During the spring and spring and summer of 2002 researchers from institutions in the U.S., Canada, and France conducted an unique experiment to compare measurements of natural rain made with different type of disdrometers.  The instruments were collocated at the Iowa City Municipal Airport in Iowa City, I.A.  Other instruments at the site were a vertically pointing X-band radar, anemometer, and a wind profiler. 

Estimates of drop size distribution (DSD) are important for remote sensing of precipitation, both from ground-based weather radar as well as from space-borne platforms.  In particular, increasing our understanding of the small-scale variability of DSD, and therefore, several bulk characteristics of rainfall processes, has major implication for our interpretation of the remote sensing based estimates of precipitation and its uncertainty.   As new observational capabilities become available for collecting information on DSD, it is important to evaluate them against the known standards.  In DEVEX we evaluate two new types of optical disdrometers: Parsivel M300 made by PMTech AG (Germany) and the CEPT (France) Dual-Beam Spectropluviometer. 

The main goals of the experiment were:

1. Comparing new types of optical disdrometers to the standard types;
2. Measuring small-scale variability of DSD at spatial scales below 1 km, and temporal scales on the order of seconds;
3. Evaluating the ability of S-band and X-band vertically pointing Doppler radars to estimate profiles of DSD.
4. The project was funded by the home institutions of the participants.