Martian thermospheric temperatures retrieved from CO2 + SPICAM dayglow measurements

Conference (2012, December)

A large dataset of dayside grazing limb CO2+ observations performed by the SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) instrument on board Mars Express is analyzed ... [more ▼]

A large dataset of dayside grazing limb CO2+ observations performed by the SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) instrument on board Mars Express is analyzed to retrieve Martian thermospheric temperature, as well as its variation with solar activity, season and latitude. The method permits to retrieve the temperature from the scale height of the CO2+ emission. We also present puzzling features such as limb profiles exhibiting multiple peaks and their characteristics. We furthermore study the behavior of the main emission peak of the CO2+ vertical emission profiles. The CO2+ emission at 289 nm arises from the relaxation of the CO2+* molecule in the B2Σ+ state to the X2Π state. CO2+* molecules are mainly produced in the Martian dayside through photoionisation and photoelectron impact. The CO2+ emission exhibits features that constrain the temperature and density vertical profiles of CO2. Comparisons of retrieved temperatures are made with corresponding simulations from the coupled MGCM-MTGCM. We also use a Monte-Carlo code to model the observed intensity limb profiles. [less ▲]

The vertical distribution of the Venus NO nightglow: limb profiles inversion and one-dimensional modeling

in Icarus (2012), 220

Ultraviolet (UV) spectra of the δ (190-240 nm) and γ (225-270 nm) bands of the nitric oxide (NO) molecule have been measured on the nightside of the atmosphere of Venus with the Spectroscopy for ... [more ▼]

Ultraviolet (UV) spectra of the δ (190-240 nm) and γ (225-270 nm) bands of the nitric oxide (NO) molecule have been measured on the nightside of the atmosphere of Venus with the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) instrument on board Venus Express (VEX). Excited NO molecules on the nightside of the planet are created by radiative recombination of O(3P) and N(4S) atoms. The atoms are produced by photodissociation of CO2 and N2 molecules on the dayside and then transported on the nightside by the global circulation. We analyze all nightside limb profiles obtained since 2006 and provide a statistical study of the nitric oxide airglow layer and its variability. We also apply a spatial deconvolution and an Abel inversion method to the limb profiles to retrieve and quantify the volume emission rate distribution and its dependence on several factors. We also show that about 10% of the limb profiles exhibits a secondary peak located above or below the main airglow peak. Furthermore, a one-dimensional chemical-diffusive model is used to simultaneously model the globally averaged NO and O2(a1Δg) airglow vertical distributions using CO2 and O density profiles rooted in VIRTIS and SPICAV observations. We find that a downward flux of 2×10 9 N(4S) atoms cm−2s−1 and a eddy diffusion coefficient equal to 1 x10 11/sqrt(n) cm−2s−1, where n is the total number density, provide the best set of values to parametrize the one-dimensional representation of the complex 3-D dynamical processes. [less ▲]

The Venus nitric oxide nightglow vertical distribution : update, new features and modelling

Poster (2012, April)

Ultraviolet (UV) spectra of the delta (190-240 nm) and gamma (225-270 nm) bands of the nitric oxide (NO) molecule have been measured in the atmosphere of the Venus night side with the Spectroscopy for ... [more ▼]

Ultraviolet (UV) spectra of the delta (190-240 nm) and gamma (225-270 nm) bands of the nitric oxide (NO) molecule have been measured in the atmosphere of the Venus night side with the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) instrument on board Venus Express (VEX). Excited NO molecules on the night side of the planet find their source in the radiative recombinaison of O(3P) and N(4S) atoms produced on the dayside by Extreme Ultraviolet (EUV) solar photons that cause photodissociation of CO2 and N2 molecules. We analyse with an improved statistics the behaviour of the vertical emission profile of the NO nightglow. We also present a method used to retrieve and analyse the volume emission rate. We describe the dependence of the vertical distribution with latitude and local time and its variability. New features in the vertical distribution of the NO emission such as double peaks are also exhibited. Furthermore, we use a one-dimensional chemical-diffusive model to compare the major features of the calculated O2 1.27 microm and NO UV emissions profiles with those observed with SPICAV. [less ▲]

The Mars and Venus airglow : observations and excitation processes,

Conference (2011, April)

Les émissions aurorales nocturnes de Jupiter

Master's dissertation (2010)

Ce travail de fi n d'études est proposé dans le cadre de la deuxième année de Master en Sciences Spatiales du Département d'Astrophysique, Géophysique et Océanographie de l'Université de Liège. Dans un ... [more ▼]

Ce travail de fi n d'études est proposé dans le cadre de la deuxième année de Master en Sciences Spatiales du Département d'Astrophysique, Géophysique et Océanographie de l'Université de Liège. Dans un premier temps, des rappels concernant la planète Jupiter et le phénomène des aurores polaires qui y ont lieu seront effectués. Le but de ce travail est une première analyse d'un ensemble d'images provenant de l'instrument LORRI à bord de la sonde New Horizons de la NASA. Ces deux outils seront dès lors brièvement présentés. La partie suivante sera consacrée au traitement des images reçues de New Horizons et à leur analyse. En n, nous tirerons des conclusions sur le travail exploratoire réalisé et la pertinence de la base de données. [less ▲]

Les Emissions Aurorales Nocturnes de Jupiter

Book published by Editions Universitaires Europeennes (2010)