211. Ultra-high energy neutrinos searches with the Pierre Auger ObservatoryMarta Trini, Danilo Zavrtanik, Danilo Zavrtanik, Serguei Vorobiov, Samo Stanič, Gašper Kukec-Mezek, Lukas Zehrer, 2019, objavljeni znanstveni prispevek na konferenci Opis: In the EeV range, neutrinos are expected to be produced by ultra-high energy cosmic rays interactions with the Cosmic Microwave Background during propagation in the Universe. We report on the search for ultra-high energy neutrinos in data collected with the Surface Detector of the Pierre Auger Observatory. The searches are most efficient in the zenith angle range from 60 degrees to 95 degrees with tau neutrinos skimming in the Earth playing dominant role. The present non-detection of UHE neutrinos in the Pierre Auger Observatory excludes the most optimistic scenarios of neutrino production in terms of UHE cosmic rays chemical composition and cosmological evolution of the acceleration sites. We also report on the searches for neutrinos in coincidence with the recent Gravitational Wave events detected by LIGO/Virgo.
Ključne besede: EeV neutrinos, Pierre Auger Observatory, limits
Objavljeno v RUNG: 26.02.2019; Ogledov: 3762; Prenosov: 0
Gradivo ima več datotek! Več... |
212. Properties of tropospheric aerosols observed over southwest SloveniaTingyao He, Yingying Chen, Samo Stanič, Klemen Bergant, Fei Gao, Dengxin Hua, 2018, izvirni znanstveni članek Opis: From August to October 2010 lidar measurements of aerosols in the troposphere were performed at Otlica observatory, Slovenia, using a vertical scanning elastic lidar. The lidar data sample, which contains 38 nighttime vertical profiles of the mean aerosol extinction, was combined with continuous ozone concen- tration (O3), particulate matter concentrations (PM) and daily radiosonde data. The obtained radiosonde- and lidar-derived heights of the atmospheric boundary layer (ABL), which varied considerably from day to day, were found to be in good agreement. The mean values of the aerosol optical depth (AOD) at 355 nm, were calculated separately for the ABL and for the free troposphere (FT). A ten-fold increase of the FT AOD was observed during the days with predicted presence of Saharan dust above the lidar site. To correlate AOD values with the type and origin of aerosols, backward trajectories of air-masses above Otlica were modeled using the HYSPLIT model and clustered. High ABL AOD values were found to be correlated with local circulations and slowly approaching air masses from the Balkans and low values with northwestern flows. The highest values correlated with southwestern flows originating in northern Africa.
Ključne besede: Aerosol, Optical depth, Lidar, Atmospheric boundary layer
Objavljeno v RUNG: 22.02.2019; Ogledov: 3820; Prenosov: 0
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213. Bora wind, Wind speed vertical profile, Logarithmic law, Power lawMarija Bervida, Samo Stanič, Klemen Bergant, 2018, objavljeni znanstveni prispevek na konferenci Opis: Bora is cold and gusty downslope wind with variable gust frequency and duration, appearing on the lee side of Dinaric Alps. Its flow characteristics are unique and theoretically still not fully described, especially for modeling purposes. We present an analysis of the wind speed vertical profiles at Razdrto, which lies in a gap between the Nanos and Javorniki plateau in southwest Slovenia and is strongly exposed to Bora. An analysis of the vertical wind speed profiles during Bora episodes is based on experimental wind data, provided by Helikopter energija, for six Bora events of different duration, appearing between April 2010 and May 2011. Average wind speed in 10-minute intervals was collected at four different heights (20, 31, 40 and 41.7 m above the ground)at the wind turbine site in Razdrto using cup anemometers. Wind direction data with same temporal resolution was obtained from a single wind vane placed at 40.9 m above the ground. Based on the collected data, the applicability of the empirical power-law and the logarithmic law profiles, commonly used for the description of neutrally stratified atmosphere, was investigated for the case of Bora. The parameters for the power-law and logarithmic law were obtained by fitting the wind speed data using linear regression method and are compared to standard values for that particular type of terrain. The quality of fits was very good with r2 above 0.9, indicating that both power-law and logarithmic law adequately describe mean horizontal Bora wind. The median value of the power-law coefficient was found to be 0.16±0.03, which is consistent with standard value for neutral atmosphere (0.143). The aerodynamic roughness varied from 0.003 m to 0.22 m with the median value of 0.09±0.07, which describes open level country terrain with some trees. The event in November 2010 with large roughness is expected to be due to specific wind direction and surface conditions.
Ključne besede: Bora wind, Wind speed vertical profile, Logarithmic law, Power law
Objavljeno v RUNG: 07.02.2019; Ogledov: 4002; Prenosov: 27
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214. Retrieval of Vertical Mass Concentration Distributions—Vipava Valley Case StudyLonglong Wang, Samo Stanič, Klemen Bergant, William Eichinger, Griša Močnik, Luka Drinovec, Janja Vaupotič, Miloš Miler, Mateja Gosar, Asta Gregorič, 2019, izvirni znanstveni članek Opis: Aerosol vertical profiles are valuable inputs for the evaluation of aerosol transport models, in order to improve the understanding of aerosol pollution ventilation processes which drive the dispersion of pollutants in mountainous regions. With the aim of providing high-accuracy vertical distributions of particle mass concentration for the study of aerosol dispersion in small-scale valleys, vertical profiles of aerosol mass concentration for aerosols from different sources (including Saharan dust and local biomass burning events) were investigated over the Vipava valley, Slovenia, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. The analysis was based on datasets taken between 1–30 April 2016. In-situ measurements of aerosol size, absorption, and mass concentration were combined with lidar remote sensing, where vertical profiles of aerosol concentration were retrieved. Aerosol samples were characterized by SEM-EDX, to obtain aerosol morphology and chemical composition. Two cases with expected dominant presence of different specific aerosol types (mineral dust and biomass-burning aerosols) show significantly different aerosol properties and distributions within the valley. In the mineral dust case, we observed a decrease of the elevated aerosol layer height and subsequent spreading of mineral dust within the valley, while in the biomass-burning case we observed the lifting of aerosols above the planetary boundary layer (PBL). All uncertainties of size and assumed optical properties, combined, amount to the total uncertainty of aerosol mass concentrations below 30% within the valley. We have also identified the most indicative in-situ parameters for identification of aerosol type.
Ključne besede: valley air pollution, aerosol vertical distributions, lidar remote sensing, in-situ measurements, aerosol identification
Objavljeno v RUNG: 09.01.2019; Ogledov: 4197; Prenosov: 113
 Celotno besedilo (7,43 MB) |
215. Aerosol monitoring over Vipava valley using Raman polarization lidarLonglong Wang, Samo Stanič, Klemen Bergant, William Eichinger, Asta Gregorič, Griša Močnik, Luka Drinovec, 2018, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Vipava valley in southwest Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin in mountainous terrain. An investigation of aerosol properties throughout the troposphere in different atmospheric conditions was made possible by a deployment of a two-wavelength polarization Raman lidar system combining with in-situ measurements in the valley (in the town of Ajdovščina) from September 2017. Using its aerosol identification capabilities, which are based on particle depolarization ratio and lidar ratio measurements, it was possible to identify predominant aerosol types in the observed atmospheric structures, for example in different atmospheric layers in the case of stratified atmosphere. Primary anthropogenic aerosols within the valley were found to be mainly emitted from two sources: individual domestic heating systems, which mostly use biomass fuel, and from traffic. A considerable fraction of natural aerosols (for example mineral dust and sea salt), transported over large distances, were observed both above and entering into the planetary boundary layer. According to the properties of different aerosol types, backscatter contribution of each aerosol type was evaluated and the corresponding extinction contribution was derived from lidar observations. Statistical analysis of the presence of different aerosol types was performed on the entire available dataset from 2017 and 2018.
Ključne besede: lidar, aerosol type, Vipava valley
Objavljeno v RUNG: 03.12.2018; Ogledov: 4285; Prenosov: 0
Gradivo ima več datotek! Več... |
216. STUDY OF ATMOSPHERIC AEROSOL PROPERTIES IN THE VIPAVA VALLEYLonglong Wang, doktorska disertacija Opis: The aim of the dissertation was to study aerosol loading distributions and properties over the Vipava valley, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin.
An infrared Mie and a two-wavelength polarization Raman lidar systems
were used as main detection tools. The polarization Raman lidar, which
provides the capability to extract the extinction coefficient, backscatter coefficients, depolarization ratio, backscatter Ångström exponent, lidar ratio and
water vapor mixing ratio profiles, was itself designed, built and calibrated as
a part of this thesis. Lidar data, combined with in-situ measurements, was
used to determine detailed information on different aerosol types. Vertical
profiles of aerosol mass concentration were extracted from the Mie lidar data
taken in April 2016, where the in-situ measurements of aerosol size distribution and number concentration as well as aerosol absorption coefficient and black carbon mass concentration were used to estimate the mass extinction efficiency (MEE). Aerosol morphology and chemical composition determined by SEM-EDX on sampled particles were used for the identification
of primary aerosol types. Two cases with different atmospheric conditions
(long range mineral dust transport and local biomass burning) and different
expected the dominant presence of specific aerosol types (mineral dust and
soot) were investigated in more detail. They revealed significantly different
aerosol properties and distributions within the valley, affecting radiative heat
exchange.
A more detailed investigation of aerosol properties throughout the troposphere in different atmospheric conditions was made possible by the two-wavelength polarization Raman lidar system, deployed in Ajdovščina (town
of Vipava valley) from September 2017. Using its aerosol identification capabilities, based on particle depolarization ratio and lidar ratio measurements,
it was possible to identify predominant aerosol types in the observed atmospheric structures, for example in different atmospheric layers in the case of
the stratified atmosphere. Primary anthropogenic aerosols within the valley were found to be mainly emitted from two sources: individual domestic
heating systems, which mostly use biomass fuel and traffic. Natural aerosols,
transported over large distances, such as mineral dust and sea salt, were observed both above and entering into the planetary boundary layer. Backscatter contribution of each aerosol type was separated and the corresponding
extinction contribution was derived from lidar observations.
Ključne besede: Vipava valley, aerosol distribution, aerosol characterization, lidar
remote sensing, in-situ measurements, aerosol loading.
Objavljeno v RUNG: 23.10.2018; Ogledov: 7345; Prenosov: 157
Celotno besedilo (29,39 MB) |
217. Ognjemetom se ni treba odpovedatiSamo Stanič, 2018, intervju Opis: Pozimi je zaradi kurilne sezone in vremenskih razmer v zraku več škodljivih trdnih delcev kot ponavadi. V zadnjem času se precej govori o tem, da se razmere ob koncu leta še poslabšajo zaradi številnih ognjemetov. O onesnaženju in ognjemetih smo povprašali prof. dr. Sama Staniča, vodjo Centra za raziskave atmosfere na Univerzi v Novi Gorici.
Ključne besede: aerosoli, ognjemeti, onesnaževanje ozračja
Objavljeno v RUNG: 07.03.2018; Ogledov: 3410; Prenosov: 0
Gradivo ima več datotek! Več... |
218. Zakaj je burja najmočnejša v Vipavski dolini?Samo Stanič, 2017, intervju Opis: Ste se kdaj spraševali, zakaj je burja pri nas najmočnejša prav v Vipavski dolini? "Kriva" je pravzaprav reliefna slika Vipavske doline: burja je namreč pojav, ki nastane na zavetrni strani gorskih verig, kjer zaradi toka hladnega zraka čez oviro nastanejo močni pobočni vetrovi. Pojav je povezan s prisotnostjo toplih zračnih mas v nižinah JZ Slovenije in stabilnih hladnih zračnih mas nad osrednjo Slovenijo, ki se ob gorski pregradi prelivajo v dolino. Razgiban relief JZ Slovenije, ki se v manj kot tridesetih kilometrih preko Kraške planote in Vipavske doline dvigne na planoto Trnovskega gozda tudi s 1500 m nadmorske višine namreč omogoča razvoj burje v Vipavski dolini, katere poglavitna značilnost so močni sunki.
Ključne besede: burja, daljinsko zaznavanje, lidar, Vipavska dolina
Objavljeno v RUNG: 05.03.2018; Ogledov: 4885; Prenosov: 0
Gradivo ima več datotek! Več... |
219. All-sky search for correlations in the arrival directions of astrophysical neutrino candidates and ultrahigh-energy cosmic raysI. Al Samarai, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, objavljeni znanstveni prispevek na konferenci Ključne besede: correlations, astrophysical neutrino, ultrahigh-energy cosmic rays
Objavljeno v RUNG: 19.02.2018; Ogledov: 3464; Prenosov: 166
Celotno besedilo (3,07 MB) |
220. Testing the agreement between the Xmax distributions measured by the Pierre Auger and Telescope Array ObservatoriesV. De Souza, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, objavljeni znanstveni prispevek na konferenci Ključne besede: Xmax distributions, Pierre Auger Observatory, Telescope Array
Objavljeno v RUNG: 19.02.2018; Ogledov: 3746; Prenosov: 179
Celotno besedilo (266,09 KB) |
