The HVPS measures the size, shape and concentration of precipitation size particles. It operates by taking a two-dimensional shadow digital picture of the particles that pass through a 4.5 x 20.3 cm laser light plane that is normal to the direction of aircraft flight. The sheet of light is imaged onto a linear array of 256 photo-elements, so that the HVPS has 200 µm pixel resolution when measured across the array. In order to keep the pixel resolution along the flight path constant, the system clock frequency is adjusted according to the detected True Air Speed (TAS) by the data system itself.
The maximum clock frequency for the HVPS is 240 kHz. The HVPS data recorded during this project has 400 m m resolution along the flight path.
