Planetary atmosphere observation analysis

Abstract:

The loss of water from Mars to space is thought to result from the transport of water to the upper atmosphere, where it is dissociated to hydrogen and escapes the planet. Recent observations have suggested large, rapid seasonal intrusions of water into the upper atmosphere, boosting the hydrogen abundance. We use the Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter to characterize the water distribution by altitude. Water profiles during the 2018–2019 southern spring and summer stormy seasons show that high-altitude water is preferentially supplied close to perihelion, and supersaturation occurs even when clouds are present. This implies that the potential for water to escape from Mars is higher than previously thought.

Abstract:

Venus is home to thousands of volcanoes, with a wide range of volumes and sizes. Its surface is relatively young, with a temperature of approximately 735 K and an atmosphere of 92 bar. Past and possible ongoing volcanic outgassing is expected to provide a source to the sustenance of this massive atmosphere, dominated by CO2 and SO2. The lower atmosphere can be investigated in the near-infrared transparency windows on the nightside, such as the 2.3μm thermal emission window, which provides a chance of detection of species with volcanic origin, such as water vapor. The Planetary Spectrum Generator was used to simulate the nightside 2.3μm thermal emission window of Venus. We simulated the effect of a volcanic gas plume rising to a ceiling altitude, for species such as H2O, CO, OCS, HF and SO2. The sensitivity of the radiance spectrum at different wavelengths was explored as an attempt to qualitatively access detection for future measurements of both ground-based and space-instrumentation. We conclude from our qualitative analysis that for the H2O, CO and OCS plumes simulated there is potential to achieve a detection in the future, given a minimum required signal-to-noise ratio of 50. For SO2 and HF plumes, a higher signal-to-noise ratio would be needed.

Abstract:

<jats:title>Abstract</jats:title> <jats:p>Using a newly developed ‘holistic’ atmospheric model of the aerosol structure in Uranus’s atmosphere, based upon observations made by HST/STIS, Gemini/NIFS and IRTF/SpeX from 2000 – 2009, we make a new estimate the bolometric Bond albedo of Uranus during this time of A* = 0.338 ± 0.011, with a phase integral of q* = 1.36 ± 0.03. Then, using a simple seasonal model, developed to be consistent with the disc-integrated blue and green magnitude data from the Lowell Observatory from 1950 – 2016, we model how Uranus’s reflectivity and heat budget vary during its orbit and determine new orbital-mean average values for the bolometric Bond albedo of $\overline{A^*} = 0.349 \pm 0.016$ and for the absorbed solar flux of $\overline{P_\mathrm{in}}=0.604 \pm 0.027$ W m−2. Assuming the outgoing thermal flux to be $\overline{P_\mathrm{out}}=0.693 \pm 0.013$ W m−2, as previously determined from Voyager 2 observations, we arrive at a new estimate of Uranus’s average heat flux budget of Pout/Pin = 1.15 ± 0.06, finding considerable variation with time due to Uranus’s significant orbital eccentricity of 0.046. This leads the flux budget to vary from Pout/Pin = 1.03 near perihelion, to 1.24 near aphelion. We conclude that although Pout/Pin is considerably smaller than for the other giant planets, Uranus is not in thermal equilibrium with the Sun.</jats:p>