Meteorological radiosonde interface for atmospheric ion production rate measurements

A disposable balloon-carried instrument, interfaced to a commercial meteorological radiosonde for measuring the atmospheric ion production rate, is described. The sensor used is a gamma-sensitive Geiger tube, operated at 550V bias, produced from a lightweight transformerless supply. The supply requires 15Vat10mA, and precision regulation is used to minimize the Geiger tube’s response to bias voltage changes. The supply was stable to 0.1% for supply voltage variations between 15 and 25V, and varied by less than 1% over temperatures from −53to25°C during an atmospheric ascent. A digital counter incremented with each Geiger tube event, and the instantaneous count value was telemetered over a radiolink, time-stamped on reception to obtain the count rate. The derived ion production rate profile agrees with a standard parametrization to 5%.