| Name: | Soumyaneal Banerjee |
| Affiliation: | Vikram Sarabhai Space Centre |
| Conference ID: | ASI2025_629 |
| Title: | Sulfuric Acid and Sulfur Dioxide vapor concentrations in the lower atmosphere of Venus using the Radio Occultation Technique |
| Authors: | S. Banerjee 1, R. K. Choudhary 1, K. R. Tripathi 2, K. M. Ambili 1, A. A. Potdar 1, T. Imamura 2 |
| Authors Affiliation: | 1 Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum - 695022, India
2 The University of Tokyo, Kashiwa, Chiba - 277-8561, Japan |
| Mode of Presentation: | Oral |
| Abstract Category: | Sun, Solar System, Exoplanets, and Astrobiology |
| Abstract: | Radio Occultation (RO) experiments by the Akatsuki spacecraft have been used to probe the lower atmosphere of Venus and study the sulfuric acid vapors typically present between the altitudes of 35-50 km, below the Venus cloud deck. H2SO4 and SO2 are two of the major trace species found in the lower atmosphere of Venus. The notoriously high density and opacity of the Venus atmosphere make visible, IR and UV observations practically impossible below the cloud top region of 65-70 km. The stable X-band radio signal (~8.4 GHz) emitted by the transmitter of the Radio Science (RS) payload of the Akatsuki Spacecraft traverses the Venus atmosphere and suffers intensity loss and phase change. The loss in signal intensity occurs due to refractive effects and absorption by the Venus atmosphere. The primary X-band absorber is H2SO4 vapor. The signal attenuation due to refractive effects and absorption by the known X-band absorbers in Venus are subtracted from the total signal loss. The residual absorption loss, due to H2SO4 vapors, is then converted into mixing ratio values, thereby providing the vapor abundance in the region. A new signal processing algorithm has been used to derive the signal attenuation from the raw data files. Additionally, SO2 concentrations from 35-55 km region are also estimated considering our current understanding that H2SO4 vapor concentration decreases exponentially to zero above 50 km altitude, following its saturation vapor pressure curve. This provides the SO2 vapor concentration in the range of a few tens to a few hundred ppm, agreeing with the existing studies. |
