cvi

Counterflow Virtual Impactor (CVI)

Schematic of CVI

Ambient gases and low inertia (smaller) particles are prevented from entering the CVI by the counter flow, while high inertia particles follow the sample flow to whatever instrumentation is downstream of the CVI. The distance from the tip of the CVI to the stagnation plane is a function of the flows and dimensions of the CVI and will determine the size of particles collected. (Schematic based on drawing from S. Tuckers MS thesis.)

The CVI at Åreskutan

Click on image to see larger view.

photos by J. Ogren

From left to right:

  • close up of CVI used in Sweden in 1989
  • CVI installed on rooftop sampling system in 1989
  • observatory on top of Åreskutan in Sweden showing CVIs used in 1986

  • A CVI during the AIRS-II field project


  • The Cloud Spectrometer and Impactor (CSI) incorporates a CVI inlet in front and a droplet scattering probe underneath. Photo taken from the C-130 cabin during the AIRS-II field program by Greg Kok.
  • Oregon State's (Cindy Twohy) standard CVI inlet on the side of the C-130

  • The Institut für Troposphärenforschung e.V. (IfT) airborne CVI, mounted on the Partenavia aircraft. Photo by Stephan Mertes.


  • Following the Areskutan CVI field experiment, NOAA/GMD has participated in various other field campaigns involving a CVI. Below are links to photos and/or webpages for these other CVI related campaigns.


    [Pt. Reyes,CA 2005 photos]
    [Åreskutan, Sweden, 2003 study]

    Counterflow Virtual Impactor (CVI)

    Counterflow Virtual Impactor References

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