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Optical Disdrometer ODM470

Instrument to measure precipitation at wind-exposed sites

key benefits

  • the rain drop or snow particle measurement is independent of the incidence angle due to the cylindrical shape of the optical volume
  • the optical volume always adjusts perpendicular to the local wind by aid of a wind vane
  • the high dynamic range allows resolving 128 size bins with logarithmic increase in size from 0.1 to 22 mm in diameter
  • the system is fully automatic and requires minimal maintenance

Description

Precipitation measurement over the global oceans onboard moving ships is a notoriously difficult task. Gauge based systems are prone to large undercatch errors due to fluctuating high wind speeds and flow distortion. While the errors are large for rainfall, the estimation of snowfall and mixed-phase precipitation is impossible. In addition to the precipitation accumulation, precise information about the particle size distributions for rain and snow are required for various tasks, e.g. calibrating spaceborne radars or to improve understanding of the microphysical properties of precipitation. Thus, systematic high quality oceanic in-situ precipitation measurements are requested on an international science level and are essential for improved understanding and validation of hydrological processes in satellite, re-analysis and model data.
The automated optical disdrometer systems (ODM470) is capable of measuring precipitation occurrence, intensity and accumulation through minute-based particle size distributions discriminated for rain, snow and mixed-phase precipitation. The ODM470 was especially designed for shipboard operation under high and frequently varying wind speeds, flow distortion conditions and rough sea states. 


Scope of supply

  • ODM 470 measuring unit with wind vane
  • Central processing and power supply unit with LCD-display

Options available

  • Input for external wind speed and or precipitation yes/no
  • precipitation sensor upgrade kit
  • wind speed sensor
  • mast mountings
  • cable

Technical Data

Power consumption0.30 A without IRSS 88
0.38 A with IRSS 88
Power Supply100…230 VAC
approx. 20 W
Bins / Classes0.5 – 22 mmlog scale
 0.5 mm diameternoice equivalent
128 classes
Dimensions9.5 kgweight
60 cmheight
60 cmwidth
60 cmlength incl. vane