Fluctuations in Humidity, Temperature, and Horizontal Wind as Measured by a Subcloud Tethered-Balloon System

A system is described for measuring atmospheric temperature, humidity, and wind speed continuously and simultaneously at more than one level between 50 and 600 m above the ocean or land surface. The design of the system is presented. This consists of a modulator-transmitter unit which is suspended from a tether line supported by a balloon and controlled by a winch. Data are transmitted by radio link to a receiver-demodulator and recorder at the surface. Results are given which show that the system is capable of acquiring simultaneous time series of meteorological variables at two levels. This presents a viable, though not complete, method for acquiring time series data in a region of the atmosphere previously poorly sampled. The data presented suggest that turbulent mixing in this layer is governed by moist plumes on a scale of 100 m or more. Spectra of humidity are in good agreement with the Kolmogoroff minus-five-thirds law in the inertial subrange between 0.1 and 0.5 Hz. These spectra seem consistent with previous findings and support the suggested scale and role of the moist plumes in the turbulent transfer processes in the subcloud layer.