European Facility For Airborne Research

European Facility For Airborne Research May 17, 2022, 05:32

Instrument: Counterflow Virtual Impactor

Name Counterflow Virtual Impactor
Manufacturer University of Stockholm / Met Office developed
Operated by METOFFICE
Operated onboard

Instrument type

Name Counter-flow Virtual Impactor (CVI)
Acronym Counter-flow Virtual Impactor

Principle of operation

Measured parameter
Operating principle

Sample arm has heated dry air blowing OUT of it into airstream. Location of flow stagnation plane within intake determines minimum aerodynamic size of particles that can enter. Liquid or ice cloud particles enter intake, where water evaporates leaving cloud drop residual and water vapour.

Measurement(s) Aerosol

Dimension and weight

External dimension 3 double 19 inch racks required, plus specialised air inlet mounted externally
Weight 110.0


Operating mode In situ






Sample flow splits to several separate instruments that currently include:
- PMS PCASP (0.1-10 micron diameter)
- TSI 3010 condesnsation particle counter
- filter samples
- Lyman-alpha absorption hygrometer.
Data recorded on internal PC.

Operational restriction

The siting and orientaton of the sample arm, is critical to the operation of this instrument.

Operational requirements

Sample arm/inlet needs to be removed or blanked off if not required, as probe tip very delicate. Required dedicated person to operate instrument.

Certification approvals

Approved by CAA for use on BAe 146-301.

Additional information

Available from Met Office.

Access, host and processing


From Met Office

Could also fit on any aircraft having the following characteristics

General description

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