Research conducted over the years for the First ISCCP Regional Experiment (FIRE) has led to major improvements in our understanding of the role of clouds in the global climate system. In the spring of 1998, FIRE conducted Phase III of the program in conjunction with the Surface Heat Budget of the Arctic Ocean (SHEBA). The goal of the FIRE Arctic Cloud Experiment (FIRE.ACE) was to study a variety of arctic cloud systems under spring and summer conditions.
A new instrument, the cloud particle imager, was deployed on the National Center for Atmospheric Research (NCAR) C-130 during FIRE.ACE in both May and July of 1998. The cloud particle imager (CPI) casts an image of a particle on a solid-state, one million pixel CCD camera by freezing the motion of the particle using a 20 ns pulsed, high power laser diode. Upstream lasers precisely define the depth-of-field so that at least one particle in the frame is almost always in focus. This eliminates out-of-focus sizing errors that occur in the conventional 2D-C imaging probes and allow for resolution to distinguish phase of particles < 200 µm.
In this paper, we present a summary of the particles imaged in various cloud types during the FIRE.ACE experiment. Images, size distributions and discrimination of ice phase from water phase data will be presented for mixed phase and all water boundary layer clouds, mid-level clouds and cirrus. While most data were obtained over the SHEBA ice station during Phase I and II of FIRE.ACE, data taken during the ferry flights over Alaska will also be included.