A Laser Disdrometer for All Types of Precipitation – OTT Parsivel²

The OTT Parsivel2 is a cutting-edge laser disdrometer that measures all kinds of precipitation. The Parsivel2 detects both the size and velocity of falling particles, categorizing them into one of 32 distinct size and velocity classes. The raw data is used to quantify the form, quantity, severity, and kinetic energy of the precipitation, as well as its accessibility and radar reflectivity.

  • Interface: SDI-12 / RS-485, pulse
  • Measurement technology: Laser optical
  • Product Highlights: Simultaneous measurement of 32 classes for particle sizes and velocities
  • Parameters measured: Precipitation form, intensity, drop size distribution, radar reflectivity


  • Accurate - The actual dimensions and speed of every precipitation particle that travels through the measurement area are noted, and all applicable meteorological parameters are sourced from these measurements.
  • Durable - Constant and detailed precipitation information in all environmental conditions with incorporated overvoltage protection
  • Maintenance-free - No moving parts or a collection bucket, unlike tipping bucket rain gauges
  • Easy-to-use - Incorporated USB port configuration and online monitoring for simple PC data review with OTT ASDO user software
  • Energy-efficient - Economical electronics and galvanically separate, controllable head heating, giving a power supply that is flexibly designed with minimal power consumption

Example of Use

  • Erosion Modeling - Kinetic precipitation energy calculated by the Parsivel2, paired with other parameters like ground state or relief, offers a key input for erosion models.
  • Early Flood Warning - When combined with water level sensors, the Parsivel2 is the central component in an initial flood warning system.
  • Monitoring Road Conditions - Precipitation amount and composition are united with general visibility measurements to offer an accurate picture of road conditions.
  • Precipitation Measurement - Comprehensive precipitation measurement comprising particle size, volume, and intensity. Precipitation size and type are each calculated into one of 32 classes, as specified by the World Meteorological Organization (WMO).

Laser Disdrometer for All Types of Precipitation

Image Credit: OTT HydroMet GmbH

Technical Data

Source: OTT HydroMet GmbH

Optical sensor, laser diode
Wavelength: 650 nm
Output power (peak): 0.2 mW
Laser Class: 1 (IEC/EN 60825-1:2014)
Measuring surface (W x D): 180 x 30 mm (54 cm2)
Measuring ranges
Particle size: liquid precipitation: 0.2 ... 8 mm
solid precipitation: 0.2 ... 25 mm
Particle velocity: 0.2 ... 20 m/s
Classification: 32 size and 32 velocity classes
Measurement accuracy 1): ± 1 size class ( 0.2 ... 2 mm)
± 0.5 size class ( > 2 mm)
Types of precipitation: 8 precipitation types (drizzle, drizzle/rain, rain, mixed rain/snow, snow, snow grains, sleet, hail)
Reports: WMO 4680/4677 (SYNOP),
4678 (METAR/SPECI) and NWS tables
Differentiation of precipitation types: drizzle, rain, hail, snow > 97%
(compared to a weather observer)
Snow depth intensity (volume equivalent)
Precipitation intensity: 0.001 ... 1200 mm/h
Accuracy 1): ± 5% (liquid) /± 20% (solid)
Radar reflectivity Z: - 9.999 ... 99.999 dBz
Kinetic energy: 0 ... 999.999 J/(m2h)
Visibility in precipitation (MOR): 0 ... 20.000 m
De-icing protection: Microprocessor controlled heating
Power supply
Power supply electronics: 10 ... 28 V DC, reverse polarity protection
Power consumption
Power consumption electronics: 65 [email protected] VDC / typ. 1.6 W
Power consumption window heater: Max: 4 [email protected] VDC / [email protected] VDC;
Min: 2 [email protected] VDC / [email protected] VDC
Heating capacity sensor heads: 50 [email protected] VDC;
100 [email protected] VDC
Interfaces (configurable2)): RS-485 for all values incl. spectral data (EIA-485; 1,200 ... 57,600 Baud)
SDI-12 for calculated values
USB for PC connection (configuration and service)
Output relay for pulse output of the precipitation amount in 0.1 mm/pulse with max. 2 Hz pulse rate
Physical Information
Weight: max. 6.4 kg
Dimensions (H x W x D): 670 x 600 x 114 mm
Environmental conditions:
Temperature range: - 40 ... +70 °C
Relative humidity: 0 ... 100%
Protection: IP65, resistant to salt spray
Lightning protection: integrated
Installation: 2 inch pipe, Ø 50 ... 62 mm
Standards: EN 61326-1: 2013, CE compliant
2014/30/EU, CE compliant


1) Proof under laboratory conditions using an OTT test system with reference particle simulation of 0.5 mm, 1.0 mm, 2.0 mm and 4.0 mm
2) ASDO configuration software supplied (basic version)

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