Mapping Jupiter's Latitudinal Bands and Great Red Spot Using HST/WFPC2 Far-Ultraviolet Imaging

Abstract

Jupiter's low and mid-latitudes are examined using ultraviolet (UV) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994-1997. Effective atmospheric pressures probed by the F160W, F218W, and F255W are estimated at 100, 165, and 370 mbar, respectively, at low latitudes. Far-ultraviolet images of Jupiter taken with the F160W filter reveal bright and dark latitudinal bands at low and mid-latitudes. These bands were found to be correlated with the zonal winds; the bright bands are at latitudes of subsidences, and the dark bands at upwellings. The sense of this correlation is opposite to that seen in visible images of Jupiter where the bright zones are located over upwellings, and dark belts over subsidences. The locations of the dark bands seen in the F160W images are consistent with enhanced concentrations of NH3 and/or aerosols in the upwellings near the tropopause. Anticyclonic ovals, like the Great Red Spot, are regions of upwellings, and also appear dark in the F160W images. Temporal variations were also observed in the contrast of the low-latitude bands. An increase in the contrast of the low-latitude bands appeared to coincide with a visible wavelength broadening of the North Equatorial Belt that occurred in early to mid-1996. Changes at mid-southern latitudes were observed in the aftermath of the SL-9 impacts in July 1994.