My research is related to atmospheric aerosols and aerosol/cloud interactions, with an emphasis on airborne measurements. I'm interested in the indirect effect (through clouds) of aerosol particles on climate, and take measurements of CCN cloud condensation nuclei (CCN) and ice nuclei in clouds. I'm also involved in airflow analysis of airborne instrumentation and work on projects for the Research Aviation Facility at the National Center for Atmospheric Research.

One of the instruments I use, the counterflow virtual impactor (CVI), is used for cloud physics and chemistry studies. The CVI is an NCAR instrument and can be made available to the community by request. Here are the CVI aircraft mounting requirements (slightly out of date; contact me for updated info). A new version of the CVI optimized for measurement of cloud condensed water content has been developed in cooperation with Droplet Measurement Technologies (DMT) through an NSF STTR grant. A Powerpoint poster describing this instrument can be found here. These two papers describe in-situ and wind tunnel measurements of condensed water content using a CVI:

In-situ measurements
Wind tunnel measurements

Some CVI and CCN results sampling tropical cumulus in the Indian Ocean in INDOEX can be found in this 2001 JGR paper. I am also submitting a paper describing organic CCN found in this region. We are continuing our work on tropical cumulus in the Rain in Cumulus over the Ocean (RICO) experiment. In DYCOMS-II, we investigated relationships between aerosol concentration and microphysical and radiative properties of marine stratocumulus clouds--JGR paper in press. We also study mixed phase clouds in LAKE-ICE and AIRS-II and have reported on high droplet charge found in these clouds link. The National Science Foundation supports these studies.

I am also interested in convection, anvil cirrus and new particle formation near convection. This 2002 JGR paper reports on one of the largest particle nucleation events ever detected in the upper troposphere. We study ice nuclei using electron microscopy; our contrail analysis can be found here. A paper on results from thunderstorm anvils in CRYSTAL-FACE is forthcoming and an early Powerpoint presentation may be found here. NASA supports these studies.

Go to John Ogren's CVI pubs page
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