ﻻ يوجد ملخص باللغة العربية
We present the detection and characterisation of mesoscale waves on the lower clouds of Venus using images from the Visible Infrared Thermal Imaging Spectrometer onboard the European Venus Express space mission and from the 2 $mu$m camera (IR2) instrument onboard the Japanese space mission Akatsuki. We used image navigation and processing techniques based on contrast enhancement and geometrical projections to characterise morphological properties of the detected waves, such as horizontal wavelength and the relative optical thickness drop between crests and troughs. Additionally, we performed phase velocity and trajectory tracking of wave packets. We combined these observations to derive other properties of the waves such as the vertical wavelength of detected packets. Our observations include 13 months of data from August 2007 to October 2008, and the entire available data set of IR2 from January to November 2016.We characterised almost 300 wave packets across more than 5500 images over a broad region of the globe of Venus. Our results show a wide range of properties and are not only consistent with previous observations but also expand upon them, taking advantage of two instruments that target the same cloud layer of Venus across multiple periods. In general, waves observed on the nightside lower cloud are of a larger scale than the gravity waves reported in the upper cloud. This paper is intended to provide a more in-depth view of atmospheric gravity waves on the lower cloud and enable follow-up works on their influence in the general circulation of Venus.
Planetary-scale waves are thought to play a role in powering the yet-unexplained atmospheric superrotation of Venus. Puzzlingly, while Kelvin, Rossby and stationary waves manifest at the upper clouds (65--70 km), no planetary-scale waves or stationar
We present measurements of the wind speeds at the nightside lower clouds of Venus from observations by JAXAs mission Akatsuki during 2016, complemented with new wind measurements from ground-based observations acquired with TNG/NICS in 2012 and IRTF/
One of the striking features about Venus atmosphere is its temporal variability and dynamics, with a chaotic polar vortex, large-scale atmospheric waves, sheared features, and variable winds that depend on local time and possibly orographic features.
We first respond to two points raised by Villanueva et al. We show the JCMT discovery spectrum of PH3 can not be re-attributed to SO2, as the line width is larger than observed for SO2 features, and the required abundance would be an extreme outlier.
We published spectra of phosphine molecules in Venus clouds, following open-science principles in releasing data and scripts (with community input leading to ALMA re-processing, now benefiting multiple projects). Some misconceptions about de-trending