Abstract

While the theoretical limitations of optical array probes used for cloud particle measurements are well known, some details of actual field performance are undetermined. The response to particles in the 25–150-μm range is unresolved and the maximum information content is unknown. There also remains a major problem in the measurement of particle mass, since particle density and morphology is usually impossible to discern from the probe’s array shadow images. In an effort to resolve these problems, a SDL holographic system modified for cold weather operation was used in conjunction with a PMS 2D-C optical array probe to measure snow particles. The 2-D probe was modified to record only those particles which fell totally within its diode array; particle detection triggered a pulse which fired the holographic system's ruby laser. Experimental operations were conducted at the University of Wyoming’s Elk Mountain Observatory. This facility is a well-equipped mountaintop laboratory where a wide variety of ice particle habits occur naturally. Aircraft measurement conditions were duplicated in the observatory's wind tunnel; a cold room was also used. Holographic and 2-D data were successfully obtained in field conditions, laying the groundwork necessary for future complete calibration tests.

© 1985 Optical Society of America