Instrumentation for Water Vapor Measurements for Radiosondes

51137-98-I Instrumentation for Water Vapor Measurements for Radiosondes--Yankee Environmental Systems, Inc., 101 Industrial Boulevard, Turners Falls, MA 01376-1608; (413) 863-0200 Mr. William M. Stein, Principal Investigator Ms. Cynthia A. Cote, Business Official DOE Grant No. DE-FG02-98ER82715 Amount: $75,000 Current sensors for measuring humidity on weather balloons are generally considered inadequate for supporting vital climate research efforts. This project will investigate a new water vapor sensor suitable for use on balloon-borne radiosondes. The proposed approach corrects several deficiencies found in current balloon-borne water vapor sensors, including inadequate accuracy, limited temperature operating range, and slow speed of response at low temperatures. The approach couples a servo loop system to a standard humidity sensor. By controlling the temperature of the sensor in relation to ambient humidity, the sensor can be forced to operate at a constant humidity. This means that water vapor no longer needs to migrate in and out of the sensor, dramatically improving the sensor response time. Phase I will bench test several candidate sensors in the servo configuration. The bench tests involve four main tasks: 1) building several prototype assemblies with a heat sink, thermoelectric (Peltier) device, and sensor, 2) prototyping the control electronics, 3) chamber testing the sensor assemblies over a wide range of temperatures and humidities, and 4) analyzing and reporting the results. Commercial Applications and Other Benefits as described by the awardee: The atmospheric physicist should have a greatly improved sensor for water vapor measurement. In addition, many industrial processes require monitoring of water vapor in the form of dew/frost point or relative humidity, resulting in a large number of potential commercial applications._