Spatiotemporal Variability of Saturn's Zonal Winds from Cassini Multi-Instrument Observations
Abstract
The strong zonal winds on the giant planets are one of the most amazing phenomena in our solar system. Here, Saturn's zonal winds are investigated with the long-term (2004-2015) observations recorded by three instruments aboard Cassini: the Composite Infrared Spectrometer (CIRS) (Flasar et al., 2004), the Imaging Science Subsystem (ISS) (Porco et al., 2004), and the Visual and Infrared Mapping Spectrometer (VIMS) (Brown et al., 2004). The VIMS 5-micrometer images can probe Saturn's relatively deep atmospheric layers around 1000-3000 mbar (Baines et al., 2005, 2009; Choi et al., 2009). We process the 5-micrometer images of Saturn's Northern Hemisphere (NH) recorded by the VIMS in 2015. The processed NH maps are further subjected to a cloud-correlating program to measure the zonal winds in the relatively deep layers. The preliminary comparison between the new measurements in 2015 and previous measurements in 2004-2007 (Choi et al., 2009) suggests that the zonal winds at 1000-3000 mbar decreased by about 100 m/s between 2004-2007 and 2015 in the northern equatorial region, whereas the relatively deep zonal winds have been essentially constant over time in the middle and high latitudes of the NH. We are processing more VIMS 5-micrometer observations to examine the temporal variations of the relatively deep zonal winds. In addition, the observations from the ISS (e.g., MT3 images) and CIRS (e.g., retrieved temperature for thermal winds) are being used to explore the temporal variations of the zonal winds at high altitudes (1-750 mbar). Finally, we will combine the observations from the three Cassini instruments (CIRS, ISS, and VIMS) to explore the vertical structures of Saturn's zonal winds and their temporal variations, especially in the equatorial region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.P31D..05L
- Keywords:
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- 5704 Atmospheres;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5706 Aurorae;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5724 Interiors;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5737 Magnetospheres;
- PLANETARY SCIENCES: FLUID PLANETS