Properly Resolving the Effective Measurement Area in a High-Fidelity Rain Measurement Device

Student: Christopher Blouin

Major: Physics

Mentors: Dr. Michael L. Larsen

Department: Physics and Astronomy

Properly Resolving the Effective Measurement Area in a High-Fidelity Rain Measurement Device

The 2-Dimensional Video Disdrometer (2DVD, manufactured by Joanneum Research) is a high-fidelity optical rain measurement device that utilizes two line-scan cameras for ground validation of satellite rain measurements. Recent work has shown that part of this instrument's sensing area can be temporarily rendered inaccessible due to obstacles on the internal optics of the instrument. Here, we present an algorithm to remove incorrectly recorded raindrops from the data record and re-adjust the effective area for all other drops while accounting for the reduced sensing area. Furthermore, to more accurately determine the effective area of the device, we account for the trapezoidal nature of the field of view and the subsequent varying pixel size. Over an entire combined data set from over 10 years of 2DVD data, these changes to the data record result in a 1.1 percent increase in overall rain accumulations. Furthermore, physical measurements from the 2DVD suggest an overall change to average effective area measurements by approximately 8 percent even before accounting for the trapezoidal field of view of each camera.