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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: 3052; Downloads: 31
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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: 3903; Downloads: 0
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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: 4588; Downloads: 0
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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: 5295; Downloads: 115
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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: 5918; Downloads: 29
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