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Variable winds on Venus mapped in three dimensions
Baines, K. H.; Hueso, R.; Sánchez-Lavega, A. +9 more
We present zonal and meridional wind measurements at three altitude levels within the cloud layers of Venus from cloud tracking using images taken with the VIRTIS instrument on board Venus Express. At low latitudes, zonal winds in the Southern hemisphere are nearly constant with latitude with westward velocities of 105 ms-1 at cloud-top…
Characteristic size and shape of the mirror mode structures in the solar wind at 0.72 AU
Russell, C. T.; Zhang, T. L.; Glassmeier, K. -H. +10 more
We investigate the structure of mirror modes in the solar wind at 0.72 AU using Venus Express magnetic field measurements. The mirror mode structure is identified as the presence of magnetic depression or magnetic ``holes'' in the solar wind with little or no directional change across them. We determine the characteristic size and shape of these s…
Surface brightness variations seen by VIRTIS on Venus Express and implications for the evolution of the Lada Terra region, Venus
Drossart, Pierre; Piccioni, Giuseppe; Helbert, Jörn +3 more
Venus Express is since April 11, 2006 in orbit around Venus. VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) has started only hours after orbit insertion to collect an immense and unique data set. Of special interest is the wavelength range from 1-1.5 microns which includes the ``atmospheric windows''. By averaging several hundred multi…
Venus Express observes a new type of shock with pure kinematic relaxation
Zhang, T. L.; Balikhin, M. A.; Gedalin, M. +2 more
Collisionless shocks are present in the vicinity of many astrophysical objects such as supernova remnants, space jets, stars and planets immersed in the supersonic flow of stellar winds. Understanding the shock structure is crucial for understanding the processes of the redistribution of the upstream flow energy into accelerated particles and form…
Distribution of the O2 infrared nightglow observed with VIRTIS on board Venus Express
Hueso, R.; Sánchez-Lavega, A.; Erard, S. +5 more
We present characteristics of the statistical horizontal distribution of the O2 infrared nightglow over most of the southern hemisphere observed with the VIRTIS instrument over a period spanning nearly 11 months of low solar activity. We show that the distribution is inhomogeneous with the regions of brightest emission reaching ~3 MegaR…
First identification of mirror mode waves in Venus' magnetosheath?
Zhang, T. L.; Glassmeier, K. -H.; Baumjohann, W. +3 more
In this paper first time observations of mirror mode like structures in Venus' magnetosheath are presented. Using magnetometer data from the Venus Express spacecraft it is shown that in two regions in the Venusian magnetosheath strong compressional waves exist, which propagate nearly perpendicular to the ambient magnetic field. They are most likel…
First upstream proton cyclotron wave observations at Venus
Russell, C. T.; Wei, H. Y.; Zhang, T. L. +3 more
The escape of particles from planetary atmospheres, especially hydrogen, is an important key towards understanding the atmospheric composition and evolution over the lifetime of the solar system. For an unmagnetized planet such as Venus or Mars when the neutral exosphere extends into the flowing solar wind plasma, loss of pick-up ions upstream of …
Behavior of current sheets at directional magnetic discontinuities in the solar wind at 0.72 AU
Russell, C. T.; Zhang, T. L.; Glassmeier, K. -H. +10 more
Venus Express interplanetary magnetic field measurements have been examined for magnetic ``holes,'' accompanied by magnetic field directional changes. We examine both the thickness of the current sheet and the depth of the magnetic field depression. We find the thickness of the current sheet is not correlated with the depth of the field depression…