vdis: Video Disdrometer

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

Active Instrument Locations

Facility Name Instrument Start Date
Graciosa Island, Azores, Portugal 2014-10-31
Central Facility, Lamont, OK 2011-02-28
Lamont, OK (Extended and Co-located with C1) 1999-12-31


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.

Matsui T, B Dolan, T Iguchi, S Rutledge, W Tao, and S Lang. 2020. "Polarimetric Radar Characteristics of Simulated and Observed Intense Convective Cores for a Midlatitude Continental and Tropical Maritime Environment." Journal of Hydrometeorology, 21(3), 10.1175/JHM-D-19-0185.1.
Research Highlight

Lawler M, D Draper, and J Smith. 2020. "Atmospheric fungal nanoparticle bursts." Science Advances, 6(3), 10.1126/sciadv.aax9051.
Research Highlight

Tokay A, L D’Adderio, D Marks, J Pippitt, D Wolff, and W Petersen. 2020. "Comparison of Raindrop Size Distribution between NASA’s S-band Polarimetric Radar and Two-Dimensional Video Disdrometers." Journal of Applied Meteorology and Climatology, 59(3), 10.1175/JAMC-D-18-0339.1.


Varble A, S Nesbitt, P Salio, E Avila, P Borque, P DeMott, G McFarquhar, S van den Heever, E Zipser, D Gochis, R Houze, M Jensen, P Kollias, S Kreidenweis, R Leung, K Rasmussen, D Romps, and C Williams. 2019. Cloud, Aerosol, and Complex Terrain Interactions (CACTI) Field Campaign Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-19-028.

Endo S, D Zhang, A Vogelmann, P Kollias, K Lamer, M Oue, H Xiao, W Gustafson, and D Romps. 2019. "Reconciling Differences Between Large‐Eddy Simulations and Doppler Lidar Observations of Continental Shallow Cumulus Cloud‐Base Vertical Velocity." Geophysical Research Letters, 46(20), 10.1029/2019GL084893.

Mason S, R Hogan, C Westbrook, S Kneifel, D Moisseev, and L von Terzi. 2019. "The importance of particle size distribution and internal structure for triple-frequency radar retrievals of the morphology of snow." Atmospheric Measurement Techniques, 12(9), 10.5194/amt-12-4993-2019.

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