Development of a High-Resolution Differential Temperature Sensor for CT2 Measurements

A persistent data collection site for characterizing parameters important for atmospheric propagation of electromagnetic waves has been established in Hazel Green, AL. This includes aerosol optical characteristics and the refractive index structure function (Cn2), which can be estimated using the structure function for temperature (CT2). To complement and evaluate existing in situ and ground-based measurements of CT2, and to support numerical modeling efforts, in situ, profile measurements of CT2 in the lower atmosphere are required. For this purpose, we have developed a high-resolution differential temperature sensor (DTS) that can be used in balloon-borne or UAS systems. This instrument measures differential temperature data at up to 200Hz temporal resolution using custom-built 5um platinum resistance temperature detectors (RTD) capable of temperature resolutions of 10^-4K. The DTS utilizes a Wheatstone bridge circuit for sensing the differential temperature for a specified separation. The temperature structure function (CT2) can be directly estimated from this measurement, and paired with other environmental measurements on board, to compute Cn2 along the flight path. This presentation will discuss the instrument's design and initial results from ground validations and deployment on various flight systems.