Saturn Zonal Wind Kinetic Energy Budget: Equatorial Superrotation and Mid-Latitude Jets from Cassini Cloud Tracking

This paper computes a quantitative budget for the atmosphere and its energy transport of Saturn from published spacecraft values, using a deliberately transparent calculation whose every step can be checked from the deposited script. The headline results are: equatorial_wind_m_s = 355; weather_layer_mass_kg = 1.07e+22; jet_kinetic_energy_J = 1.92e+25; equatorial_band_energy_J = 2.3e+26; combined_wind_energy_J = 2.49e+26; equatorial_band_area_percent = 34.2. The equatorial band, covering about a third of the surface area within the adopted layer, carries an energy comparable to the entire remaining circulation at its root-mean-square speed, because energy weights speed squared and the equatorial stream is several times faster than a typical jet. The combined energy is far below Jupiter's deep-wind budget, as expected for a budget restricted to the shallow weather layer; the comparison therefore measures the depth difference between what Cassini could see and what Juno's gravity could sense, not a claim that Saturn's deep winds are weak. The treatment states its inputs, its geometric and physical assumptions, and the sensitivity of each conclusion to those choices, so that the results function as a consistency test on the published values as much as a derivation from them. Where the computed budget agrees with independent determinations, the agreement corroborates both; where it strains, the strain identifies the input or assumption most likely to need revision.