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Correlations between cloud thickness and sub‐cloud water abundance on Venus
Author(s) -
Tsang Constantine C. C.,
Wilson Colin F.,
Barstow Joanna K.,
Irwin Patrick G. J.,
Taylor Fredric W.,
McGouldrick Kevin,
Piccioni Giuseppe,
Drossart Pierre,
Svedhem Håkan
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl041770
Subject(s) - venus , water vapor , atmospheric sciences , altitude (triangle) , abundance (ecology) , atmosphere of mars , spatial variability , environmental science , depth sounding , wavelength , atmosphere of venus , cloud top , mars exploration program , remote sensing , geology , astrobiology , physics , martian , meteorology , astronomy , satellite , oceanography , statistics , geometry , mathematics , fishery , biology , optoelectronics
Past spacecraft observations of Venus have found considerable spatial and temporal variations of water vapour abundance above the clouds. Previous searches for variability below the clouds at 30–45 km altitude found no large scale latitudinal gradients, but lacked the spatial resolution to detect smaller scale variations. Here we interpret results from the VIRTIS imaging spectrometer on Venus Express, remotely sounding at near‐infrared ‘spectral window’ wavelengths, as indicating that the water vapour abundance at 30–40 km altitude varies from 22 to 35 ppmv (±4 ppmv). Furthermore, this variability is correlated with cloud opacity, supporting the hypothesis that its genesis is linked to cloud convection. It is also possible to fit the observations without requiring spatial variation of water abundance, but this places a strong constraint on the spectral dependence of the refractive index data assumed for the lower cloud particles, for which there is as yet no supporting evidence.