CAROb cloud condensation nuclei counter

A single-chamber cloud condensation nuclei counter from Droplet Measurement Technologies (DMT) is situated next to the micropulse lidar inside the penthouse lab. CCN concentrations (the fraction of aerosol that can become droplets in ambient clouds) are measured at supersaturations established by applying a temperature gradient along a continuous, laminar air flow, making use of dissimilar heat and water vapor diffusivities. The lowest size bin spans 0.5-0.75 micron. We have nominally set the supersaturations within the CCN-100 at 0.2, 0.4 and 1.0%, at a 1Hz sampling rate. The instrument has been running continuously since early December, 2011.