Search Publications
Diurnal variation of electron density in Saturn’s ionosphere: Model comparisons with Saturn Electrostatic Discharge (SED) observations
Galand, Marina; Moore, Luke; Fischer, Georg +2 more
Using the Saturn Thermosphere Ionosphere Model (STIM), we present a study of the diurnal variation of electron density, with a focus on comparisons with peak electron densities (NMAX) inferred from the low-frequency cutoff of radio emission due to lightning in the lower atmosphere, called Saturn Electrostatic Discharges (SEDs). It is de…
Cassini-UVIS observation of dayglow FUV emissions of carbon in the thermosphere of Venus
Gérard, J. -C.; Hubert, B.; Gladstone, G. R. +3 more
We analyze FUV spatially-resolved dayglow spectra obtained at 0.37 nm resolution by the UVIS instrument during the Cassini flyby of Venus. The intensities of the ultraviolet multiplets of carbon at 126.1, 156.1 and 165.7 nm are determined using a least squares fit technique applied to all dayglow spectra recorded by UVIS along the Cassini track. T…
First ever in situ observations of Venus' polar upper atmosphere density using the tracking data of the Venus Express Atmospheric Drag Experiment (VExADE)
Rosenblatt, P.; Häusler, B.; Svedhem, H. +3 more
On its highly elliptical 24 h orbit around Venus, the Venus Express (VEX) spacecraft briefly reaches a periapsis altitude of nominally 250 km. Recently, however, dedicated and intense radio tracking campaigns have taken place in August 2008, October 2009, February and April 2010, for which the periapsis altitude was lowered to the 186-176 km altit…
Spatial correlation of OH Meinel and O 2 infrared atmospheric nightglow emissions observed with VIRTIS-M on board Venus Express
Drossart, P.; Piccioni, G.; Gérard, J. -C. +1 more
We present the two-dimensional distribution of the O 2 a 1Δ-X 3Σ (0-0) band at 1.27 µm and the OH Δ v = 1 Meinel airglow measured simultaneously with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express. We show that the two emissions present very similar spatial structures. A…
Latitudinal distribution of HDO abundance above Venus' clouds by ground-based 2.3 µm spectroscopy
Matsui, H.; Iwagami, N.; Hosouchi, M. +2 more
The abundance of HDO above the clouds in the dayside atmosphere of Venus was measured by ground-based 2.3 µm spectroscopy over 4 days. This is the first HDO observation above the clouds in this wavelength region corresponding to a new height region. The latitudinal distributions found show no clearly defined structure. The disk-averaged mixi…
Observation of DCl and upper limit to NH3 on Venus
Krasnopolsky, Vladimir
To search for DCl in the Venus atmosphere, a spectrum near the D35Cl (1-0) R4 line at 2141.54 cm-1 was observed using the CSHELL spectrograph at NASA IRTF. Least square fitting to the spectrum by a synthetic spectrum results in a DCl mixing ratio of 17.8 ± 6.8 ppb. Comparing to the HCl abundance of 400 ± 30 ppb (Krasnopolsky …
Zonal winds at high latitudes on Venus: An improved application of cyclostrophic balance to Venus Express observations
Read, Peter L.; Mendonça, João M.; Wilson, Colin F. +1 more
Recent retrievals of zonal thermal winds obtained in a cyclostrophic regime on Venus are generally consistent with cloud tracking measurements at mid-latitudes, but become unphysical in polar regions where the values obtained above the clouds are often less than or close to zero. Using a global atmospheric model, we show that the main source of er…
UV spectrum of Enceladus
Noll, Keith S.; Clarke, John T.; Hendrix, Amanda R. +1 more
We present a far ultraviolet (FUV) spectrum of Saturn’s moon Enceladus from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). We have put upper limits on emission from C, N, and O lines in Enceladus’ atmosphere and column densities for the C lines assuming solar resonance scattering. We find these upper limits to be relati…
Improved luminosity model and albedo for Saturn
Mallama, Anthony
The globe of Saturn is brighter than previously reported as indicated by its absolute opposition magnitudes in the UBVRI band passes which are -7.080, -7.842, -8.914, -9.587 and -9.606, respectively. The geometric albedo in V is 0.501 and it peaks in the R filter at 0.567. The brightest apparent magnitude of the system in the V-band is -0.61 and t…
Vertical cloud structure of the 2009 Jupiter impact based on HST/WFC3 observations
Sánchez-Lavega, A.; Pérez-Hoyos, S.; Wong, M. H. +7 more
The impact of a body of unknown origin with Jupiter in July 2009 produced an intense perturbation of the planet’s atmosphere at the visible cloud levels. The vertical cloud structure was deeply affected by the presence of a strongly absorbing dense aerosol layer that was expanded steadily by advection in the local winds. We observed this phenomeno…