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A disdrometer measures the drop size distribution and velocity of falling hydrometeors.

The 2-dimensional video-disdrometer (VDIS) comprises video cameras capable of observing individual hydrometeors from views perpendicular to each other. Two CCD line scan cameras are directed towards the measurement area. Objects passing through the measurement area—which is determined by the cross-section of the two optical paths as seen from above—obstruct the light and are detected as shadows by the cameras.

Each camera contains a small embedded computer responsible for handling the data-capture process, analysis of the data, and their conversion and compression into a format suitable for further processing. Subsequently the data are transferred to the computer used for instrument control and final analysis.

In order to identify individual precipitation particles by matching their views as seen by each of the cameras, it is necessary to synchronize the shutter and control both cameras with a synchronous line trigger signal.

To reconstruct observables like falling velocity, oblateness, etc. from the datastreams of the two cameras, the two optical paths are displaced vertically by about 6mm, typically. Measuring this distance and adjusting the background illumination are the two major calibration and maintenance tasks necessary for successful operation of the device.



  • Fixed
  • AMF1
  • AMF2
  • AMF3


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Ryu J, H Song, B Sohn, and C Liu. 2021. "Global Distribution of Three Types of Drop Size Distribution Representing Heavy Rainfall from GPM/DPR Measurements." Geophysical Research Letters, 48(3), e2020GL090871, 10.1029/2020GL090871.

Jackson R, S Collis, V Louf, A Protat, D Wang, S Giangrande, E Thompson, B Dolan, and S Powell. 2021. "The development of rainfall retrievals from radar at Darwin." Atmospheric Measurement Techniques, 14(1), 10.5194/amt-14-53-2021.
Research Highlight


Ghate V, M Cadeddu, and R Wood. 2020. "Drizzle, Turbulence, and Density Currents Below Post Cold Frontal Open Cellular Marine Stratocumulus Clouds." Journal of Geophysical Research: Atmospheres, 125(19), e2019JD031586, 10.1029/2019JD031586.
Research Highlight

Li H, J Tiira, A von Lerber, and D Moisseev. 2020. "Towards the connection between snow microphysics and melting layer: insights from multifrequency and dual-polarization radar observations during BAECC." Atmospheric Chemistry and Physics, 20(15), 10.5194/acp-20-9547-2020.

Bartholomew MJ. 2020. Two-Dimensional Video Disdrometer (VDIS) Instrument Handbook. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-TR-111.

Chase R, S Nesbitt, and G McFarquhar. 2020. "Evaluation of the Microphysical Assumptions within GPM-DPR Using Ground-Based Observations of Rain and Snow." Atmosphere, 11(6), 10.3390/atmos11060619.

Hardin J, S Giangrande, and A Zhou. 2020. Laser Disdrometer Quantities (LDQUANTS) and Video Disdrometer Quantities (VDISQUANTS) Value-Added Products Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-TR-221.

Conrick R, J Zagrodnik, and C Mass. 2020. "Dual-Polarization Radar Retrievals of Coastal Pacific Northwest Raindrop Size Distribution Parameters Using Random Forest Regression." Journal of Atmospheric and Oceanic Technology, 37(2), 10.1175/JTECH-D-19-0107.1.

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