[1] One of the objectives of spectrometers onboard space missions is to retrieve atmospheric parameters (notably density, composition and temperature). To fulfill this objective, comparisons between observations and model results are necessary. Knowledge of these model uncertainties is therefore necessary, although usually not considered, to estimate the accuracy in planetary upper atmosphere remote sensing of these parameters. In Part I of this study, "Computing uncertainties in ionosphere-airglow models: I. Electron flux and species production uncertainties for Mars" (Gronoff et al., 2012), we presented the uncertainties in the production of excited states and ionized species from photon and electron impacts, computed with a Monte-Carlo approach, and we applied this technique to the Martian upper atmosphere. In the present paper, we present the results of propagation of these production errors to the main UV emissions and the study of other sources of uncertainties. As an example, we studied several aspects of the model uncertainties in the thermosphere of Mars, and especially the O( 1 S) green line (557.7 nm, with its equivalent, the trans-auroral line at 297.2 nm), the Cameron bands CO(a 3 P), and CO 2 + (B 2 S u + ) doublet emissions. We first show that the excited species at the origin of these emissions are mainly produced by electron and photon impact. We demonstrate that it is possible to reduce the computation time by decoupling the different sources of uncertainties; moreover, we show that emission uncertainties can be large (>30%) because of the strong sensitivity to the production uncertainties. Our study demonstrates that uncertainty calculations are a crucial step prior to performing remote sensing in the atmosphere of Mars and the other planets and can be used as a guide to subsequent adjustments of cross sections based on aeronomical observations. Finally, we compare the simulations with observations from the SPICAM spectrometer on the Mars Express spacecraft. The production of excited species at the origin of the green line, the CO Cameron bands and the CO 2 + (B) doublet is found to be on the dayside, consistent with photon and electron impact on CO 2 as the main source of excitation of the three emissions, in contrast to the findings of Huestis et al. (2010) for the O( 1 S) case. Moreover, we re-examine the cross section for the production of the Cameron bands by electron impact on CO 2 .

Context. Modelling of the Venusian ionosphere fluorescence is required, to analyse data being collected by the SPICAV instrument onboard Venus Express. Aims. We present the modelling of the production of excited states of O, CO and N 2 , which enables the computation of nightglow emissions. In the dayside, we compute several emissions, taking advantage of the small influence of resonant scattering for forbidden transitions. Methods. We compute photoionisation and photodissociation mechanisms, and the photoelectron production. We compute electron impact excitation and ionisation, through a multi-stream stationary kinetic transport code. Finally, we compute the ion recombination using a stationary chemical model. Results. We predict altitude density profiles for O( 1 S) and O( 1 D) states, and emissions corresponding to their different transitions. They are found to agree with observations. In the nightside, we discuss the different O( 1 S) excitation mechanisms as a source of green line emission. We calculate production intensities of the O( 3 S) and O( 5 S) states. For CO, we compute the Cameron bands and the Fourth Positive bands emissions. For N 2 , we compute the LBH, first and Second Positive bands. All values are compared successfully to experiments when data are available. Conclusions. For the first time, a comprehensive model is proposed to compute dayglow and nightglow emissions of the Venusian upper atmosphere. It relies on previous works with noticeable improvements, both on the transport side and on the chemical side. In the near future, a radiative-transfer model will be used to compute optically-thick lines in the dayglow, and a fluid model will be added to compute ion densities.

[1] This study is based on multi-planet multi-wavelength observations of planetary aurorae throughout the heliosphere, acquired along the propagation path of a series of consecutive interplanetary shocks. The underlying motivation to track the shocks was to increase the probability of detection of auroral emissions at Uranus. Despite several Earth-based attempts in the past few years, at Far-UV (FUV) and Near-IR (NIR) wavelengths, such emissions have never been unambiguously reobserved since their discovery by Voyager 2 in 1986. Here, we present a campaign of FUV observations of Uranus obtained in November 2011 with the Hubble Space Telescope (HST) during active solar wind conditions. We positively identify auroral signatures in several of these HST measurements, together with some obtained in 1998, representing the first images of Uranus' aurorae. We analyze their characteristics and discuss the implications for the asymmetric Uranian magnetosphere and its highly variable interaction with the solar wind flow from near-solstice (1986) to near-equinox (2011) configurations.

Abstract. The mean energy W expended in a collision of electrons with atmospheric gases is a useful parameter for fast aeronomy computations. Computing this parameter in transport kinetic models with experimental values can tell us more about the number of processes that have to be taken into account and the uncertainties of the models. We present here computations for several atmospheric gases of planetological interest (CO 2 , CO, N 2 , O 2 , O, CH 4 , H, He) using a family of multi-stream kinetic transport codes. Results for complete atmospheres for Venus, Earth, Mars, Jupiter and Titan are also shown for the first time. A simple method is derived to calculate W of gas mixtures from single-component gases and is conclusively checked against the W values of these planetary atmospheres. Discrepancies between experimental and theoretical values show where improvements can be made in the measurement of excitation and dissociation cross-sections of specific neutral species, such as CO 2 and CO.