Hemispherical distribution of CO above the Venus’ clouds by ground-based 2.3μm spectroscopy

Wave signature in the Venus dayside cloud layer at 58–64 km observed by ground-based infrared spectroscopy

“…4 shows zonal averages of latitudinal variation of the cloud height deviation for three observation sessions. All of them show lower cloud height at higher latitudes than 50°as reported by Ignatiev et al (2009) based on Venus Express/VIRTIS nightside infrared measurements, and by Iwagami et al (2008Iwagami et al ( , 2010 based on ground-based dayside infrared measurements. It is also noticed that the clouds are lower in 2010 than in 2007.…”

“…Since the absorption equivalent width is related to the CO 2 column density within and above the clouds, it may be converted to height deviation of the actual cloud from a reference cloud model. The height deviation is estimated by adjusting cloud height so as to obtain the same equivalent widths for the measured and calculated CO 2 P24 lines in the similar way as Iwagami et al (2008Iwagami et al ( , 2010, and examples are shown in Fig. 2b.…”

Search for horizontal and vertical variations of CO in the day and night side lower mesosphere of Venus from CSHELL/IRTF 4.53μm observations

“…This high-latitude enrichment was also seen by Krasnopolsky (2010) and suspected by Irwin and deKok (2008), although not evidenced by Iwagami et al (2010). A possible interpretation is of dynamical nature: the hemispheric Hadley-cell circulation should result in downdrafts at higher latitudes, where CO produced by photolysis at higher altitudes could be partially brought to the observed altitude range.…”

“…Yet previous measurements of CO on the night side (Irwin and deKok, 2008) and day side (Iwagami et al, 2010;Krasnopolsky, 2010) did not evidence a strong spatial or temporal variability. The mean mixing ratio at cloud top ranges from 30 up to 75 ppmv at cloud top level (with a pressure range between 10 and 100 mbar).…”

Initial products of Akatsuki 1-μm camera

“…The 1.7-and 2.3-μm windows have mainly been used for quantification of gas abundances such as CO, H 2 O and HCl (e.g., Bezard and de Bergh 2007;Tsang et al 2008;Iwagami et al 2008Iwagami et al , 2010Marcq et al 2008;Barstow et al 2012;Arney et al 2014) below the cloud (not exactly at the surface). They found an average H 2 O abundance of 25-35 ppmv with nearly uniform hemispherical distribution.…”