Radiative Transfer Simulations for the Observed Decrease of Radio Brightness Temperature of Venus With Increasing Decimeter Wavelengths: Possible Existence of a Reflective or Quasi-Conductive Subsurface

Antony, T and Suresh Raju, C and Mohan, N and Swarup, G and Oberoi, D and Krishna Moorthy, K (2022) Radiative Transfer Simulations for the Observed Decrease of Radio Brightness Temperature of Venus With Increasing Decimeter Wavelengths: Possible Existence of a Reflective or Quasi-Conductive Subsurface. In: Journal of Geophysical Research: Planets, 127 (1).

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Abstract

Radiometric observations of Venus have revealed a monotonic decrease of brightness temperature (Tb) in the decimeter wavelength regime. Such a decrease has also been independently reported by the observations using interferometric radio-telescopes, like the Very Large Array (VLA) in the USA and the Giant Metrewave Radio Telescope (GMRT) in India. In this work, we have carried out microwave radiative transfer (RT) simulations of thermal emission from the Venusian surface at decimeter wavelengths to examine the role of subsurface properties of Venusian regolith in the continuous reduction of Tb at the microwave-radiowave spectral domain. These simulations are compared against spectral microwave measurements by GMRT over a wide decimeter wavelength regime ranging from �23�128 cm. Good agreements are obtained for simulations that consider a two-layer Venusian surface (a low-loss medium overlaid over a reflecting/lossy medium) a situation that would arise if the subsurface layer has high dielectric properties due to the presence of semiconducting mineral assemblages such as pyrites, ferroelectric minerals, magnetite�hematite, magnetite�pyrite or magnetite�hematite�pyrite equilibrium assemblages. The thickness of the top layer, the possibilities of the formation of such layers and their geological and chemical evolutions are also discussed. © 2021. American Geophysical Union. All Rights Reserved.

Item Type:	Journal Article
Publication:	Journal of Geophysical Research: Planets
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to John Wiley and Sons Inc
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited:	14 Feb 2022 15:40
Last Modified:	14 Feb 2022 15:40
URI:	http://eprints.iisc.ac.in/id/eprint/71354

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