An optical particle counter for the regular application onboard a passenger aircraft: instrument modification, characterization and results from the first year of operation

• Main Author: Weigelt, Andreas
• Other Authors: Hermann, Markus, Wiedensohler, Alfred, Brenninkmeijer, Carl A.M., Universität Leipzig
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2015
• Subjects: info:eu-repo/classification/ddc/610; ddc:610; Aerosole; Partikelgrößenverteilung; obere Troposphäre; untere Stratosphäre; optische Partikelgrößenbestimmung; flugzeuggetragene Messungen; aerosols; particle size distribution; upper troposphere; lower stratosphere; optical particle sizing; airborne measurements; Eyjafjallajökull
• Online Access: https://nbn-resolving.org/urn:nbn:de:bsz:15-qucosa-172724; https://ul.qucosa.de/id/qucosa%3A13388; https://ul.qucosa.de/api/qucosa%3A13388/attachment/ATT-0/

To understand the contribution of aerosol particles to radiative forcing and heterogeneous chemical processes in the upper troposphere and lowermost stratosphere (UT/LMS), the knowledge of the particle size distribution is mandatory. Unfortunately, measurements in the UT/LMS are costly. Research aircrafts are expensive and thus their application is limited in time and space. Satellite remote sensing measurements provide a good temporal and spatial (horizontal) coverage, but only a limited vertical resolution and currently cannot resolve the particle size distribution. Therefore, within this thesis an optical particle counter (OPC) unit was modified for the application onboard a passenger long-haul aircraft within the CARIBIC project (www.caribic-atmospheric.com). The CARIBIC OPC unit provides regular and cost-efficient particle size distribution measurements of accumulation mode particles in the UT/LMS. In April 2010, the new OPC unit was installed for the first time onboard the Lufthansa Airbus A340 600 (D-AIHE) for the measurement of the volcanic ash cloud from the Eyjafjallajökull eruption (April to May 2010). Since June 2010 the OPC unit measures on usually four intercontinental flights per month the UT/LMS particle size distribution in the particle size range 125 to 1300 nm particle diameter. As the data acquisition stores the scattering raw signal and all housekeeping data as well, during the post flight data analysis the temporal- and size channel resolution can be flexible set. Within this work the data were analyzed with 32 size channels and 300 seconds. As aircraft-borne measurements are always time-consuming, the development of the OPC unit and the analysis routine, as well as its characterization and certification took more than two thirds of the total working time of this thesis. Therefore, the analysis of the data is limited to the first year of regular measurements until May 2011. Nevertheless, this dataset is sufficient to demonstrate the scientific relevance of these measurements. To validate ...