Issue |
A&A
Volume 484, Number 2, June III 2008
|
|
---|---|---|
Page(s) | 547 - 553 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361:20079288 | |
Published online | 26 March 2008 |
A study of the Martian water vapor over Hellas using OMEGA and PFS aboard Mars Express
1
LESIA, Observatoire de Paris, CNRS, UPMC, Univ. Denis Diderot, 92195 Meudon, France e-mail: therese.encrenaz@obspm.fr
2
Institut d'Astrophysique Spatiale, Orsay Campus, 91405 Orsay, France
3
IPSL/LMD, place Jussieu, 75231 Paris Cedex 05, France
4
MPS, Max-Planck St. 2, 37191 Katlenburg-Lindau, Germany
5
INAF-IFSI, Via del Fosso del Cavaliere 100, 00133 Rome, Italy
Received:
20
December
2007
Accepted:
22
February
2008
We used the OMEGA imaging spectrometer aboard Mars Express
to
study the evolution of the water vapor abundance over the Hellas basin, as
a function of the seasonal cycle. The H2O column density is found
to range from very low values (between southern fall
and winter) up to more than 15 pr-μm during southern spring and summer.
The general behavior is consistent with the expected seasonal cycle
of water vapor on Mars, as previously observed by TES and
modeled. In particular, the maximum water vapor
content is observed around the southern solstice, and is significantly
less than its northern couterpart. However, there is a noticeable
discrepancy around the northern spring equinox (–60°), where
the observed H2O column densities are significantly lower than the values
predicted by the GCM. Our data show an abrupt enhancement of the
water vapor column density (from 3 to 16 pr-μm)
on a timescale of 3 days, for
–254°. Such an increase,
not predicted by the GCM, was
also occasionally observed by TES over Hellas during previous martian years
at the same season; however, its origin remains to be
understood.
Key words: planets and satellites: individual: Mars / infrared: solar system
© ESO, 2008
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