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Space Weather Effects on Venus

Presentation #502.04 in the session Venus I (Oral Presentation)

Published onOct 23, 2023
Space Weather Effects on Venus

On Venus, the majority of ions produced in the atmosphere arise from cosmic ray collisions [1]. The maximum cosmic ray collision rate occurs within the optically thick cloud layer which shrouds Venus’ surface [1]. We currently know very little about the processes which govern the cloud microphysics here. Since a large number of ions are generated in the cloud layer, it is sensible to assume that there may be important charge-based processes present. We would thus assume that any perturbations to the incoming cosmic ray counts would propagate into perturbations to the cloud layer itself. These perturbations to the cosmic ray flux may take the form of space weather events, such as Forbush decreases or solar energetic particle events.

The link between cosmic rays and cloud layers has previously been investigated for other planetary atmospheres. Previous studies have shown that cosmic rays can affect the albedo of the ice giants through the process of ion induced nucleation [2]. This process occurs when cloud droplets form directly onto an ion, and requires very high supersaturations of vapour for it to be possible. As such, this process is not possible naturally on Earth, however it is believed to be possible within Venus’ atmosphere [3]. Additionally, a previous Earth based study has investigated the effects that Forbush decreases can have on the clouds on Earth [4].

We have used similar methods as those used for Earth and the ice giants to investigate any effects that space weather can have on Venus. In order to observe the effects on Venus, albedo data for the upper cloud layer was used. From this investigation, it is clear that cosmic rays are able to affect Venus’ albedo; Following several cosmic ray perturbations, the albedo was noticeably increased, and additionally, common periodicities were found between the albedo and the charged particle count rates recorded by several detectors. We have yet to identify the mechanism by which cosmic rays are able to affect the albedo of Venus, however this is an important first step in determining the effects that these space weather events can have.

References:

[1] T.A. Nordheim et al. (2015). Icarus, 80-86. [2] K.L. Aplin and R.G. Harrison (2017). Geophysical Research Letters, 12083-12090. [3] K.L. Aplin (2006). Surveys in Geophysics, 63-108. [4] R.G Harrison, M.H.P. Ambaum (2010). Journal of Atmospheric and Solar-Terrestrial Physics, 1408-1414.

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