Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR on board Venus Express: Carbon dioxide measurements at the Venus terminator

[1] SOIR is a high-resolution spectrometer flying on board the ESA Venus Express mission. It performs solar occultations of the Venus high atmosphere, and so defines unique vertical profiles of many of the Venus key species. In this paper, we focus on the Venus main constituent, carbon dioxide. We explain how the temperature, the total density, and the total pressure are derived from the observed CO2 density vertical profiles. A striking permanent temperature minimum at 125 km is observed. The data set is processed in order to obtain a Venus Atmosphere from SOIR measurements at the Terminator (VAST) compilation for different latitude regions and extending from 70 up to 170 km in altitude. The results are compared to many literature results obtained from ground-based observations, previous missions, and the Venus Express mission. The homopause altitude is also determined.

[1]  R. Dickinson,et al.  Models of Venus neutral upper atmosphere: Structure and composition , 1985 .

[2]  Eric Villard,et al.  HDO and H2O vertical distributions and isotopic ratio in the Venus mesosphere by Solar Occultation at Infrared spectrometer on board Venus Express , 2008 .

[3]  M. Jacobson.  Fundamentals of Atmospheric Modeling: Contents , 1998 .

[4]  G. Keating,et al.  Venus upper atmosphere structure , 1980 .

[5]  C. Rodgers.  Characterization and Error Analysis of Profiles Retrieved From Remote Sounding Measurements , 1990 .

[6]  R. Clancy,et al.  Thermal structure and CO distribution for the Venus mesosphere/lower thermosphere: 2001–2009 inferior conjunction sub-millimeter CO absorption line observations , 2012 .

[7]  Xi Zhang,et al.  Vertical profiling of SO 2 and SO above Venus' clouds by SPICAV/SOIR solar occultations , 2012 .

[8]  C. B. Farmer,et al.  Structure and meteorology of the middle atmosphere of Venus: Infrared remote sensing from the Pioneer Orbiter , 1980 .

[9]  J. Gérard,et al.  Atomic oxygen distributions in the Venus thermosphere: Comparisons between Venus Express observations and global model simulations , 2012 .

[10]  J. P. Dubois,et al.  SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere , 2007 .

[11]  R. Dickinson,et al.  Venus mesosphere and thermosphere: II. Global circulation, temperature, and density variations , 1986 .

[12]  S. C. Sommer,et al.  Measurements of thermal structure and thermal contrasts in the atmosphere of Venus and related dynamical observations: Results From the four Pioneer Venus Probes , 1980 .

[13]  V. Moroz,et al.  Structure of the Venusian atmosphere from surface up to 100 km , 2006 .

[14]  Gang Li,et al.  The HITRAN 2008 molecular spectroscopic database , 2005 .

[15]  A. Vandaele,et al.  Composition of the Venus mesosphere measured by Solar Occultation at Infrared on board Venus Express , 2008 .

[16]  Giuseppe Piccioni,et al.  Spatial variability of carbon monoxide in Venus' mesosphere from Venus Express/Visible and Infrared Thermal Imaging Spectrometer measurements , 2008 .

[17]  A. Vandaele,et al.  First observations of SO2 above Venus' clouds by means of Solar Occultation in the Infrared , 2008 .

[18]  P. Drossart,et al.  Investigation of air temperature on the nightside of Venus derived from VIRTIS-H on board Venus-Express , 2012 .

[19]  Eric Villard,et al.  Compact high-resolution spaceborne echelle grating spectrometer with acousto-optical tunable filter based order sorting for the infrared domain from 2.2 to 4.3 microm. , 2006, Applied optics.

[20]  E. Lellouch,et al.  Global circulation, thermal structure, and carbon monoxide distribution in Venus' mesosphere in 1991 , 1994 .

[21]  R. Clancy,et al.  Observational definition of the Venus mesopause: vertical structure, diurnal variation, and temporal instability , 2003 .

[22]  D. Hunten,et al.  The upper atmosphere of Venus during morning conditions , 1980 .

[23]  Mark Z. Jacobson,et al.  Fundamentals of atmospheric modeling , 1998 .

[24]  B. Bézard,et al.  The 12C/13C and 16O/18O ratios in the atmosphere of Venus from high-resolution 10-μm spectroscopy , 1987 .

[25]  Martin Pätzold,et al.  Dynamical properties of the Venus mesosphere from the radio-occultation experiment VeRa onboard Venus Express , 2012 .

[26]  Giuseppe Piccioni,et al.  Near-IR oxygen nightglow observed by VIRTIS in the Venus upper atmosphere , 2009 .

[27]  J. P. Dubois,et al.  A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H2O and HDO , 2007, Nature.

[28]  Wayne T. Kasprzak,et al.  Global empirical model of the Venus thermosphere , 1983 .

[29]  R. Clancy,et al.  Venus upper atmospheric CO, temperature, and winds across the afternoon/evening terminator from June 2007 JCMT sub-millimeter line observations , 2008 .

[30]  R. Dickinson,et al.  Venus mesosphere and thermosphere. III - Three-dimensional general circulation with coupled dynamics and composition , 1988 .

[31]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[32]  T. Hewagama,et al.  Thermospheric/mesospheric temperatures on Venus: Results from ground-based high-resolution spectroscopy of CO 2 in 1990/1991 and comparison to results from 2009 and between other techniques , 2012 .

[33]  U. Zahn,et al.  Venus: eddy coefficients in the thermosphere and the inferred helium content of the lower atmosphere , 1979 .

[34]  M. Pätzold,et al.  Structure of the Venus neutral atmosphere as observed by the Radio Science experiment VeRa on Venus Express , 2009 .

[35]  A. Vandaele,et al.  A new method for determining the transfer function of an acousto optical tunable filter. , 2009, Optics express.

[36]  J. Fox,et al.  Near-terminator Venus ionosphere: Evidence for a dawn/dusk asymmetry in the thermosphere , 2007 .

[37]  V. M. Linkin,et al.  Structure of the Venus atmosphere , 2007 .

[38]  A. Brecht.  Tracing the Dynamics in Venus' Upper Atmosphere. , 2011 .

[39]  A. Vandaele,et al.  Composition of the Venus mesosphere measured by SOIR on board Venus Express , 2008 .

[40]  Duane O. Muhleman,et al.  Long-term (1979–1990) changes in the thermal, dynamical, and compositional structure of the Venus Mesosphere as inferred from microwave spectral line observations of 12CO, 13CO, and C18O , 1991 .

[41]  Eric Villard,et al.  In-flight performance and calibration of SPICAV SOIR onboard Venus Express. , 2008, Applied optics.

[42]  A. Vandaele,et al.  Optical extinction due to aerosols in the upper haze of Venus: Four years of SOIR/VEX observations from 2006 to 2010 , 2012 .

[43]  Eddy Neefs,et al.  Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR on board Venus Express: Retrieval technique , 2010 .