacs.aeronomie.be, last access: 5 November 2021), the main part of the satellite observations used by the EUNADICS-AV EWS is shown in NRT, with public email notification of volcanic emission and delivery of tailored images and NCAP files. All of the ATM stakeholders (e.g. pilots, airlines and passengers) can access these alert products through this free channel.Peer ReviewedArticle escrit per 46 autors/es: Hugues Brenot Nicolas Theys Lieven Clarisse Jeroen van Gent Daniel Hurtmans Sophie Vandenbussche Nikolaos Papagiannopoulos Lucia Mona Timo Virtanen Andreas Uppstu Mikhail Sofiev Luca Bugliaro Margarita VĂĄzquez-Navarro Pascal Hedelt Michelle Maree Parks Sara Barsotti Mauro Coltelli William Moreland Simona Scollo Giuseppe Salerno Delia Arnold-Arias Marcus Hirtl Tuomas Peltonen Juhani Lahtinen Klaus Sievers Florian Lipok Rolf RĂŒfenacht Alexander Haefele Maxime Hervo Saskia Wagenaar Wim Som de Cerff Jos de Laat Arnoud Apituley Piet Stammes Quentin Laffineur Andy Delcloo Robertson Lennart Carl-Herbert Rokitansky Arturo Vargas Markus Kerschbaum Christian Resch Raimund Zopp Matthieu Plu 1 Vincent-Henri Peuch Michel van Roozendael Gerhard WotawaPostprint (author's final draft
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Looking into CALIPSO climatological products: Evaluation and suggestions from EARLINET
CALIPSO (Cloud-Aerosol Lidar and Pathfinder Satellite Observations) Level 3 (CL3) data were compared against EARLINET (European Aerosol Research Lidar Network) monthly averages obtained by profiles during satellite overpasses. Data from EARLINET stations of Ăvora, Granada, Leipzig, Naples and Potenza, equipped with advanced multi-wavelength Raman lidars were used for this study. Owing to spatial and temporal differences, we reproduced the CL3 filtering rubric onto the CALIPSO Level 2 data. The CALIPSO monthly mean profiles following this approach are called CALIPSO Level 3*, CL3*. This offers the possibility to achieve direct comparable datasets. In respect to CL3 data, the agreement typically improved, in particular above the areas directly affected by the anthropogenic activities within the planetary boundary layer. However in most of the cases a subtle CALIPSO underestimation was observed with an average bias of 0.03 km-1. We investigated the backscatter coefficient applying the same screening criteria, where the mean relative difference in respect to the extinction comparison improved from 15.2% to 11.4%. Lastly, the typing capabilities of CALIPSO were assessed outlining the importance of the correct aerosol type (and associated lidar ratio value) assessment to the CALIPSO aerosol properties retrieval
An automatic aerosol classification for earlinet: application and results
Aerosol typing is essential for understanding the impact of the different aerosol sources on climate, weather system and air quality. An aerosol classification method for EARLINET (European Aerosol Research Lidar Network) measurements is introduced which makes use the Mahalanobis distance classifier. The performance of the automatic classification is tested against manually classified EARLINET data. Results of the application of the method to an extensive aerosol dataset will be presented. © The Authors, published by EDP Sciences, 2018.Peer ReviewedPostprint (published version
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An EARLINET early warning system for atmospheric aerosol aviation hazards
A stand-alone lidar-based method for detecting airborne hazards for aviation in near real time (NRT) is presented. A polarization lidar allows for the identification of irregular-shaped particles such as volcanic dust and desert dust. The Single Calculus Chain (SCC) of the European Aerosol Research Lidar Network (EARLINET) delivers high-resolution preprocessed data: the calibrated total attenuated backscatter and the calibrated volume linear depolarization ratio time series. From these calibrated lidar signals, the particle backscatter coefficient and the particle depolarization ratio can be derived in temporally high resolution and thus provide the basis of the NRT early warning system (EWS). In particular, an iterative method for the retrieval of the particle backscatter is implemented. This improved capability was designed as a pilot that will produce alerts for imminent threats for aviation. The method is applied to data during two diverse aerosol scenarios: first, a record breaking desert dust intrusion in March 2018 over Finokalia, Greece, and, second, an intrusion of volcanic particles originating from Mount Etna, Italy, in June 2019 over Antikythera, Greece. Additionally, a devoted observational period including several EARLINET lidar systems demonstrates the network's preparedness to offer insight into natural hazards that affect the aviation sector. © 2020 Author(s)
An EARLINET early warning system for atmospheric aerosol aviation hazards
A stand-alone lidar-based method for detecting
airborne hazards for aviation in near real time (NRT) is
presented. A polarization lidar allows for the identification
of irregular-shaped particles such as volcanic dust and
desert dust. The Single Calculus Chain (SCC) of the European
Aerosol Research Lidar Network (EARLINET) delivers
high-resolution preprocessed data: the calibrated total
attenuated backscatter and the calibrated volume linear
depolarization ratio time series. From these calibrated lidar
signals, the particle backscatter coefficient and the particle
depolarization ratio can be derived in temporally high resolution
and thus provide the basis of the NRT early warning
system (EWS). In particular, an iterative method for the retrieval
of the particle backscatter is implemented. This improved
capability was designed as a pilot that will produce alerts for imminent threats for aviation. The method is applied
to data during two diverse aerosol scenarios: first, a
record breaking desert dust intrusion in March 2018 over Finokalia,
Greece, and, second, an intrusion of volcanic particles
originating from Mount Etna, Italy, in June 2019 over
Antikythera, Greece. Additionally, a devoted observational
period including several EARLINET lidar systems demonstrates
the networkâs preparedness to offer insight into natural
hazards that affect the aviation sector.ACTRIS-2
654109ACTRIS preparatory phase
739530EUNADICS-AV
723986E-shape (EuroGEOSS Showcases: Applications Powered by Europe)
820852Ministry of Research and Innovation, Ontario
19PFE/17.10.2018Romanian National Core Program
18N/2019European Commission
European Commission Joint Research Centre
72569
Observing mineral dust in northern Africa, the middle east and Europe: current capabilities and challenges ahead for the development of dust services
Mineral dust produced by wind erosion of arid and semi-arid surfaces is a major
component of atmospheric aerosol that affects climate, weather, ecosystems, and
socio-economic sectors such as human health, transportation, solar energy, and air
quality. Understanding these effects and ultimately improving the resilience of affected
countries requires a reliable, dense, and diverse set of dust observations, fundamental
for the development and the provision of skillful dust forecasts tailored products. The
last decade has seen a notable improvement of dust observational capabilities in terms
of considered parameters, geographical coverage, and delivery times, as well as of
tailored products of interest to both the scientific community and the various end-users.
Given this progress, here we review the current state of observational capabilities
including in-situ, ground-based and satellite remote sensing observations, in Northern
Africa, the Middle East and Europe for the provision of dust information considering
the needs of various users. We also critically discuss observational gaps and related
unresolved questions while providing suggestions for overcoming the current
limitations. Our review aims to be a milestone for discussing dust observational gaps
at a global level to address the needs of users, from research communities to nonscientific stakeholders
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EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product
We present the evaluation activity of the European Aerosol Research Lidar Network (EARLINET) for the quantitative assessment of the Level 2 aerosol backscatter coefficient product derived by the Cloud-Aerosol Transport System (CATS) aboard the International Space Station (ISS; Rodier et al., 2015). The study employs correlative CATS and EARLINET backscatter measurements within a 50km distance between the ground station and the ISS overpass and as close in time as possible, typically with the starting time or stopping time of the EARLINET performed measurement time window within 90min of the ISS overpass, for the period from February 2015 to September 2016. The results demonstrate the good agreement of the CATS Level 2 backscatter coefficient and EARLINET. Three ISS overpasses close to the EARLINET stations of Leipzig, Germany; Ăvora, Portugal; and Dushanbe, Tajikistan, are analyzed here to demonstrate the performance of the CATS lidar system under different conditions. The results show that under cloud-free, relative homogeneous aerosol conditions, CATS is in good agreement with EARLINET, independent of daytime and nighttime conditions. CATS low negative biases are observed, partially attributed to the deficiency of lidar systems to detect tenuous aerosol layers of backscatter signal below the minimum detection thresholds; these are biases which may lead to systematic deviations and slight underestimations of the total aerosol optical depth (AOD) in climate studies. In addition, CATS misclassification of aerosol layers as clouds, and vice versa, in cases of coexistent and/or adjacent aerosol and cloud features, occasionally leads to non-representative, unrealistic, and cloud-contaminated aerosol profiles. Regarding solar illumination conditions, low negative biases in CATS backscatter coefficient profiles, of the order of 6.1%, indicate the good nighttime performance of CATS. During daytime, a reduced signal-to-noise ratio by solar background illumination prevents retrievals of weakly scattering atmospheric layers that would otherwise be detectable during nighttime, leading to higher negative biases, of the order of 22.3%. © Author(s) 2019
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