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Author: Althausen, Dietrich × End date: 2019 × Start date: 2019 × Type: conferenceObject × Publisher: Les Ulis : EDP Sciences ×

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Now showing 1 - 5 of 5
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    Aerosol properties over Southeastern China from multi-wavelength Raman and depolarization lidar measurements
    (Les Ulis : EDP Sciences, 2016) Heese, Birgit; Althausen, Dietrich; Baars, Holger; Bohlmann, Stephanie; Deng, Ruru
    A dataset of particle optical properties of highly polluted urban aerosol over the Pearl River Delta, Guangzhou, China is presented. The data were derived from multi-wavelengths Raman and depolarization lidar PollyXT and AERONET sun photometer measurements. The measurement campaign was conducted from Nov 2011 to June 2012. High aerosol optical depth was observed in the polluted atmosphere over this megacity, with a mean value of 0.54 ± 0.33 and a peak value of even 1.9. For the particle characterization the lidar ratio and the linear particle depolarization ratio, both at 532 nm, were used. The mean values of these properties are 48.0 sr ± 10.7 sr for the lidar ratio and 4%+-4% for the particle depolarization ratio, which means most depolarization measurements stayed below 10%. So far, most of these results indicate urban pollution particles mixed with particles arisen from biomass and industrial burning.
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    Observation of Arabian and Saharan dust in Cyprus with a new generation of the smart Raman lidar Polly
    (Les Ulis : EDP Sciences, 2016) Engelmann, Ronny; Ansmann, Albert; Bühl, Johannes; Heese, Birgit; Baars, Holger; Althausen, Dietrich; Marinou, Eleni; Amiridis, Vassilis; Mamouri, Rodanthi-Elisavet; Vrekoussis, Mihalis
    The atmospheric science community demands for autonomous and quality-assured vertically resolved measurements of aerosol and cloud properties. Aiming this goal, TROPOS developed the fully automated multiwavelength polarization Raman lidar Polly since over 10 years [1, 2]. In cooperation with different partner research institutes the system was improved continuously. Our latest lidar developments include aside the “3+2” measurements also a near-range receiver to measure aerosol extinction and backscatter down to 120 m above the lidar, a water-vapor channel, and measurements of the linear depolarization at two wavelengths. The latest system was built in cooperation with the National Observatory of Athens (NOA). Its first campaign however was performed at the Cyprus Institute of Nicosia from March to April 2015, aiming specifically at the observation of ice nuclei with in-situ and lidar remote sensing techniques in the framework of BACCHUS [3, 4].
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    Measurement of the linear depolarization ratio of aged dust at three wavelengths (355, 532 and 1064 nm) simultaneously over Barbados
    (Les Ulis : EDP Sciences, 2016) Haarig, Moritz; Althausen, Dietrich; Ansmann, Albert; Klepel, André; Baars, Holger; Engelmann, Ronny; Groß, Silke; Freudenthaler, Volker
    A ground-based polarization Raman lidar is presented, that is able to measure the depolarization ratio at three wavelengths (355, 532 and 1064 nm) simultaneously. This new feature is implemented for the first time in a Raman lidar. It provides a full dataset of 3 backscatter coefficients, two extinction coefficients and 3 depolarization ratios (3+2+3 lidar system). To ensure the data quality, it has been compared to the well characterized two-wavelength polarization lidar POLIS. Measurements of long-range transported dust have been performed in the framework of the Saharan Aerosol Long-Range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) in the Caribbean.
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    Standards – An important step for the (public) use of lidars
    (Les Ulis : EDP Sciences, 2016) Althausen, Dietrich; Emeis, Stefan; Flentje, Harald; Guttenberger, Josef; Jäckel, Simon; Lehmann, Volker; Mattis, Ina; Münkel, Christoph; Peters, Gerhard; Ritter, Christoph; Wiegner, Matthias; Wille, Holger
    Lidar standards are needed to ensure quality and lidar product control at the interface between lidar manufacturers and lidar users. Meanwhile three lidar standards have been published by German and international standardization organizations. This paper describes the cooperation between the lidar technique inventors, lidar instrument constructors, and lidar product users to establish useful standards. Presently a backscatter lidar standard is elaborated in Germany. Key points of this standard are presented here. Two German standards were already accepted as international standards by the International Organization for Standardization (ISO). Hence, German and international organizations for the establishment of lidar standards are introduced to encourage a cooperative work on lidar standards by lidar scientists.
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    Central Asian Dust Experiment (CADEX): Multiwavelength polarization Raman lidar observations in Tajikistan
    (Les Ulis : EDP Sciences, 2016) Hofer, Julian; Althausen, Dietrich; Abdullaev, Sabur F.; Engelmann, Ronny; Baars, Holger
    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.