During the period from March till May of 1990 a series of synchronous measurements of the total ozone content have been conducted at the lake of Issyk–Kul', Kyrgyzstan and Thumba, India located at the same longitude of 77°W but at the latitudes 42.62° and 8.53°N, respectively. Measurements have been carried out using a highly precise instrumentation. A Brewer No. 044 spectrophotometer of the Scientific–Production Union "Taifun" and the ozonometric instrument SFSU of Kyrgyz State University used in these measurements were mutually verified and compared with the international etalon instrument "Brewer No. 017". A statistically proved correlation between the variations of daily mean values of the total ozone content over the lake of Issyk–Kul' and the solar radiation flux at the 2800–MHz frequency has been revealed. In the case of measurement data obtained in tropics such a correlation cannot be considered statistically proved.