SBIR-STTR Award

In the proposed research the feasibility will be established for developing a low-cost expendable transducer mounted in a national weather service type radiosonde to measure vertical profiles of supercooled liquid water. The transducer is based upon a wire whose natural vibration frequency varies according to the amount of ice collected on the wire. The research will examine the effects on the results of variations in temperature, airflow, drop size distribution and, most importantly, of supercooled liquid water concentration. Two alternate forms of the transducer system will be used, on a small coil to sense the vibrations, the other, an optical sensing method. A series of tests and calibrations are proposed to determine the various effects being examined and to compare the supercooled liquid water concentrations derived from the two transducer forms and a standard method of measurement by a fast rotating rod. Various types of radiosonde systems will be surveyed to assess their appropriateness for use with the vibrating wire.

In the proposed research an expendable balloon-carried device for measuring supercooled liquid water in clouds will undergo final laboratory and field testing so that the device will be ready for operational use. Previous tests have shown that the expendable instrument is indeed a feasible way to obtain low cost measurment of supercooled liquid water in clouds. The proposed laboratory tests will be directed at confirming previous work and delineating conditions when the system may yield different results from independent laboratory measurements. In the field phase, comparisons between measurements made with the expendable device and with a passive microwave radiometer will be made during episodes of supercooled clouds. Such field tests will provide the basis for assessment as to the obtainability of quantitative information from the device. Other aspects of the research include a production phase wherein a hundred expendable units will be produced for crrel's use. A ground based receiver will also be modified to be compatible with the transmitted data from the expendable devices. Data received will be processed automatically to yield concentrations of supercooled liquid water versus altitude.