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1.
Analiza vpliva izgorevanja lesne biomase na koncentracije onesnaževal v zunanjem zraku : magistrsko delo
Irena Kranjc, 2024, master's thesis

Abstract: Les je v Sloveniji tradicionalno pomemben obnovljiv vir za ogrevanje v gospodinjstvih. Pri tem nastajajo delci, ki imajo negativen vpliv na zdravje. Z namenom določitve vpliva izgorevanja lesne biomase na raven onesnaženja z delci smo na več lokacijah v obdobju med 2016 in 2021 izvedli vzorčenje delcev PM10 in njihovo kemijsko analizo. Analiza je bila usmerjene v parametre povezane z izgorevanje lesne biomase: levoglukozan, manozan, galaktozan, organski in elementarni ogljik, kalij in benzo [a] piren. V obdobju med 2016 in 2021 so bile v januarju in februarju najvišje koncentracije izmerjene v letu 2017, najnižje pa v letu 2021. Razlike so povezane predvsem z različnimi meteorološkimi razmerami. Koncentracije delcev PM10, kot tudi koncentracije in deleži levoglukozana, kalija in benzo [a] pirena so bile v zimskih mesecih višje, kot v poletnem obdobju. Izjema sta le organski in elementarni ogljik, pri katerih je koncentracija v zimskem času višja, kot v poletnem, njuna deleža v delcih PM10 pa se preko leta bistveno ne spreminjata. Na podlagi razmerja med levoglukozanom in manozanom smo ugotovili, da se v Sloveniji za ogrevanje uporablja tako mehek, kot trd les. Delež delcev, ki jih lahko pripišemo izgorevanju lesne biomase je bil v januarju in februarju v obravnavnem obdobju visok – najvišji je bil v Novem mestu (52 % ± 5 %), najnižji pa v Mariboru (21 % ± 6 %).
Keywords: delci PM10, levoglukozan, manozan, izgorevanje lesne biomase, raven onesnaženja z delci, magistrske naloge
Published in RUNG: 26.09.2024; Views: 591; Downloads: 10
.pdf Full text (2,72 MB)

2.
Investigation of Aerosol Types and Vertical Distributions Using Polarization Raman Lidar over Vipava Valley
Longlong Wang, Marija Bervida, Samo Stanič, Klemen Bergant, Asta Gregorič, Luka Drinovec, Zhenping Yin, Yang Yi, Detlef Müller, Xuan Wang, 2022, original scientific article

Abstract: Aerosol direct radiative forcing is strongly dependent on aerosol distributions and aerosol types. A detailed understanding of such information is still missing at the Alpine region, which currently undergoes amplified climate warming. Our goal was to study the vertical variability of aerosol types within and above the Vipava valley (45.87◦ N, 13.90◦ E, 125 m a.s.l.) to reveal the vertical impact of each particular aerosol type on this region, a representative complex terrain in the Alpine region which often suffers from air pollution in the wintertime. This investigation was performed using the entire dataset of a dual-wavelength polarization Raman lidar system, which covers 33 nights from September to December 2017. The lidar provides measurements from midnight to early morning (typically from 00:00 to 06:00 CET) to provide aerosol-type dependent properties, which include particle linear depolarization ratio, lidar ratio at 355 nm and the aerosol backscatter Ångström exponent between 355 nm and 1064 nm. These aerosol properties were compared with similar studies, and the aerosol types were identified by the measured aerosol optical properties. Primary anthropogenic aerosols within the valley are mainly emitted from two sources: individual domestic heating systems, which mostly use biomass fuel, and traffic emissions. Natural aerosols, such as mineral dust and sea salt, are mostly transported over large distances. A mixture of two or more aerosol types was generally found. The aerosol characterization and statistical properties of vertical aerosol distributions were performed up to 3 km.
Keywords: valley air pollution, aerosol vertical distributions, lidar remote sensing, aerosol identification
Published in RUNG: 21.07.2022; Views: 2220; Downloads: 31
.pdf Full text (5,57 MB)

3.
Bora flow characteristics in a complex valley environment
Marija Bervida, Samo Stanič, Griša Močnik, Longlong Wang, Klemen Bergant, Xiaoquan Song, 2021, original scientific article

Abstract: This paper complements the existing studies of Bora flow properties in the Vipava valley with the study of Bora turbulence in a lower region of the troposphere. The turbulence characteristics of Bora flow were derived from high resolution Doppler wind lidar measurements during eight Bora wind episodes that occurred in November and December 2019. Based on the vertical profiles of wind velocity, from 80 to 180 m above the valley floor, the turbulence intensity related to all three spatial directions and the along-wind integral length scales related to three velocity components were evaluated and compared to the approximations given in international standards. The resulting turbulence characteristics of Bora flow in a deep mountain valley exhibited interesting behaviour, differing from the one expected and suggested by standards. The intensity of turbulence during Bora episodes was found to be quite strong, especially regarding the expected values for that particular category of terrain. The specific relationship between along-wind, lateral and vertical intensity was evaluated as well. The scales of turbulence in the along-wind direction were found to vary widely between different Bora episodes and were rather different from the approximations given by standards, with the most significant deviations observed for the along-wind length scale of the vertical velocity component. Finally, the periodicity of flow structures above the valley was assessed, yielding a wide range of possible periods between 1 and 10 min, thus confirming some of the previous observations from the studies of Bora in the Vipava valley.
Keywords: doppler wind lidar, Bora wind, turbulence intensity, complex terrain, turbulence integral length scale
Published in RUNG: 05.11.2021; Views: 2913; Downloads: 43
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4.
What else needs to be said on Climate Change and Droughts: Future Chalanges
Klemen Bergant, unpublished conference contribution

Abstract: Extreme weather events, including droughts, and a failure of climate-change mitigation and adaptation are the most urgent global risks taking into account their likelihood and impact. The economic loss related to extreme weather events is increasing. Observations show that droughts became more frequent and severe in the last decades across the entire Europe, and according to the climate projections the drought risk will continue to increase in 21st century, therefore we need to take action now. Efficient drought monitoring and early warning system is the basic climate change adaptation measure. Different drought monitoring and warning systems are available on local, regional and global level and for efficient management of drought risk we need to connect those tools and integrate them into multi-hazard early warning systems.
Keywords: climate change, extreme weather events, droughts, monitoring, early warnings
Published in RUNG: 07.01.2021; Views: 3237; Downloads: 0
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5.
New Data Policy in South-East Europe : (related to the SEE-MHEWS-A project)
Klemen Bergant, unpublished conference contribution

Abstract: Conference contribution presents the process of development of a new data policy for the South-East European Multi-Hazard Early Warning Advisory System project (SEE-MHEWS-A Project). The project, led by the World Meteorological Organization, is currently in a demonstration phase. National meteorological and hydrological services (NMHSs) from 17 countries in the South-East Europe are involved in the project. With common SEE-MHEWS Data Policy Agreement the involved NMHSs express their willingness and provide legal framework for the exchange of all available meteorological and hydrological data with a main purpose to improve their meteorological and hydrological forecasts and warnings. The project data policy could be seen as a first step towards the open data policy in the region.
Keywords: Multi-Hazard Early Warning System, Meteorological and Hydorlogical Warnings, Data Exchnage, Data Policy
Published in RUNG: 06.01.2021; Views: 3062; Downloads: 0
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6.
Projekcije podnebnih sprememb za Slovenijo - kako so lahko v pomoč gospodarstvu?
Klemen Bergant, 2019, published professional conference contribution

Abstract: Prispevek za posamezne letne čase povzema zaznane spremembe podnebja v Sloveniji v preteklih šestih desetletjih ter projekcije podnebnih sprememb do konca 21. stoletja. Pri projekcijah podnebnih sprememb so upoštevani različni scenariji izpustov toplogrednih plinov. Obravnavane so spremembe temperature zraka, evapotranspriacije, količine padavine in prisotnosti snežna odeja ter njihov vpliv na različne gospodarske panoge.
Keywords: podnebne spremembe, temperatura zraka, evapotranspiracija, padavine, snežna odeja, gospodarstvo
Published in RUNG: 06.01.2021; Views: 3496; Downloads: 0
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7.
Lidar Observations of Mountain Waves During Bora Episodes
Longlong Wang, Marija Bervida, Samo Stanič, Klemen Bergant, William Eichinger, Benedikt Strajnar, 2020, published scientific conference contribution

Abstract: Airflows over mountain barriers in the Alpine region may give rise to strong, gusty downslope winds, called Bora. Oscillations, caused by the flow over an orographic barrier, lead to formation of mountain waves. These waves can only rarely be observed visually and can, in general, not be reliably reproduced by numerical models. Using aerosols as tracers for airmass motion, mountain waves were experimentally observed during Bora outbreak in the Vipava valley, Slovenia, on 24-25 January 2019 by two lidar systems: a vertical scanning lidar positioned just below the peak of the lee side of the mountain range and a fixed direction lidar at valley floor, which were set up to retrieve two-dimensional structure of the airflow over the orographic barrier into the valley. Based on the lidar data, we determined the thickness of airmass layer exhibiting downslope motion, observed hydraulic jump phenomena that gave rise to mountain waves and characterized their properties.
Keywords: Bora, mountain waves, lidar observations
Published in RUNG: 08.07.2020; Views: 3668; Downloads: 0
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8.
Near-Ground Profile of Bora Wind Speed at Razdrto, Slovenia
Marija Bervida, Samo Stanič, Klemen Bergant, Benedikt Strajnar, 2019, original scientific article

Abstract: Southwest Slovenia is a region well-known for frequent episodes of strong and gusty Bora wind, which may damage structures, affect traffic, and poses threats to human safety in general. With the increased availability of computational power, the interest in high resolution modeling of Bora on local scales is growing. To model it adequately, the flow characteristics of Bora should be experimentally investigated and parameterized. This study presents the analysis of wind speed vertical profiles at Razdrto, Slovenia, a location strongly exposed to Bora during six Bora episodes of different duration, appearing between April 2010 and May 2011. The empirical power law and the logarithmic law for Bora wind, commonly used for the description of neutrally stratified atmosphere, were evaluated for 10-min averaged wind speed data measured at four different heights. Power law and logarithmic law wind speed profiles, which are commonly used in high resolution computational models, were found to approximate well the measured data. The obtained power law coefficient and logarithmic law parameters, which are for modeling purposes commonly taken to be constant for a specific site, were found to vary significantly between different Bora episodes, most notably due to different wind direction over complex terrain. To increase modeling precision, the effects of local topography on wind profile parameters needs to be experimentally assessed and implemented.
Keywords: Bora wind, logarithmic law, power law, roughness length, wind profile
Published in RUNG: 04.10.2019; Views: 4416; Downloads: 113
.pdf Full text (5,90 MB)

9.
Properties of tropospheric aerosols observed over southwest Slovenia
Tingyao He, Yingying Chen, Samo Stanič, Klemen Bergant, Fei Gao, Dengxin Hua, 2018, original scientific article

Abstract: 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.
Keywords: Aerosol, Optical depth, Lidar, Atmospheric boundary layer
Published in RUNG: 22.02.2019; Views: 4725; Downloads: 0
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10.
Bora wind, Wind speed vertical profile, Logarithmic law, Power law
Marija Bervida, Samo Stanič, Klemen Bergant, 2018, published scientific conference contribution

Abstract: 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.
Keywords: Bora wind, Wind speed vertical profile, Logarithmic law, Power law
Published in RUNG: 07.02.2019; Views: 5090; Downloads: 28
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