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Najdeno v: ključnih besedah
Ključne besede: Cherenkov Telescope Array, atmospheric monitoring, ARCADE Raman Lidar
Objavljeno: 16.02.2017; Ogledov: 2440; Prenosov: 151
Polno besedilo (1,24 MB)

Opis: Vipava valley in Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. Aerosol loading distributions and optical properties were investigated using a two-wavelength polarization Raman LiDAR, which provided extinction coefficient, backscatter coefficient, depolarization ratio, backscatter Ångström exponent and LiDAR ratio profiles. Two different representative meteorological situations were investigated to explore the possibility of identifying aerosol types present in the valley. In the first case, we investigated the effect of strong downslope (Bora) wind on aerosol structures and characteristics. In addition to observing Kelvin–Helmholtz instability above the valley, at the height of the adjacent mountain ridge, we found new evidence for Bora-induced processes which inject soil dust aerosols into the free troposphere up to twice the height of the planetary boundary layer (PBL). In the second case, we investigated aerosol properties and distributions in stable weather conditions. From the observed stratified vertical aerosol structure and specific optical properties of different layers we identified predominant aerosol types in these layers.
Najdeno v: ključnih besedah
Ključne besede: aerosol structures, aerosol characterization, polarization Raman LiDAR, Vipava valley
Objavljeno: 08.03.2019; Ogledov: 2504; Prenosov: 87
Polno besedilo (3,11 MB)

Opis: The Cherenkov Telescope Array (CTA) is the next generation ground-based observatory for gamma-ray astronomy at very-high energies. Employing more than 100 (north and south sites) Imaging Atmospheric Cherenkov Telescopes in the northern and southern hemispheres, it was designed to reach unprecedented sensitivity and energy resolution. Understanding and correcting for systematic biases on the absolute energy scale and instrument response functions will be a cru- cial issue for the performance of CTA. The Montpellier group and the Spanish/Italian/Slovenian collaboration are currently building two Raman LIDAR prototypes for the online atmospheric cal- ibration along the line-of-sight of the CTA. Requirements for such a solution include the ability to characterize aerosol extinction at two wavelengths to distances up to 30 km with an accuracy better than 5%, within exposure time scales of about a minute, steering capabilities and close interaction with the CTA array control and data acquisition system as well as other auxiliary in- struments. Our Raman LIDARs have design features that make them different from those used in atmospheric science and are characterized by large collecting mirrors (∼2.5 m 2 ), liquid light- guides that collect the light at the focal plane and transport it to the readout system, reduced acquisition time and highly precise Raman spectrometers. The Raman LIDARs will participate in a cross-calibration and characterization campaign of the atmosphere at the CTA North site at La Palma, together with other site characterization instruments. After a one-year test period there, an in-depth evaluation of the solutions adopted by the two projects will lead to a final Raman LIDAR design proposal for both CTA sites.
Najdeno v: ključnih besedah
Povzetek najdenega: ...the Spanish/Italian/Slovenian collaboration are currently building two Raman LIDAR prototypes for the online atmospheric cal- ibration along...
Ključne besede: Raman lidar atmospheric calibration Cherenkov Telescope Array
Objavljeno: 29.08.2019; Ogledov: 2082; Prenosov: 68
Polno besedilo (1,29 MB)