Yazar "Erdogan, M. A." seçeneğine göre listele
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Öğe Astronomical site selection for Antarctica with astro-meteorological parameters(Springer, 2024) Aksaker, N.; Bayazit, M.; Kurt, Z.; Yerli, S. K.; Aktay, A.; Erdogan, M. A.The primary objective of this study is to employ Multi-Criteria Decision Analysis (MCDA) and Geographical Information System (GIS) techniques to identify and assess potential sites for astronomical observations in Antarctica. Our study focuses on the development of the Suitability Index for Astronomical Sites in Antarctica (SIASA). This index is formulated by merging data from satellites and models, providing extensive temporal and spatial coverage over two decades. To assess its suitability, we employed a combination of MCDA and GIS techniques, allowing us to evaluate various data, including cloud cover (CC), precipitable water vapor (PWV) levels, elevation, atmospheric temperature and wind speed. Our analysis confirmed the exceptional characteristics of Antarctica: An average of 361 cloud-free days per year, exceptionally low PWV values (0 mm), and an average elevation of 2.300 meters. The stable atmospheric wind profile further enhances its suitability for astronomical observations. Long-term trends and correlations of the data were also studied. SIASA values identified the eastern and inner parts of the Transatlantic Mountains as highly favorable for astronomical observations, while the coastal areas were considered less suitable. The best sites cover 10% of Antarctica in all SIASA scenarios, with Dome A, Ridge A and Dome F having the highest values of all stations. These findings hold considerable importance in planning future astronomical sites on the continent.Öğe A case study of light pollution in France(Springer, 2020) Aksaker, N.; Yerli, S. K.; Kurt, Z.; Bayazit, M.; Aktay, A.; Erdogan, M. A.In this study, we investigate the effects of light pollution in France using GIS data which was first used in Aksaker et al. (Mon. Not. R. Astron. Soc. 493:1204, 2020) (so called astroGIS database - astrogis.org). A subset of Artificial Light layer of astroGIS database has been adapted for years between January 2012 and December 2019. During 2019, half a million of lumen has been released into space from the total surface area of France. Annual light pollution in France has a decreasing trend. France continues to have potential Dark Sky Park locations for example cities like Cantal, Lot, Lozere and Creuse having the lowest light pollution values. Light pollution is strongly correlated with population (R-2 similar or equal to 0.85) and GDP (R-2 similar or equal to 0.84). In addition, half of the observatories remain under the light polluted areas.Öğe Global Site Selection for Astronomy(Oxford Univ Press, 2020) Aksaker, N.; Yerli, S. K.; Erdogan, M. A.; Kurt, Z.; Kaba, K.; Bayazit, M.; Yesilyaprak, C.A global site selection for astronomy was performed with 1 km spatial resolution (similar to 1 gigapixel in size) using long-term and up-to-date datasets to classify the entire terrestrial surface of the Earth. Satellite instruments are used to get the following datasets of geographical information system (GIS) layers: cloud coverage, digital elevation model, artificial light, precipitable water vapour, aerosol optical depth, wind speed, and land use and land cover. A multi-criteria decision analysis (MCDA) technique is applied to these datasets, creating four different series where each layer will have a specific weight. We introduce for the first time a suitability index for astronomical sites (SIAS). This index can be used to find suitable locations and to compare different sites or observatories. The midwestern Andes in South America and the Tibetan Plateau in western China were found to be the best in all SIAS series. Considering all the series, less than 3 per cent of all terrestrial surfaces are found to be the best regions to establish an astronomical observatory. In addition to this, only approximately 10 per cent of all current observatories are located in good locations in all SIAS series. Amateurs, institutions or countries aiming to construct an observatory could create a shortlist of potential site locations using a layout of SIAS values for each country without spending time and budget. The outcomes and datasets of this study have been made available through a website, the Astro GIS Database, at www.astrogis.org.Öğe The temporal analysis of light pollution in Turkey using VIIRS data(Springer, 2021) Yerli, S. K.; Aksaker, N.; Bayazit, M.; Kurt, Z.; Aktay, A.; Erdogan, M. A.Artificial Light pollution (AL) in Turkey and in Turkish observatories between 2012-2020 have been studied using the archival data of Visible Infrared Imaging Radiometer Suite (VIIRS) instrument. The astroGIS database has been used in processing the data () Aksaker et al. (2020a). The total energy released to space from Turkey increased by 80% in 2019 with respect to 2012. In the span of the dataset, a steady and continuous increase has been observed throughout all cities of the country. On the other hand, Dark Sky Park locations, East and Southeast Anatolian regions and mostly rural areas around the cities kept their AL level constant. Four demographic parameters have been studied and they were found to be correlated very well with AL: Population (R similar or equal to 0.90; GDP (R similar or equal to 0.87); Total Power Consumption (R similar or equal to 0.66) and Outdoor Lightening (R similar or equal to 0.67). Contrary to countries acting to prevent AL increases, Turkey seems to be at the beginning of an era where AL will arithmetically increase throughout the country and enormous amount of energy will continuously escape to space and therefore will be wasted. Therefore, a preventive legislation, especially for invaluable astronomical site locations such as TURAG, TUG, DAG and cAAM where each is counted as a truly dark site due to their SQM values, has to be enacted in Turkey, in very near future.
