Planetary atmosphere observation analysis

Abstract:

Jupiter's Great Red Spot (GRS) was mapped by the James Webb Space Telescope (JWST)/Mid‐Infrared Instrument (4.9–27.9 μ ${\upmu }$ m) in July and August 2022. These observations took place alongside a suite of visual and infrared observations from; Hubble, JWST/NIRCam, Very Large Telescope/VISIR and amateur observers which provided both spatial and temporal context across the jovian disc. The stratospheric temperature structure retrieved using the NEMESIS software revealed a series of hot‐spots above the GRS. These could be the consequence of GRS‐induced wave activity. In the troposphere, the temperature structure was used to derive the thermal wind structure of the GRS vortex. These winds were only consistent with the independently determined wind field by JWST/NIRCam at 240 mbar if the altitude of the Hubble‐derived winds were located around 1,200 mbar, considerably deeper than previously assumed. No enhancement in ammonia was found within the GRS but a link between elevated aerosol and phosphine abundances was observed within this region. North‐south asymmetries were observed in the retrieved temperature, ammonia, phosphine and aerosol structure, consistent with the GRS tilting in the north‐south direction. Finally, a small storm was captured north‐west of the GRS that displayed a considerable excess in retrieved phosphine abundance, suggestive of vigorous convection. Despite this, no ammonia ice was detected in this region. The novelty of JWST required us to develop custom‐made software to resolve challenges in calibration of the data. This involved the derivation of the “FLT‐5” wavelength calibration solution that has subsequently been integrated into the standard calibration pipeline.

Abstract:

The goal of this white paper is to provide a snapshot of the data availability and data needs primarily for the Ariel space mission, but also for related atmospheric studies of exoplanets and cool stars. It covers the following data-related topics: molecular and atomic line lists, line profiles, computed cross-sections and opacities, collision-induced absorption and other continuum data, optical properties of aerosols and surfaces, atmospheric chemistry, UV photodissociation and photoabsorption cross-sections, and standards in the description and format of such data. These data aspects are discussed by addressing the following questions for each topic, based on the experience of the ‘data-provider’ and ‘data-user’ communities: (1) what are the types and sources of currently available data, (2) what work is currently in progress, and (3) what are the current and anticipated data needs. We present a GitHub platform for Ariel-related data, with the goal to provide a go-to place for both data-users and data-providers, for the users to make requests for their data needs and for the data-providers to link to their available data. Our aim throughout the paper is to provide practical information on existing sources of data whether in data bases, theoretical, or literature sources.

Abstract:

A laboratory study was performed using the Visible Oxford Space Environment Goniometer in which the broadband (350–1250 nm) bidirectional reflectance distribution functions (BRDFs) of two representative Apollo regolith samples were measured, for two surface roughness profiles, across a range of viewing angles—reflectance: 0–70°, in steps of 5°; incidence: 15°, 30°, 45°, and 60°; and azimuthal: 0°, 45°, 90°, 135°, and 180°. The BRDF datasets were fitted using the Hapke BRDF model to (1) provide a method of comparison to other photometric studies of the lunar regolith and (2) to produce Hapke parameter values which can be used to extrapolate the BRDF to all angles. Importantly, the surface profiles of the samples were characterized using an Alicona 3D® instrument, allowing two of the free parameters within the Hapke model, φ and θ ¯ $$ \overline{\theta} $$ , which represent porosity and surface roughness, respectively, to be constrained. The study determined that, for θ ¯ $$ \overline{\theta} $$ , the 500–1000 μm size‐scale is the most relevant for the BRDF. Thus, it deduced the following “best fit” Hapke parameters for each of the samples: Apollo 11 rough— w $$ w $$ = 0.315 ± 0.021, b $$ b $$ = 0.261 ± 0.007, and h S $$ {h}_S $$ = 0.039 ± 0.005 (with θ ¯ $$ \overline{\theta} $$ = 21.28° and φ = 0.41 ± 0.02); Apollo 11 smooth— w $$ w $$ = 0.281 ± 0.028, b $$ b $$ = 0.238 ± 0.008, and h S $$ {h}_S $$ = 0.032 ± 0.006 (with θ ¯ $$ \overline{\theta} $$ = 13.80° and φ = 0.60 ± 0.02); Apollo 16 rough— w $$ w $$ = 0.485 ± 0.155, b $$ b $$ = 0.155 ± 0.083, and h S $$ {h}_S $$ = 0.135 ± 0.007 (with θ ¯ $$ \overline{\theta} $$ = 21.69° and φ = 0.55 ± 0.02); Apollo 16 smooth— w $$ w $$ = 0.388 ± 0.057, b $$ b $$ = 0.063 ± 0.033, and h S $$ {h}_S $$ = 0.221 ± 0.011 (with θ ¯ $$ \overline{\theta} $$ = 14.27° and φ = 0.40 ± 0.02). Finally, updated hemispheric albedo functions were determined for the samples, which can be used to set laboratory measured visible scattering functions within thermal models.

Abstract:

The detection of hydrogen chloride (HCl) in the atmosphere of Mars was among the primary objectives of the ExoMars Trace Gas Orbiter (TGO) mission. Its discovery using the Atmospheric Chemistry Suite mid‐infrared channel (ACS MIR) showed a distinct seasonality and possible link to dust activity. This paper is part 2 of a study investigating the link between HCl and aerosols by comparing gas measurements made with TGO to dust and water ice opacities measured with the Mars Climate Sounder (MCS). In part 1, we showed, and compared, the seasonal evolution of vertical profiles of HCl, water vapor, temperature, dust opacity, and water ice opacity over the dusty periods around perihelion (solar longitudes 180°–360°) across Mars years 34–36. In part 2, we investigated the quantitative correlations in the vertical distribution between each quantity, as well as ozone. We show that there is a strong positive correlation between HCl and water vapor, which is expected due to fast photochemical production rates for HCl when reacting with water vapor photolysis products. We also show a strong positive correlation between water vapor and temperature, but are unable to show any correlation between temperature and HCl. There are weak correlations between the opacities of dust and water ice, and dust and water vapor, but only very low correlations between dust and HCl. We close with a discussion of possible sources and sinks and that interactions between HCl and water ice are the most likely for both, given the inter‐comparison.