 |
| Titel |
A 1-D radiative conductive model to study the SOIR/VEx thermal profiles |
| VerfasserIn |
Arnaud Mahieux, Justin T. Erwin, Sarah Chamberlain, Séverine Robert, Ann Carine Vandaele, Valerie Wilquet, Ian Thomas, Roger V. Yelle, Jean-Loup Bertaux |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109149
|
| Publikation (Nr.) |
 EGU/EGU2015-9030.pdf |
|
|
|
|
|
| Zusammenfassung |
| SOIR is an infrared spectrometer on board Venus Express that probes the Venus terminator
region since 2006. The measurements are taken on the morning and evening sides of the
terminator, covering all latitudes from the North Pole to the South Pole. Its wavelength range
- 2.2 to 4.3 μm - allows a detailed chemical inventory of the Venus atmosphere [1-5], such as
CO2, CO, H2O, HCl, HF, SO2 and aerosols. CO2 is detected from 70 km up to 165 km, CO
from 70 km to 140 km, and the minor species typically below 110 km down to 70 km.
Number density profiles of these species are computed from the measured spectra.
Temperature profiles are obtained while computing the spectral inversion of the CO2 spectra
combined with the hydrostatic law [6]. These temperature measurements show a striking
permanent temperature minimum (at 125 km) and a weaker temperature maximum (over
100-115 km). The time variability of the CO2 density profiles spans over two orders of
magnitude, and a clear trend is seen with latitude. The temperature variations are also
important, of the order of 35ÂK for a given pressure level, but the latitude variation are
small.
Miss-RT, a 1D radiative transfer model has been developed to reproduce the SOIR
terminator profiles, derived from the Mars thermosphere code presented in [7].
This model has been expanded to better account for the CO2, CO, and O non-LTE
radiative heating and cooling processes which have to be considered in the dense
atmosphere of Venus. Radiative cooling by minor species detected by SOIR (e.g. HCl,
SO2, and H2O) are found to be small in comparison to the 15 μm CO2 cooling.
Aerosol cooling in the 60-90km altitude range may be important to the thermal
balance. There is a good agreement between the 1D model temperature profile
and the mean SOIR temperature profile. Further we can suggest parameters that
can be adjusted to improve the agreement between the model and measurements.
The remaining differences can be attributed to the atmosphere dynamics at the
terminator.
1. Bertaux, J.L., et al., A warm layer in Venus’ cryosphere and high altitude
measurements of HF, HCl, H2O and HDO. Nature, 2007. 450(29 November): p. 646-649,
doi:10.1038/nature05974.
2. Vandaele, A.C., et al., Carbon monoxide short term variability observed on Venus with
SOIR/VEX. Planet. Space Sci., 2014. (in press).
3. Mahieux, A., et al., Venus mesospheric sulfur dioxide measurement retrieved from
SOIR on board Venus Express. Planet. Space Sci., 2014. (in press).
4. Mahieux, A., et al., Hydrogen Halides measurements in the Venus upper
atmosphere retrieved from SOIR on board Venus Express. Planet. Space Sci., 2014. (in
press).
5. Wilquet, V., et al., Optical extinction due to aerosols in the upper haze of Venus:
Four years of SOIR/VEX observations from 2006 to 2010. Icarus, 2012. 217(2): p.
875-881.
6. Mahieux, A., et al., Update of the Venus density and temperature profiles at
high altitude measured by SOIR on board Venus Express. Planet. Space Sci., 2014.
(submitted).
7. Yelle, R., et al., Perturbation of the Mars Atmosphere by the Near-Collision with Comet
C/2013 A1 (Siding Spring). Icarus, 2014. 237: p. 202-210. |
|
|
|
|
|
|