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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.

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

images by J. Ogren

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/GML has participated in various other field campaigns involving a CVI. Below are links to images and/or webpages for these other CVI related campaigns.


[Pt. Reyes,CA 2005 images]

Counterflow Virtual Impactor (CVI)

Counterflow Virtual Impactor References

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