DPS 2001 meeting, November 2001
Session 9. Cassini and Galileo at Jupiter Posters
Displayed, 9:00am Tuesday - 3:00pm Saturday, Highlighted, Tuesday, November 27, 2001, 5:00-7:00pm, French Market Exhibit Hall

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[9.04] Cassini CIRS Observations of Thermal Waves on Jupiter

R.K. Achterberg (SSAI), B.J. Conrath (Cornell U.), F.M. Flasar, A.A. Simon-Miller (NASA GSFC), C.A. Nixon (U. Md.), B. Bezard (Meudon Obs.)

During early January, 2001, four global mapping sequences of Jupiter were obtained using the Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft. Spectra were obtained over the entire globe in the wavenumber range from 600\,cm-1 to 1400\,cm-1 with a spatial resolution of 3 cm-1 and a spatial resolution of approximately 3\circ of great circle arc. Spectra with emission angles less than 75\circ were inverted by a constrained linear inversion method to obtain temperatures in the upper troposphere (100\,mbar -- 400\,mbar) and stratosphere (1\,mbar -- 10\,mbar). Deviations of the temperatures from the zonal mean for each of the maps were grouped into 5 degree latitude bins, and a Lomb-Scargle periodogram analysis applied to each latitude bin for pressures of 214, 10, 3, and 1\,mbar. For significant waves, amplitude and phase as a function of latitude are determined by least-squares fitting.

In contrast to results from Voyager IRIS maps, which were dominated by zonal wavenumber 1 (e.g. Magalhães et al. Icarus, 88, 39--72, 1990), the Cassini maps are dominated by zonal wavenumber 2, with wavenumbers~1 through~4 statistically significant at various latitudes. Significant waves are also seen at higher wavenumbers, particularly wavenumber~10 near the equator at 10\,mbar, and wavenumber~14 around 15\circN at 214\,mbar. With the exception of wavenumbers~1 and~2 near 30\circN, there appears to be very little correlation of wave features at the different pressure levels examined.

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