The microwave absorption of SO2 in the Venus atmosphere

Microwave absorptivity by sulfuric acid in the Venus atmosphere: First results from the Venus Express Radio Science experiment VeRa

“…for the SO 2 contribution (Janssen and Poynter, 1981;Steffes and Eshleman, 1981;Fahd and Steffes, 1992;Suleiman et al, 1996), where a is the total absorptivity derived from Eq. (7) in dB/km, f the carrier frequency (GHz), p the pressure (Pa), T the temperature (K), and q is the number mixing ratio of the gas ðq CO 2 ¼ 0:965; q N 2 ¼ 0:035Þ.…”

X band model of Venus atmosphere permittivity

“… where N 0 is the Avogadro's number, d is the density in g/m 3 , M is the molecular weight in g, k is the Boltzmann constant, α T is the molecular polarizability, μ is the molecular dipole moment, g is the Kirkwood correlation factor that equals 1 for the gas phase. By knowing the permanent dipole moment = 1.63D [ Janssen and Poynter , 1981] (D is the unit ‘Debye’ for electric dipole moment, D = 3.33564 × 10 −30 C · m), the polarizability can be calculated from the above ε r ′ at T = 0°C and pressure of 1 atm. The dielectric constant and polarization of SO 2 at other temperatures and pressures are consequently known.…”

“…The SO 2 molecule is an asymmetric rotor with a rich rotational spectrum extending throughout the microwave region; therefore, the microwave absorption of SO 2 is significant. Janssen and Poynter [1981] provide a theoretical model describing this absorption, and Steffes and Eshleman [1981b] give a model based on the laboratory measurements simulating the temperature and pressure at the layer containing SO 2 in the Venus atmosphere. However, in the recent literature, Suleiman et al [1996] mention that the Steffes and Eshleman [1981b] model is not an optimal fit to the measured results at all frequencies and that the frequency dependence is not uniformly valid due to measurement errors.…”

“…The high atmospheric density resulting from high pressure and temperatures considerably impacts on electromagnetic wave propagation. Also both the clouds and the atmospheric gases cause significant absorption of the radio signals [ Janssen and Poynter , 1981; Kolodner and Steffes , 1998].…”