Electric conductivity and electric field in the stratosphere: Middle-latitude balloon flight results

Electric field and conductivity measurements were obtained for two high-alt itude balloon flights between Italy and Spain in 1989 and 1990. The high al titudes of these flights, 35 and 38 km, allowed us an opportunity to explor e the electrical parameters of the upper stratosphere at midlatitudes and t o extend the validity of earlier models to nearly 40 km. These new electric field and conductivity data are compared to similar data collected by many other groups. Our data are shown to be best represented by an extrapolatio n of the empirical model of Holzworth [1991] and therefore can be seen as e xtending the region of validity for his model from its upper altitude of 28 km by an additional 10 km to 38 km altitude. The possible influence of pho toelectric emissions in the results is also discussed.