Mapping zonal winds at Venus’s cloud tops from ground-based Doppler velocimetry

Six years of Venus winds at the upper cloud level from UV, visible and near infrared observations from VIRTIS on Venus Express

“…Reported errors for measurements of a single day can be 20-30 m s À 1 in the best cases and the spatial resolution is in general lower than from cloud tracking using spacecraft data. However the overall agreement between Doppler velocities and results from VEx cross-validates both the cloud tracking and the Doppler velocimetry results as representative of the motions at the upper cloud level (Machado et al, 2012(Machado et al, , 2014.…”

“…The VMC results indicate variability at these latitudes and the emergence and disappearance of the jet in different orbits but always within the velocity error bar (Khatuntsev et al, 2013). High-resolution direct measurements of instantaneous zonal winds from Doppler observations using the VLT provide additional evidence for the occasional presence of modest jets at 501 (Machado et al, 2012). Our temporal resolution is not high enough to resolve the emergence and disappearance of the South mid-latitudes jet.…”

“…These features, loosely correlated with the ultraviolet details, are generally considered to lie about 5-8 km below the ultraviolet cloud top and their motions were first studied from images obtained by the Galileo orbiter on its Venus flyby (Belton et al, 1991;Peralta et al, 2007). Although the cloud motions are a good proxy for true atmospheric motions Machado et al, 2012Machado et al, , 2014 the apparent motion of clouds can be different in regions covered by atmospheric waves which seem ubiquitous in Venus atmosphere Piccialli et al, 2014) and present different scales and physical origins (Peralta et al, 2014a(Peralta et al, , 2014b. Nevertheless, studying the cloud motions is the best-suited technique at present capable to provide a systematic long-term analysis of the atmospheric winds (zonal and meridional) and disentangle the short and long time-scales variations.…”

“…At the cloud top, winds can be obtained from Doppler shifts of solar lines (Widemann et al, 2007Gaulme et al, 2008;Machado et al, 2012). The cloud top altitude is generally defined as the altitude level where the optical depth at a given wavelength is 1.…”

Comparison of general circulation model atmospheric wave simulations with wind observations of venusian mesosphere

“…There have been detections of many atmospheric waves in the cloud layer in the venusian atmosphere (Rossow et al, 1980;Belton et al, 1976;Markiewicz et al, 2007;Peralta et al, 2008;Titov et al, 2012;Machado et al, 2012). Possible trigger for the atmospheric waves in the mesosphere is the convective motion in the two marginally stable regions from 18 to 30 km altitude and 48 to 55 km altitude (Seiff et al, 1980).…”