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Dual-Plane Optical Disdrometer

The University of Iowa LiDAR Group developed and built a new dual-plane optical disdrometer that is robust, calibration-free, and low-cost, and that also provides an accurate drop-size distribution.

The University of Iowa LiDAR Group developed and built a new dual-plane optical disdrometer that is robust, calibration-free, and low-cost, and that also provides an accurate drop-size distribution.

Acquiring better drop-size distributions of rainfall will improve our understanding of the spatial and temporal variability of rainfall. Therefore, a robust, calibration-free, low-cost instrument that provides an accurate drop-size distribution is required. The University of Iowa LiDAR Group developed and built a new dual-plane optical disdrometer that meets these criteria. Two sheets of laser light, vertically spaced by 1 cm, are produced by two 670nm laser beams passing through a collecting lens and culminating lens, respectively. The two sheets of laser light then pass through a convex lens located 20 cm from the lasers that focuses the light on a photo detector. A computer reads and stores the voltages at 10 kHz. The velocity, diameter, shape, and drop-size distribution of raindrops are extracted from the voltage measurements. We test our disdrometer’s robustness and accuracy of providing drop-size distributions with rainfall data collected in Iowa City, Iowa. Our distrometer is advantageous because it is simple, low-cost, and requires no calibration.

Last modified on February 16th, 2012
Posted on February 15th, 2012

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