A New Continuous Flow Diffusion Chamber for Airborne Measurement of Natural Ice Nuclei over Japan

We built a Continuous Flow Diffusion Chamber (CFDC) based on the design of Rogers et al. (1988) at Colorado State University, USA and have improved it to operate fully automatically. When a new device was developed, it was necessary to satisfy the following requirement equipped with the aircraft. 1) Size of rack and lightening that small size aircraft can also install. 2) Simplification and leake measures of passage control system of sample air. 3) Labor saving of electric power used. 4) Efficiency improvement of observation by automatic measurement procedure. The rack that has divided into two for the main body and the control (A:1,650H 785W 600D, 190Kg, B:1,250H 560W 450D, 100Kg) is consolidated in one for the aircraft (1,045H 730W 450D, 115Kg, The highest point is 1,316mm) and has been improved more compactly. The chamber puts on the direction of right and left both and can substitute it according to the request of the aircraft for the observation. Moreover, the compressor and the air pump with a large weight are designed in the rack so that the barycentric position may stabilize low. Taking the sample air is shared the entrance with the particle measurement equipment such as OPC and CCNC with the heater addition inlet, decelerates the surrounding air, is introduced inside the aircraft, and diverges from the manifold. Sample air (1L/min) can be continuously taken, and activation Spectrum of the ice nuclei be acquired while changing the degree of supersaturation of each preset temperature. Moreover, vertical distribution of the number concentration of ice nuclei can be obtained by measuring it while keeping the temperature and the degree of supersaturation constant when the height of the aircraft has changed. It is scheduled to install in the aircraft after various performance trials and enough adjustments are done and to face the observation in the future.