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An Overview of the ASKOS Campaign in Cabo Verde
Eleni Marinou, Jesús Yus-Díez, Griša Močnik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: In the framework of the ESA-NASA Joint Aeolus Tropical Atlantic Campaign (JATAC), the ASKOS experiment was implemented during the summer and autumn of 2021 and 2022. ASKOS comprised roughly 9 weeks of measurements in the Saharan dust outflow towards the North Atlantic, with operations conducted from the Cabo Verde Islands. Through its unprecedented dataset of synergistic measurements in the region, ASKOS will allow for the calibration and validation of the aerosol/cloud product from Aeolus and the preparation of the terrain for EarthCARE cal/val activities. Moreover, ASKOS marks a turning point in our ability to study Saharan dust properties and the processes affecting its atmospheric transport, as well as the link to other components of the Earth’s system, such as the effect of dust particles on cloud formation over the Eastern Atlantic and the effect of large and giant particles on radiation. This is possible through the synergy of diverse observations acquired during the experiment, which include intense 24/7 ground-based aerosol, cloud, wind, and radiation remote sensing measurements, and UAV-based aerosol in situ measurements within the Saharan air layer, up to 5.3 km altitude, offering particle size-distributions up to 40 μm as well as sample collection for mineralogical analysis. We provide an outline of the novel measurements along with the main scientific objectives of ASKOS. The campaign data will be publicly available by September of 2023 through the EVDC portal (ESA Validation Data Center).
Ključne besede: experimental campaign, remote sensing, lidar, radar, radiosondes, radiation, desert dust, in-situ, aerosol, optical properties, scattering, absorption, ASKOS
Objavljeno v RUNG: 25.09.2023; Ogledov: 298; Prenosov: 4
.pdf Celotno besedilo (4,87 MB)
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Investigation of Aerosol Types and Vertical Distributions Using Polarization Raman Lidar over Vipava Valley
Longlong Wang, Marija Bervida Mačak, Samo Stanič, Klemen Bergant, Asta Gregorič, Luka Drinovec, Zhenping Yin, Yang Yi, Detlef Müller, Xuan Wang, 2022, izvirni znanstveni članek

Opis: 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.
Ključne besede: valley air pollution, aerosol vertical distributions, lidar remote sensing, aerosol identification
Objavljeno v RUNG: 21.07.2022; Ogledov: 1056; Prenosov: 25
.pdf Celotno besedilo (5,57 MB)

Gravity wave instability structures and turbulence from more than 1.5 years of OH[ast] airglow imager observations in Slovenia
René Sedlak, Patrick Hannawald, Carsten Schmidt, Sabine Wüst, Michael Bittner, Samo Stanič, 2021, izvirni znanstveni članek

Opis: We analyzed 286 nights of data from the OH* airglow imager FAIM 3 (Fast Airglow IMager) acquired at Otlica Observatory, Slovenia, between 26 October 2017 and 6 June 2019. Measurements were performed with a spatial resolution of 24 m per pixel and a temporal resolution of 2.8 s. Multiple turbulence episodes were observed and the energy dissipation rate in the upper mesosphere/lower thermosphere region was estimated from image sequences in 25 cases. Values range around 0.08 and 9.03 W/kg and would lead to an approximated localized maximum heating of 0.03–3.02 K per turbulence event.
Ključne besede: upper mesosphere, lower thermosphere, remote sensing, gravity waves, turbulence, Bora episodes
Objavljeno v RUNG: 25.10.2021; Ogledov: 1498; Prenosov: 0
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Two-wavelength polarization Raman lidar : Operating manual - v1.0
Miha Živec, Longlong Wang, elaborat, predštudija, študija

Opis: This document presents the configurations, operation, calibration procedures and maintenance instructions for the users of Raman lidar.
Ključne besede: Raman lidar, remote sensing, operating manual
Objavljeno v RUNG: 21.05.2020; Ogledov: 2805; Prenosov: 0
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Air Shower Detection by Bistatic Radar
M. Abou Bakr Othman, J. P. Lundquist, 2011, objavljeni znanstveni prispevek na konferenci

Opis: Progress in the field of high‐energy cosmic rays is currently limited by the rarity of the most interesting rays striking the Earth. Indeed, the continuation of the field beyond the current generation of observatories may become financially and practically impossible if new ways are not found to achieve remote coverage over large portions of the Earth’s surface. We describe the development of an observatory based on such a new technique: the remote sensing via bistatic radar technology of cosmic ray induced extensive air showers. We build on pilot studies performed by MARIACHI which have demonstrated that air shower radar echoes are detectable, the opportunity afforded by the location of the Northern Hemisphere’s largest “conventional” cosmic ray observatory (The Telescope Array) in radio‐quiet western Utah, and the donation of analog television transmission equipment to this effort by a local television station.
Ključne besede: UHECR, Remote sensing, Television broadcasting, Cosmic rays, General procedures and instrumentation, Radar telescopes
Objavljeno v RUNG: 29.04.2020; Ogledov: 2342; Prenosov: 0
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Comparison and complementary use of in situ and remote sensing aerosol measurements in the Athens Metropolitan Area
S. Vratolis, Griša Močnik, Konstantinos Eleftheriadis, 2020, izvirni znanstveni članek

Opis: In the summer of 2014 in situ and remote sensing instruments were deployed in Athens, in order to study the concentration, physical properties, and chemical composition of aerosols. In this manuscript we aim to combine the measurements of collocated in situ and remote sensing instruments by comparison and complementary use, in order to increase the accuracy of predictions concerning climate change and human health. We also develop a new method in order to select days when a direct comparison on in situ and remote sensing instruments is possible. On selected days that displayed significant turbulence up to approximately 1000 m above ground level (agl), we acquired the aerosol extinction or scattering coefficient by in situ instruments using three approaches. In the first approach the aerosol extinction coefficient was acquired by adding a Nephelometer scattering coefficient in ambient conditions and an Aethalometer absorption coefficient. The correlation between the in situ and remote sensing instruments was good (coefficient of determination equal to 0.69). In the second approach we acquired the aerosol refractive index by fitting dry Nephelometer and Aethalometer measurements with Mie algorithm calculations of the scattering and absorption coefficients for the size distribution up to a maximum diameter of 1000 nm obtained by in situ instruments. The correlation in this case was relatively good ( equal to 0.56). Our next step was to compare the extinction coefficient acquired by remote sensing instruments to the scattering coefficient calculated by Mie algorithm using the size distribution up to a maximum diameter of 1000 nm and the equivalent refractive index (), which is acquired by the comparison of the size distributions obtained by a Scanning Mobility Particle Sizer (SMPS) and an Optical Particle Counter (OPC). The agreement between the in situ and remote sensing instruments in this case was not satisfactory ( equal to 0.35). The last comparison for the selected days was between the aerosol extinction Ångström exponent acquired by in situ and remote sensing instruments. The correlation was not satisfactory ( equal to 0.4), probably due to differences in the number size distributions present in the air volumes measured by in situ and remote sensing instruments. We also present a day that a Saharan dust event occurred in Athens in order to demonstrate the information we obtain through the synergy of in situ and remote sensing instruments on how regional aerosol is added to local aerosol, especially during pollution events due to long range transport.
Ključne besede: Aerosol mixing in the vertical, In situ — Remote sensing comparison, Regional aerosol addition to local aerosol
Objavljeno v RUNG: 09.04.2020; Ogledov: 2599; Prenosov: 0
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Retrieval of Vertical Mass Concentration Distributions—Vipava Valley Case Study
Longlong 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: 3813; Prenosov: 111
.pdf Celotno besedilo (7,43 MB)

Longlong 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: 6847; Prenosov: 157
.pdf Celotno besedilo (29,39 MB)

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