Sulfuric acid in the Venus atmosphere by radiooccultation data

The results of determination of cm-radiowaves absorption in radiooccultation of the Venus atmosphere using Venera-15 and -16 satellites are presented. Integral absorption of radiowaves of λ=5 cm range at the height of 61 km is -2.4 dB, at the height of 55 km it equals -0.6 dB, and at the height of 47 km it reaches -5.8 dB. Data on absorption of λ=15 cm and 13 cm range radiowaves for 40-70 km heights obtained using Pioneer-Venera and Venera-15 and -16 satellites are presented. It is shown that radiowave absorption is caused by vapours of the sulfuric acid. Distribution of vapours of the sulfuric acid at 39-53 km heights is found. At 39-44 km heights content of the sulfuric acid vapours depends weakly on the height and equals 37±7 ppm. When increasing the height over the surface of the Venus from 45 to 53 km the H2SO4 vapour content decreases as far as the height diminishes, for 47 km height it equals 20±5 ppm