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Multi-wavelength lidar measurements of the particle linear depolarization ratio of mineral dust layers at various locations around the Earth are presented from a comprehensive literature review. The values at a wavelength of 532 nm as well as the spectral slope of the depolarization ratio exhibits no significant difference between the Sahara, Arabia and Central Asia. The main difference was observed between freshly emitted and transported dust. Fresh dust has a higher depolarization ratio probably due to a higher amount of large dust particles. The depolarization ratio tends to decrease during transport time. This effect is strongest at 1064 nm and almost not present at 355 nm.

A mineralogical database is included in the simulation of mineral dust atmospheric life cycle for the chemistry and transport model COSMO5.05-MUSCAT. Evaluation of the ability of the model to reproduce the atmospheric drivers and the spatial-temporal resolution of mineral dust in the atmosphere is done through comparisons with remote sensing measurements in the Sahara Desert region for January-February 2022. Results show simultaneously good agreements and suggest that discrepancies could be explained due to the methods used for calculating mineral dust in the atmosphere not considering compositional differences.

First ever lidar observation in Tajikistan were conducted during the Central Asian Dust Experiment 2015–2016 (CADEX) in Dushanbe. Analysis of layer-mean optical properties revealed frequently low lidar ratios at enhanced depolarization ratios. These cases were categorized as background aerosol since they occurred at low extinction conditions. Such optical properties are similar to dried and therefore cubic-like shaped sea salt particles. This led to the hypothesis that Central Asian background aerosol and its optical properties are influenced by dry lakes and saline playas which are frequent in Central Asia. The goal of this study is to extend the existing data analysis with a backward trajectory-based time– height resolved air mass source attribution tool which was not yet available at the time of the CADEX campaign and its data analysis. Despite on average similar air mass origins for all cases irrespective of their optical properties, results suggest slightly more southern and south-western influenced air masses for cases with larger lidar ratios than for cases with lower lidar ratios.

In the Central Asian region, susceptibility to dust storms and escalating anthropogenic emissions poses challenges for air quality as well as environmental health. This study explores the temporal and seasonal dynamics of oxygenated polycyclic aromatic hydrocarbons (OPAHs) and aliphatic ketones in particulate matter during the Central Asian Dust Experiment (CADEX) in Dushanbe, both determined by Curie-Point Pyrolysis / Gas Chromatography Mass Spectrometry (CPP-GC/MS). The results revealed pronounced variations in the concentrations of OPAHs, particularly 9,10-anthracendione, as the most dominant compound, with a marked dominance in winter. The aliphatic ketones also displayed robust temporal variations, closely associated with combustion sources with 2-nonadecanone and 2-heptadecanone emerging as the dominant compounds. Both compound groups showed higher concentrations in winter. The impact of dust events on OPAHs was more noticeable during summer, with limited influence observed in winter. Combustion sources, particularly wood and coal burning, played a predominant role in shaping the observed concentrations, explaining most of the winter dominance. The elevated levels of OPAHs and ketones in Dushanbe underscore the need for implementing local mitigation strategies to curb exposure and potential health risks. This comprehensive analysis enhances our understanding of the intricate interplay between mineral dust, combustion sources, and atmospheric chemical composition, contributing to the development of air quality management strategies, in regions prone to dust events.

Focusing on Tajikistan, a region facing critical environmental challenges, this extended abstract provides insights into the relationship between aerosols and clouds in Central Asia by means of lidar observations. Since 2019, a novel Dual-Field-of-View (DFOV) Raman polarization lidar system in Dushanbe has provided highly-resolved data on aerosol and cloud microphysical properties. Given the limited observational experiments in Central Asia, these measurements might play a crucial role in addressing climaterelated concerns. In fact, this technological deployment might not only provide a better picture regarding the spatio-temporal distribution of mineral dust and urban emissions, but also improve our understanding regarding the complex interactions between aerosol and clouds. One of the most uncertain aspects when predicting future temperature and precipitation patterns. Furthermore, an extended trajectory-based source attribution tool has been implemented to track air masses in Tajikistan, providing enhanced support for this and future studies. This research focuses on data evaluation and analysis, building upon established lidar methodologies. The resulting insights can potentially contribute to a better understanding of the relationship between aerosols and clouds in the dry continental conditions that persists in this region.

Tajikistan is often affected by atmospheric mineral dust originating from various surrounding deserts. The direct and indirect radiative effects of that dust play a sensitive role in the Central Asian climate system and therefore need to be quantified. The Central Asian Dust Experiment (CADEX) provides for the first time an aerosol climatology for Central Asia based long-term aerosol profiling by ground-based lidar (PollyXT type) in Dushanbe, Tajikistan. For pure dust cases, mean depolarization(lidar) ratios of 0.23±0.03(44±3 sr) at 355 nm and 0.32±0.02(38±3 sr) at 532 nm wavelength have been measured. The mean extinction-related Ångström exponent was 0.18±0.15.

During the 18-month Central Asian Dust Experiment we conducted continuous lidar measurements at the Physical Technical Institute of the Academy of Sciences of Tajikistan in Dushanbe between 2015 and 2016. Mineral dust plumes from various source regions have been observed and characterized in terms of their occurrence, and their optical and microphysical properties with the Raman lidar PollyXT. Currently a new container-based lidar system is constructed which will be installed for continuous long-term measurements in Dushanbe.

Monthly mean vertical profiles of aerosol type occurrences are determined from multiwavelength Raman and polarization lidar measurements above Haifa, Israel, in 2017. This contribution presents the applied methods and threshold values. The results are discussed for one example, May 2017. This month shows more often large, non-spherical particles in lofted layers than within the planetary boundary layer. Small particles are observed at higher altitudes only when they are observed in lower altitudes, too.

Mineral dust influences climate and weather by direct and indirect effects. Surrounded by dust sources, Central Asian countries are affected by atmospheric mineral dust on a regular basis. Climate change effects like glacier retreat and desertification are prevalent in Central Asia as well. Therefore, the role of dust in the climate system in Central Asia needs to be clarified and quantified. During the Central Asian Dust EXperiment (CADEX) first lidar observations in Tajikistan were conducted. Long-term vertically resolved aerosol measurements were performed with the multiwavelength polarization Raman lidar PollyXT from March 2015 to August 2016 in Dushanbe, Tajikistan. In this contribution, a climatology of the aerosol layer heights is presented, which was retrieved from the 18-month lidar measurements. Automatic detection based on backscatter coefficient thresholds were used to retrieve the aerosol layer heights and yield similar layer heights as manual layer height determination. The significant aerosol layer height has a maximum in summer and a minimum in winter. The highest layers occurred in spring, but in summer uppermost layer heights above 6 km AGL are frequent, too.

Aerosol chemical composition was characterized during the Central Asian Dust Experiment (CADEX) at Dushanbe (Tajikistan). Aerosol samples were collected during a period of 2 months from March to May 2015 using a high volume DIGITEL DHA-80 sampler on quartz fiber filters. The filters were analyzed for their ionic, trace metals as well as organic and elemental carbon (OC/EC) content. The aerosol mass showed strong variation with mass concentration ranging from 18 μg/m3 to 110 μg/m3. The mineral dust concentrations varied between 0.9 μg/m3 and 88 μg/m3. Days of high aerosol mass loadings were dominated by mineral dust, which made up to about 80% of the aerosol mass while organic matter and inorganic ions made up about 70% of the aerosol mass during days of low aerosol mass loadings. The mineral dust composition showed different trace metal signatures in comparison to Saharan dust with higher Ca content and Ca/Fe ratios twice as high as that observed in Saharan dust. Strong influence of anthropogenic activities was observed in the trace metal concentrations with Zn and Pb concentrations ranging from 7 to 197 ng/m3 and 2 to 20 ng/m3, respectively. Mineral dust and anthropogenic activities relating to traffic, combustion as well as metallurgical industrial emissions are identified as the sources of the aerosol during this period.

We present the first attempt of a closure experiment regarding the relationship between ice nucleating particle concentration (INPC) and ice crystal number concentration (ICNC), solely based on active remote sensing. The approach combines aerosol and cloud observations with polarization lidar, Doppler lidar, and cloud radar. Several field campaigns were conducted on the island of Cyprus in the Eastern Mediterranean from 2015-2018 to study heterogeneous ice formation in altocumulus and cirrus layers embedded in Saharan dust. A case study observed on 10 April 2017 is discussed in this contribution.

Optical properties of fresh biomass burning aerosol were measured by lidar during the wild fires in Israel in November 2016. A single-wavelength lidar Polly was operated at the Technion Campus at Haifa. The detector with originally two channels at 532 and 607 nm was recently upgraded with a cross- and a co-polarised channel at 532 nm, and a rotational Raman channel at 530.2 nm. Preliminary results show high particle depolarisation ratios probably caused by soil dust and large fly-ash particles.

Mineral dust needs to be characterized comprehensively since it contributes to the climate change in Tajikistan / Central Asia. Lidar results from the measurements of mineral dust during CADEX are compared with results of sun photometer measurements, satellite-based measurements, and chemical analysis of ground samples. Although the dust is often advected from far-range sources, it impacts on the local conditions considerably.

PollyNET is a network of portable, automated, and continuously measuring Ramanpolarization lidars of type Polly operated by several institutes worldwide. The data from permanent and temporary measurements sites are automatically processed in terms of optical aerosol profiles and displayed in near-real time at polly.tropos.de. According to current schedules, the network will grow by 3-4 systems during the upcoming 2-3 years and will then comprise 11 permanent stations and 2 mobile platforms.

The Cloud-Aerosol Transport System (CATS) onboard the International Space Station (ISS), is a lidar system providing vertically resolved aerosol and cloud profiles since February 2015. In this study, the CATS aerosol product is validated against the aerosol profiles provided by the European Aerosol Research Lidar Network (EARLINET). This validation activity is based on collocated CATS-EARLINET measurements and the comparison of the particle backscatter coefficient at 1064nm.

Tajikistan is often affected by atmospheric mineral dust. The direct and indirect radiative effects of dust play a sensitive role in the climate system in Central Asia. The Central Asian Dust Experiment (CADEX) provides first lidar measurements in Tajikistan. The autonomous multiwavelength polarization Raman lidar PollyXT was operated for 1.5 years (2015/16) in Dushanbe. In spring, lofted layers of long-range transported dust and in summer/ autumn, lower laying dust from local or regional sources with large optical thicknesses occurred.

For the first time lidar measurements of vertical aerosol profiles are conducted in Tajikistan/Central Asia. These measurements just started on March 17th, 2015. They are performed within the Central Asian Dust Experiment (CADEX) in Dushanbe and they will last at least one year. The deployed system for these observations is an updated version of the multiwavelength polarization Raman lidar PollyXT. Vertical profiles of the backscatter coefficient, the extinction coefficient, and the particle depolarization ratio are measured by this instrument. A first and preliminary measurement example of an aerosol layer over Dushanbe is shown.