Details

Autor(en) / Beteiligte

• Garate‐Lopez, I.
• Hueso, R.
• Sánchez‐Lavega, A.
• García Muñoz, A.

Titel

Potential vorticity of the south polar vortex of Venus

Ist Teil von

• Journal of geophysical research. Planets, 2016-04, Vol.121 (4), p.574-593

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Venus' atmosphere shows highly variable warm vortices over both of the planet's poles. The nature of the mechanism behind their formation and properties is still unknown. Potential vorticity is a conserved quantity when advective processes dominate over friction and diabatic heating and is a quantity frequently used to model balanced flows. As a step toward understanding the vortices' dynamics, we present maps of Ertel's potential vorticity (EPV) at Venus' south polar region. We analyze three configurations of the south polar vortex at the upper cloud level (P ~ 240 mbar; z ~ 58 km), based on our previous analyses of cloud motions and thermal structure from data acquired by the Visual and InfraRed Thermal Imaging Spectrometer instrument on board Venus Express. Additionally, we tentatively estimate EPV at the lower cloud level (P ~ 2200 mbar; z ~ 43 km), based on our previous wind measurements and on static stability data from Pioneer Venus and the Venus International Reference Atmosphere (VIRA) model. Values of EPV are on the order of 10−6 and 10−8 K m2 kg−1 s−1 at the upper and lower cloud levels, respectively, being 3 times larger than the estimated errors. The morphology observed in EPV maps is mainly determined by the structures of the vertical component of the relative vorticity. This is in contrast to the vortex's morphology observed in 3.8 or 5 µm images which are related to the thermal structure of the atmosphere at the cloud top. Some of the EPV maps point to a weak ringed structure in the upper cloud, while a more homogenous EPV field is found in the lower cloud. Key Points We present Ertel's potential vorticity (EPV) maps of Venus' south polar vortex The relative vorticity dominates over the thermal term in the EPV calculation EPV is ~2 × 10−6 and ~2 × 10−8 K m2 kg−1 s−1 in the upper and lower clouds, respectively