Results from the professional-amateur collaboration to investigate the Cloud Discontinuity phenomenon in Venus’ atmosphere

<p>The cloud discontinuity of Venus is a planetary-scale phenomenon known to be recurrent since, at least, the 1980s. It was initially identified in images from JAXA&#8217;s orbiter Akatsuki.&#160; This disruption is associated to dramatic changes in the clouds&#8217; opacity and distribution of aerosols and is interpreted as a new type of Kelvin wave. The phenomenon may constitute a critical piece for our understanding of the thermal balance and atmospheric circulation of Venus. The&#160; reappearance on the dayside middle clouds&#160; four years after its last detection with Akatsuki/IR1 is reported in this work. We characterize its main properties using exclusively near-infrared images from amateur observations for the first time. The discontinuity exhibited temp&#959;r&#1072;l variations in its zonal speed, orientation, length, and its effect over the clouds&#8217; albedo during the 2019/2020 eastern elongation in agreement with previous r&#1077;&#961;orts. Moreover, amateur observations are compared with simultaneous observations by Akatsuki UVI and LIR confirming that the discontinuity is not visible on the upper clouds&#8217; albedo or thermal emission. While its zonal speeds are faster than the background winds at the middle clouds, and slower than winds at the clouds&#8217; top, it is evidencing that this Kelvin wave might be transporting momentum up to upper clouds.</p>