3D Stereo Disdrometer

The 3D Stereo Disdrometer measures all kinds of particles such as drizzle, rain, snow, hail and mixed precipitation. Furthermore, it is also able to identify non-hydrometeors. Due to its three-dimensional particle detection ability, it will show a reduced error under windy conditions.
The acquisition comprises the types of precipitation, intensity, and size-speed-distribution. All measuring values are available for the user via Ethernet, RS485 interface and files on SD card.

In the basic version, the camera module housing is equipped with a temperature-controlled heater. Instruments are equipped with the temperature sensor. These values will also be available via the RS485 interface and Ethernet connection.
For sites with rough climates, a version with "extended heating" is also available.

The instrument is especially suited for application in the fields of:
• Meteorology
• Climatology
• Regenerative energy, wind power plants
• Traffic engineering, aviation, and navigation
• Hydrology
 
The3D Stereo Disdrometer essentially consists of a suitable light source and a stereo camera. The measurement volume is defined by the viewing angles of the cameras and the minimum and maximum distance to the cameras.


When particles pass through this measurement volume, they change the light signal registered by the cameras. The size of the particle is determined from the captured image area and the position of the particle in the measurement volume. The speed is calculated from the measured movement of the particle within a specified time interval. In addition, analysis of the image characteristics allows a distinction to be made between different types of particles such as rain, snow, hail, sleet, seeds, or insects.

The calculated data are memorized over one minute, and then transmitted via serial interface, Ethernet (TCP/­IP connection, up to 5 clients at a time) or store on the SD card as a file.
The type of precipitation is determined from the statistic proportion of all particles referring to diameter and velocity. These proportions have been tested scientifically (e.g. Gunn, R., and Kinzer, G.D., 1949, "The terminal velocity of fall for water droplets in stagnant air." J. of Meteorology, Vol. 6, pp. 243-248). In addition, the temperature is included in order to improve the identification.

The instrument is almost maintenance-free. Only the glasses of camera module head and LED pane should be cleaned, if necessary. For application in areas of extreme weather conditions (for example high mountains), we recommend a model with “extended heating”. By using a flash-memory the internal software can be updated any time via Ethernet connection.

Various ways for data output:
• Ethernet
• RS485
• Stored on an internal SD card