On the day of release, an interface board (A) is added to the O3 sensor, thus providing the connection between the ozonesonde and the specially modified radiosonde. The radiosonde transmits aerological data, and together with LORAN-C navigational signals, provides data for computation of upper winds, and these data are transmitted using normal 403 MHz radiosonde receivers to ground equipment located at the Station. The current generated by the presence of O3 is measured and transmitted through the radiosonde via the interface.