Abstract
Abstract. The microphysical properties of cloud droplets, such as droplet size distribution and droplet number concentration, were studied. A series of field experiments was performed in the summer of 2019 at the Umweltforschungsstation Schneefernerhaus (UFS), an environmental research station located just below the peak of the Zugspitze mountain in the German Alps. A VisiSize D30 manufactured by Oxford Laser Ltd., which is a shadowgraph imaging instrument, was utilized for the first time to measure the size and velocity of cloud droplets during this campaign. Furthermore, a phase Doppler interferometer (PDI) device, manufactured by Artium Tech. Inc., was simultaneously measuring cloud droplets. After applying modifications to the built-in software algorithms, the results from the two instruments show reasonable agreement regarding droplet sizing and velocimetry for droplet diameters larger than 13 µm. Moreover, discrepancies were observed concerning the droplet number concentration results, especially with smaller droplet sizes. Further investigation by applying appropriate filters to the data allowed the attribution of the discrepancies to two phenomena: the different optical performance of the sensors with regard to small droplets and high turbulent velocity fluctuations relative to the mean flow that result in an uncertain estimate of the volume of air passing through the PDI probe volume.
Highlights
The environmental research station Schneefernerhaus (UFS) is Germany’s highest research station, constructed on the southern side of the Zugspitze mountain in the German Alps at a height of 2650 m
The presented data are either (1) “raw data” of the detected size and velocity of the droplets; (2) data resulting from the live, internal processing of the instrument software during each measurement; or (3) “modified data”, which are obtained after applying some or all of the modifications and filters described in Sect. 2.2 to the raw data
To distinguish between different data processing methods, we use the terms introduced in Sect. 2: default or corrected sample volume for the VisiSize, and original or modified droplet number concentration (DNC) methods for the phase Doppler interferometer (PDI)
Summary
The environmental research station Schneefernerhaus (UFS) is Germany’s highest research station, constructed on the southern side of the Zugspitze mountain in the German Alps at a height of 2650 m. There have been several recent atmospheric studies, including in situ measurements and remote sensing of aerosols as well as greenhouse gases, conducted at the UFS (e.g., Klanner et al, 2018; Ghasemifard et al, 2019; Wang et al, 2020). It has been used as the measurement site in several campaigns on cloud research (e.g., Siebert and Teichmann, 2000; Wirth et al, 2012; Risius et al, 2015). Later, using meteorological data collected by the German Weather Service (Deutscher Wetterdienst, DWD) from 2000 to 2012 and turbulence measurements recorded by multiple ultrasonic sensors in 2010, the UFS was introduced as a wellsuited station for cloud–turbulence research, especially for measurements that would be difficult to obtain from an airborne system (Risius et al, 2015; Siebert et al, 2015)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
