The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
T Bretz - One of the best experts on this subject based on the ideXlab platform.
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a method to correct iact data for Atmospheric Absorption due to the saharan air layer
HIGH ENERGY GAMMA‐RAY ASTRONOMY: Proceedings of the 4th International Meeting on#N#High Energy Gamma‐Ray Astronomy, 2009Co-Authors: D Dorner, K Nilsson, T BretzAbstract:Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.
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a method to correct iact data for Atmospheric Absorption due to the saharan air layer
Astronomy and Astrophysics, 2009Co-Authors: D Dorner, K Nilsson, T BretzAbstract:Context. Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Aims. To correlate IACT data with other measurements, e.g. long-term monitoring or Multi-Wavelength (MWL) studies, an accurate flux determination is mandatory. Therefore, a method to correct the data for the effect of the SAL is required. Methods. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. Results. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.
D Dorner - One of the best experts on this subject based on the ideXlab platform.
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a method to correct iact data for Atmospheric Absorption due to the saharan air layer
HIGH ENERGY GAMMA‐RAY ASTRONOMY: Proceedings of the 4th International Meeting on#N#High Energy Gamma‐Ray Astronomy, 2009Co-Authors: D Dorner, K Nilsson, T BretzAbstract:Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.
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a method to correct iact data for Atmospheric Absorption due to the saharan air layer
Astronomy and Astrophysics, 2009Co-Authors: D Dorner, K Nilsson, T BretzAbstract:Context. Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Aims. To correlate IACT data with other measurements, e.g. long-term monitoring or Multi-Wavelength (MWL) studies, an accurate flux determination is mandatory. Therefore, a method to correct the data for the effect of the SAL is required. Methods. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. Results. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.
Tang Lingli - One of the best experts on this subject based on the ideXlab platform.
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WHISPERS - A temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature from hyperspectral thermal infrared data
2016 8th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS), 2016Co-Authors: Chen Mengshuo, Qian Yonggang, Wang Ning, Ma Lingling, Li Chuanrong, Tang LingliAbstract:Land surface temperature and emissivity separation (TES) is a key problem in thermal infrared (TIR) remote sensing. However, because of the ill-posed problem, the retrieval accuracy still needs to be improved. Through exploring the offset characteristics of Atmospheric downward radiance, a temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature is proposed from hyperspectral thermal infrared data. Furthermore, an optimal channel selection is carried out to improve the efficiency and accuracy of method. The simulated results show that modeling errors less than 0.4K for temperature and 1.5% for relative emissivity for contrast materials and the accuracy is similar to the ISSTES method (Borel, 2008) for high emissivity materials. Furthermore, the proposed method can enhance the retrieval accuracy for low emissivity materials, that is approximately temperature 0.5 K and emissivity 2.1%.
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A temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature from hyperspectral thermal infrared data
2016 8th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS), 2016Co-Authors: Chen Mengshuo, Qian Yonggang, Wang Ning, Ma Lingling, Li Chuanrong, Tang LingliAbstract:Land surface temperature and emissivity separation (TES) is a key problem in thermal infrared (TIR) remote sensing. However, because of the ill-posed problem, the retrieval accuracy still needs to be improved. Through exploring the offset characteristics of Atmospheric downward radiance, a temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature is proposed from hyperspectral thermal infrared data. Furthermore, an optimal channel selection is carried out to improve the efficiency and accuracy of method. The simulated results show that modeling errors less than 0.4K for temperature and 1.5% for relative emissivity for contrast materials and the accuracy is similar to the ISSTES method (Borel, 2008) for high emissivity materials. Furthermore, the proposed method can enhance the retrieval accuracy for low emissivity materials, that is approximately temperature 0.5 K and emissivity 2.1%.
Liandong Wang - One of the best experts on this subject based on the ideXlab platform.
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Aircraft THz wave ground detection Atmospheric Absorption attenuation calculation
2016 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), 2016Co-Authors: Yahua Wang, Xiaofan Yang, Yonghu Zeng, Liandong WangAbstract:Terahertz (THz) wave is 0.1 to 10THz electromagnetic wave, which has the advantages of wide frequency band and low energy. In the field of space exploration, THz has important application prospects. Up to now, the Atmospheric Absorption attenuation model of THz wave is mostly horizontal transmission attenuation model. However, most aircraft ground detection is under slant path, not horizontal. Based on ITU THz wave Atmospheric Absorption attenuation model, this paper deduces the reasonable atmosphere attenuation calculation method of THz wave propagation under slant path, and completes quantitative calculation.
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China different heights annually THz wave Atmospheric Absorption calculation
2016 IEEE International Conference on Ubiquitous Wireless Broadband (ICUWB), 2016Co-Authors: Xiaofan Yang, Yahua Wang, Yonghu Zeng, Liandong WangAbstract:The quantitative calculation of THz wave Atmospheric Absorption attenuation, especially at actually region's different heights, are always been fundamental and key technology application for variety terahertz communication modes, such as wideband & high-speed network, astro-satellite communication, altitude aero-craft communication, long distance vast data transfer, short range wireless security communication etc. In this paper, the 2012 annually reanalysis data selected from National Centers for Environmental Prediction (NCEP) is employing to calculate the China region THz wave statistical monthly Atmospheric Absorption attenuation at different heights. Optimal Spline-3 function fitting method is using to fit NCEP discrete meteorological data into continuous curves. Based on Millimeter Propagation Model (MPM) as well as ITU Recommendation, the paper made China 2012 monthly barometric pressure, temperature, relative humidity curves, and different heights THz wave Oxygen and water vapor Absorption comparison to get China region's statistical THz wave Atmospheric Absorption universal principles.
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China annually statistical THz wave Atmospheric slant route propagation attenuation calculation
2016 IEEE 9th UK-Europe-China Workshop on Millimetre Waves and Terahertz Technologies (UCMMT), 2016Co-Authors: Xiaofan Yang, Yahua Wang, Yonghu Zeng, Liandong WangAbstract:The Atmospheric attenuation of THz wave propagation is closely related to the weather condition, region height and meteorological parameter. The quantitative calculation of THz wave Atmospheric Absorption attenuation under slant path, especially long term statistical at actually region, are always been fundamental and key technology for variety terahertz communication modes application. However, up to now, the established THz wave Atmospheric Absorption attenuation model is mostly under horizontal route, not slant. Besides, mostly THz wave Atmospheric Absorption attenuation calculation is under instantaneous meteorological environment, there are almost no actually region's long-time THz wave statistical Atmospheric Absorption attenuation calculation results. Based on International Telecommunication Union Radio communication Sector's THz wave Atmospheric Absorption attenuation model and 2012 annually reanalysis data selected from National Centers for Environmental Prediction (NCEP), this paper deduces the China region THz wave Atmospheric slant route Absorption attenuation analysis method, and completes its quantitative calculation.
Olivier Boucher - One of the best experts on this subject based on the ideXlab platform.
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impact of nonabsorbing anthropogenic aerosols on clear sky Atmospheric Absorption
Journal of Geophysical Research, 2006Co-Authors: P Stier, John H Seinfeld, Stefan Kinne, Johann Feichter, Olivier BoucherAbstract:[1] Absorption of solar radiation by Atmospheric aerosol has become recognized as important in regional and global climate. Nonabsorbing, hydrophilic aerosols, such as sulfate, potentially affect Atmospheric Absorption in opposing ways: first, decreasing Absorption through aging initially hydrophobic black carbon (BC) to a hydrophilic state, enhancing its removal by wet scavenging, and consequently decreasing BC lifetime and abundance, and second, increasing Absorption through enhancement of the BC Absorption efficiency by internal mixing as well as through increasing the amount of diffuse solar radiation in the atmosphere. On the basis of General Circulation Model studies with an embedded microphysical aerosol module we systematically demonstrate the significance of these mechanisms both on the global and regional scales. In remote transport regions, the first mechanism prevails, reducing Atmospheric Absorption, whereas in the vicinity of source regions, despite enhanced wet scavenging, Absorption is enhanced owing to the prevalence of the second mechanisms. Our findings imply that the sulfur to BC emission ratio plays a key role in aerosol Absorption.
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Impact of nonabsorbing anthropogenic aerosols on clear‐sky Atmospheric Absorption
Journal of Geophysical Research, 2006Co-Authors: P Stier, John H Seinfeld, Stefan Kinne, Johann Feichter, Olivier BoucherAbstract:[1] Absorption of solar radiation by Atmospheric aerosol has become recognized as important in regional and global climate. Nonabsorbing, hydrophilic aerosols, such as sulfate, potentially affect Atmospheric Absorption in opposing ways: first, decreasing Absorption through aging initially hydrophobic black carbon (BC) to a hydrophilic state, enhancing its removal by wet scavenging, and consequently decreasing BC lifetime and abundance, and second, increasing Absorption through enhancement of the BC Absorption efficiency by internal mixing as well as through increasing the amount of diffuse solar radiation in the atmosphere. On the basis of General Circulation Model studies with an embedded microphysical aerosol module we systematically demonstrate the significance of these mechanisms both on the global and regional scales. In remote transport regions, the first mechanism prevails, reducing Atmospheric Absorption, whereas in the vicinity of source regions, despite enhanced wet scavenging, Absorption is enhanced owing to the prevalence of the second mechanisms. Our findings imply that the sulfur to BC emission ratio plays a key role in aerosol Absorption.
