Forward Scatter Sensor FD70

Features

• Visibility up to 100 km (62 mi)

• Precipitation type identification,

intensity, and accumulation

• Droplet size distribution and

reflectivity

• Exceptional precipitation

detection sensitivity

• Superior liquid/frozen

differentiation

• Look-down geometry to minimize

measurement disturbances

• Enhanced visibility measurement

in sand dust conditions

Vaisala Forward Scatter Sensor FD70 combines forward scatter and optical

disdrometer technologies. FD70 sets the standard in precipitation identification and

quantification, providing best-in-class visibility determination.

Innovative technology

Novel use of a single thin light sheet

instead of the conventional light cone

results in high detection sensitivity,

enabling scatter-property analysis of

each single particle and allowing

detection of even the smallest drizzle

droplets. Particle size and fall speed

distributions provide additional

information, enhancing precipitation

type identification.

The receiver measures forward scattered

light at an angle of 42° with a very high

sampling rate and powerful signal

processing. Measurement arrangement

and method is patented.

Visibility measurement

FD70 forward scatter technology

provides the most representative

extinction coefficient (EXCO)

determination possible. Scatter-property

analysis reliably calculates the visibility-

reducing effect of precipitation, allowing

meteorological optical range (MOR)

reporting in the most challenging

conditions. FD70 covers all application

needs, including measurement

performance and capability

requirements for runway visual range

(RVR).

Precipitation measurement

Due to its innovative technology, FD70

reliably detects and identifies

precipitation types that have been

challenging for conventional

technologies.

Present weather identification 1) 2)

• Drizzle

• Rain

• Snow

• Snow grains

• Ice crystals

• Ice pellets

• Freezing drizzle

• Freezing rain

• Snow pellets

• Hail

• Fog

• Freezing fog

• Mist

• Haze

• Dust

1)

Optional

2) In addition to listed types, reports a

variety of mixed precipitation types

Reliable in all weather

FD70 has multiple features to ensure

reliable operation even in extreme

weather conditions. Effective hood

heating and proven look-down geometry

protect the sensor windows against

external disturbances. These are

complemented with independent optical

path monitoring and window

contamination compensation.

Self-diagnostics and modular design

enable short service times. Redundancy

of data communication is available for

critical cases such as airport use.

FD70 complies with ICAO, FAA, and

WMO requirements and uses WMO and

NWS weather codes in reporting.

Calibration traceability

To ensure specific visibility and rain

performance, Vaisala continuously

compares calibrated FD70 units against

reference sensors in the Vaisala outdoor

test field. Every delivered unit can be

traced back to this set of calibrated

reference sensors.