Jovian Zonal Winds Revealed from Cassini/VIMS Observations

Abstract

Understanding Jupiter's zonal winds is crucial to unraveling the dynamics of its atmosphere. Over the last decades, multiple data sources and techniques have been used to study zonal winds in Jupiter. Here, we develop a correlation-based method for the near-infrared data from the Cassini spacecraft to investigate zonal winds at different altitudes. The new method uses Jupiter's rotation to scan the planet as it rotates, allowing retrieval of winds from the analysis of light-curves of specific pixels over the Jovian disc. The method allows the retrieval of winds at multiple wavelengths from the Cassini/VIMS spectral data despite the low spatial resolution and the non-uniform cadence of the data. By applying this method to two VIMS data cubes acquired on 15 January 2001 at 09:42 UT and 16 January 2001 at 03:22 UT, we reveal the zonal winds at five main latitudes using information from three different wavebands, as well as the wind vertical structure at the equator, showing significant vertical wind shear in the troposphere. The vertical wind shear we derived is weaker than as reported in previous studies, highlighting the intricate interactions among multiple dynamical processes in Jupiter's atmosphere and reflecting the complexity of its atmospheric circulation. Despite the uncertainty due to the low spatial/temporal resolution and non-uniform cadence of the Cassini/VIMS-IR spectral data, the new method established in this study maximizes the value of the Cassini/VIMS in understanding Jupiter's zonal winds. Further observations are essential to explore the underlying mechanisms in Jupiter's atmosphere.