Emitted power of Jupiter based on Cassini CIRS and VIMS observations

Abstract

The emitted power of Jupiter and its meridional distribution are determined from observations by the Composite Infrared Spectrometer and Visual and Infrared Mapping Spectrometer onboard Cassini during its flyby en route to Saturn in late 2000 and early 2001. Jupiter's global‐average emitted power and effective temperature are measured to be 14.10 ± 0.03 Wm −2 and 125.57 ± 0.07 K, respectively. Jupiter's 5 μ m thermal emission contributes 0.7 ± 0.1% to the total emitted power at the global scale, but it can reach 1.9 ± 0.6% at 15°N. The meridional distribution of emitted power shows a significant asymmetry between the two hemispheres with the emitted power in the northern hemisphere 3.0 ± 0.3% larger than that in the southern hemisphere. Such an asymmetry shown in the Cassini epoch (2000–2001) is not present in the Voyager epoch (1979). In addition, the global‐average emitted power increased 3.8 ± 1.0% between the two epochs. The temporal variation of Jupiter's total emitted power is mainly due to the warming of atmospheric layers around the pressure level of 200 mbar. The temporal variation of emitted power was also discovered on Saturn. Therefore, we suggest that the varying emitted power is a common phenomenon on the giant planets.