Publikace

informace pocházejí z univerzitní databáze V3S

Autoři:
doc. Ing. Jakub Hospodka, Ph.D.; Rosenow, J.; Fricke, H.; Ing. Bc. Sébastien Lán, Ph.D.
Publikováno:
2023, SUSTAINABILITY, 15 (11), ISSN 2071-1050
Anotace:
In an industry beset by economic and environmental crises, air transport, the safest and most efficient long-haul mode of transport, is confronted daily with multi-criteria challenges to improve its environmental performance. The formation of contrails through the emission of water vapor and condensation nuclei in what are actually dry and clean atmospheric layers represents one of the most unpredictable, or measurable, environmental impacts of air traffic. Following the bottom-up principle to evaluate individual contrails in order to derive recommendations for trajectory optimization, not only the calculation of the radiative forcing of the contrails but also the modeling of their life cycle is burdened with uncertainties. In former studies for modeling the microphysical life cycle of contrails based on a 3-D Gaussian plume model, the atmospheric conditions, specifically the turbulence, were often unknown and had to be considered as a free input variable. In this study, an innovative photographic method for identifying and tracking contrails in Central Europe, connected with database access to Automatic Dependent Surveillance-Broadcast (ADS-B) data (i.e., aircraft type, speed, altitude, track, etc.), and a combination of measured and modeled weather data are used to validate the contrail life-cycle model (i.e., the assumed Gaussian plume behavior). We found that it is challenging to model the position of ice-supersaturated layers with global forecast models, but they have the most significant impact on the contrail lifetime. On average, the contrail's lifespan could be modeled with an error margin of 10%. Sometimes, we slightly underestimated the lifetime. With the validated and plausible contrail life-cycle model, we can apply the climate effectiveness of individual contrails with higher certainty in trajectory optimization and compare it, for example, with economic aspects such as delay costs or fuel costs.
DOI:
Typ:
Článek v periodiku excerpovaném SCI Expanded

Autoři:
Ing. Bc. Sébastien Lán, Ph.D.; doc. Ing. Jakub Hospodka, Ph.D.
Publikováno:
2022, Sustainability — Open Access Journal, 14 (23), ISSN 2071-1050
Anotace:
The impact of contrails on Earth’s climate is probably not negligible, yet there are only a few initiatives aimed at mitigating the influence of aviation on the environment. To achieve zero CO2 emissions, aircraft manufacturers and airlines propose complex and costly methods and technologies such as synthetic fuels, hybrid engines, or expensive carbon offsetting. On the other hand, contrail mitigation by achievable operational measures has the potential to achieve benefits with a very positive cost-benefit ratio without the need for a complex technological change in aviation. It seems that one suitable tool for contrail mitigation is the change in flight level. Therefore, we focused on the assessment of flight levels with typical contrails occurrence and common flight levels used by air traffic management. Some influence of tropopause height throughout the year was presumed to be a factor, therefore we studied different times of the year. The tropopause height influences not only contrail occurrence but also the preferred flight level, as airlines tend to avoid flying directly in the tropopause. We present some basic statistics about the frequency of contrail occurrence based on flight level. We focused on long-lived contrails to emphasize the more important contrails in this context. Information about flight levels is based on ADS-B data transmitted by aircraft and recorded on a ground station near the place of contrail occurrence, which was based on optical survey.
DOI:
Typ:
Článek v periodiku excerpovaném SCI Expanded

Autoři:
Ing. Peter Olexa; Ing. Miroslav Špák, Ph.D.; Ing. Slobodan Stojić, Ph.D.; Ing. Bc. Sébastien Lán, Ph.D.; Ing. Marek Hamza
Publikováno:
2022, 2022 New Trends in Civil Aviation (NTCA), Praha, České vysoké učení technické v Praze), p. 141-146), ISBN 978-80-01-06985-1, ISSN 2694-7854
Anotace:
This paper describes the elaboration of Enhanced diversion airport selection methodology, which can be used for the optimization of flight planning by airline operators and the better diversion decisions in the real time operations. The paper is based on the analysis of the problematics of flight diversion from different perspectives and determining the factors influencing the diversion recovery. Based on these factors an methodology is proposed for decision making in the process of alternate airports selection during the planning process and real time operations. The selection methodology incorporates operational and commercial factors determining the suitability of an airport as an alternate destination. Emphasis is put on the economic suitability of the airport in terms of minimizing costs in case of flight diversion. In the validation process the methodology was applied on selected airports using real data and compared with actual operations, and as such presented to the experts. The result of the work is an optimized system for selecting an alternate airport in case of diversion from the destination, with the possibility of wider application and further elaboration when using the real-time shared data.
DOI:
Typ:
Stať ve sborníku z prestižní konf.

Autoři:
Ing. Bc. Sébastien Lán, Ph.D.; Ing. Miroslav Špák, Ph.D.
Publikováno:
2020, Transportation Research Procedia, Linz, Elsevier BV), p. 225-231), ISSN 2352-1465
Anotace:
Contrail is an artificial cloud composed of ice crystals which forms behind jet aircraft at upper troposphere and lower stratosphere. The formation is caused by increase in the relative humidity in the engine plume due to water vapor emissions and by low ambient temperatures. According to the Schmidt-Appleman criterion contrail forms if the humidity reaches liquid saturation. It depends on the state of atmosphere in terms of relative humidity and ambient pressure. This article is focused on contrail formation conditions at high altitudes in the Czech airspace. It analyses the vertical profile of the atmosphere and suitable conditions for contrail formation at different flight levels during the year. Meteorological data was obtained from aerological measurement and used for the assessment of contrail formation for typical jet aircraft.
DOI:
Typ:
Stať ve sborníku z prestižní konf. (Scopus)

Autoři:
Ing. Bc. Sébastien Lán, Ph.D.; Ing. Miroslav Špák, Ph.D.
Publikováno:
2019, TRANSPORT MEANS 2019 - PROCEEDINGS OF THE 23rd INTERNATIONAL SCIENTIFIC CONFERENCE, Kaunas, Kaunas University of Technology), p. 1559-1563), ISSN 1822-296X
Anotace:
Condensation trail or simply contrail is an artificial cloud which forms behind aircraft and initially looks like a white strip. It may dissipate very quickly but it may also spread and persist for minutes or even couple of hours. The increase in cloudiness coverage has a negative impact on the climate because it changes the radiation balance of the Earth-atmosphere system. Contrails and contrail induced cloudiness cause mostly positive radiative forcing which tends to warm the atmosphere. This article is mainly focused on contrail formation. It explains the basic principle of contrail and contrail induced cloudiness formation and shows the possible way to calculate whether a contrail will or will not develop under given conditions. The paper briefly describes an ongoing contrail research carried out by the Czech Technical University in Prague as well. One part of the research is focused on ground-based contrail observation and measurement. Meteorological data which is necessary for contrail formation prediction are retrieved from aerological measurement. The aim of the whole research is to identify conditions under which it would be better to prevent contrail formation and subsequently define operations measures to avoid contrail formation.
Typ:
Stať ve sborníku z prestižní konf. (Scopus)

Autoři:
Vidoň, V.; Ing. Bc. Sébastien Lán, Ph.D.
Publikováno:
2019, MAD - Magazine of Aviation Development, 7 (3), p. 15-20), ISSN 1805-7578
Anotace:
This article describes the causes and behavior of aircraft condensation trails, aircraft radar technology, communication between aircraft and ground control stations, description of the function, analysis and processing of the ADS-B receivers and registers data. It also deals with the design and creation of a suitable web application with a simple user interface and a database for storing and processing this data. The work was based mainly on academical materials and sources, focusing on the issue of condensation trails, ADS-B functionality and programming of web applications.
DOI:
Typ:
Článek v odborném recenzovaném periodiku cizojazyčně

Autoři:
Ing. Bc. Sébastien Lán, Ph.D.; Ing. Tereza Topková, Ph.D.; Mgr. Iveta Kameníková, Ph.D.
Publikováno:
2018, Young Transportation Engineers Conference 2018, Praha, Fakulta dopravní), ISBN 978-80-01-06464-1
Anotace:
Contrails are line-shaped clouds formed behind aircraft which may persist for hours while growing to resemble cirrus clouds. Contrails cause positive radiative forcing which tends to warm the atmosphere. This paper describes the contrail formation, climate effect and contrail research carried out by the Department of Air Transport, Faculty of Transportation Sciences, Czech Technical University in Prague. The research is based on contrail observation, ADS-B messages, Mode S messages and aerological measurement. The aim of the research is to identify the frequency of contrail occurrence, their lifetime and other properties and compare them to meteorological conditions.
Typ:
Stať ve sborníku z mezinár. konf. cizojazyčně