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    Lidar/radar approach to quantify the dust impact on ice nucleation in mid and high level clouds
    (Les Ulis : EDP Sciences, 2019) Ansmann, Albert; Mamouri, Rodanthi-Elisavet; Bühl, Johannes; Seifert, Patric; Engelmann, Ronny; Nisantzi, Agyro; Hofer, Julian; Baars, Holger
    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. © 2019 The Authors, published by EDP Sciences.
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    Estimation of dust related ice nucleating particles in the atmosphere: Comparison of profiling and in-situ measurements
    (Les Ulis : EDP Sciences, 2019) Haarig, Moritz; Ansmann, Albert; Walser, Adrian; Baars, Holger; Urbanneck, Claudia; Weinzierl, Bernadett; Schöberl, Manuel; Dollner, Maximilian; Mamouri, Rodanthi; Althausen, Dietrich
    Vertical profiles of number concentrations of dust particles relevant for ice nucleation in clouds are derived from lidar measurements. The results are compared to coincidental airborne in-situ measurements of particle number and surface area concentrations in the dust layer. The observations were performed in long-range transported Saharan dust at Barbados and Asian dust at Cyprus. The Asian dust data analysis is ongoing. A comparison of Asian and Saharan dust will be given at the conference. Concentrations of ice nucleating particles in the order of 10 to 1000 per cm-3 in the dust layer are derived for a temperature of-25°C at Barbados. The method can be used to continuously monitor the concentration of ice nucleating dust particles vertically resolved from lidar measurements. © 2019 The Authors, published by EDP Sciences.
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    Detrainment Dominates CCN Concentrations Around Non-Precipitating Convective Clouds Over the Amazon
    (Hoboken, NJ : Wiley, 2022) Braga, Ramon C.; Rosenfeld, Daniel; Andreae, Meinrat O.; Pöhlker, Christopher; Pöschl, Ulrich; Voigt, Christiane; Weinzierl, Bernadett; Wendisch, Manfred; Pöhlker, Mira L.; Harrison, Daniel
    We investigated the relationship between the number concentration of cloud droplets (Nd) in ice-free convective clouds and of particles large enough to act as cloud condensation nuclei (CCN) measured at the lateral boundaries of cloud elements. The data were collected during the ACRIDICON-CHUVA aircraft campaign over the Amazon Basin. The results indicate that the CCN particles at the lateral cloud boundaries are dominated by detrainment from the cloud. The CCN concentrations detrained from non-precipitating convective clouds are smaller compared to below cloud bases. The detrained CCN particles from precipitating cloud volumes have relatively larger sizes, but lower concentrations. Our findings indicate that CCN particles ingested from below cloud bases are activated into cloud droplets, which evaporate at the lateral boundaries and above cloud base and release the CCN again to ambient cloud-free air, after some cloud processing. These results support the hypothesis that the CCN around the cloud are cloud-processed.