INSTRUMENT INTERCOMPARISON STUDY ON CLOUD DROPLET SIZE DISTRIBUTION MEASUREMENTS - HOLOGRAPHY VS LASER OPTICAL-PARTICLE COUNTER

During the EUROTRAC Ground Based Cloud Experiment (GCE) 1990, a newly developed HODAR (Holographic Droplet End Aerosol Recording) was operated for the first time to measure cloud droplet size distributions by recording Fraunhofer in-line holograms of small cloud sample volumes in situ and analyzing the holographic images in the laboratory. This technical note compares the resulting size distributions with those obtained from two FSSP-100 laser optical particle counters. For all holograms analyzed during the GCE90 field experiment, the size distributions obtained from the two different methods agree well. Additionally, the liquid water contents (LWC) were measured directly by a Gerber particulate volume monitor PVM-100. The LWC calculated from the measured droplet size distributions deviate from the PVM-100 data.