Analysis of gaseous ammonia (NH3) absorption in the visible spectrum of Jupiter - Update
Icarus Elsevier 321 (2018) 572-582
Abstract:
An analysis of currently available ammonia (NH3) visible-to-near-infrared gas absorption data was recently undertaken by Irwin et al. (2018) to help interpret Very Large Telescope (VLT) MUSE observations of Jupiter from 0.48–0.93 µm, made in support of the NASA/Juno mission. Since this analysis a newly revised set of ammonia line data, covering the previously poorly constrained range 0.5–0.833 µm, has been released by the ExoMol project, “C2018” (Coles et al., 2018), which demonstrates significant advantages over previously available data sets, and provides for the first time complete line data for the previously poorly constrained 5520- and 6475-Å bands of NH3. In this paper we compare spectra calculated using the ExoMol–C2018 data set (Coles et al., 2018) with spectra calculated from previous sources to demonstrate its advantages. We conclude that at the present time the ExoMol–C2018 dataset provides the most reliable ammonia absorption source for analysing low- to medium-resolution spectra of Jupiter in the visible/near-IR spectral range, but note that the data are less able to model high-resolution spectra owing to small, but significant inaccuracies in the line wavenumber estimates. This work is of significance not only for solar system planetary physics, but for future proposed observations of Jupiter-like planets orbiting other stars, such as with NASA’s planned Wide-Field Infrared Survey Telescope (WFIRST).Forward modelling low-spectral-resolution Cassini/CIRS observations of Titan
Experimental Astronomy Springer Nature 57:2 (2024) 15-15
Abstract:
The Composite InfraRed Spectrometer (CIRS) instrument onboard the Cassini spacecraft performed 8.4 million spectral observations of Titan at resolutions between 0.5–15.5 cm-1. More than 3 million of these were acquired at a low spectral resolution (SR) (13.5–15.5 cm-1), which have excellent spatial and temporal coverage in addition to the highest spatial resolution and lowest noise per spectrum of any of the CIRS observations. Despite this, the CIRS low-SR dataset is currently underused for atmospheric composition analysis, as spectral features are often blended and subtle compared to those in higher SR observations. The vast size of the dataset also poses a challenge as an efficient forward model is required to fully exploit these observations. Here, we show that the CIRS FP3/4 nadir low-SR observations of Titan can be accurately forward modelled using a computationally efficient correlated-k method. We quantify wavenumber-dependent forward modelling errors, with mean 0.723 nW cm-2sr-1/cm-1 (FP3: 600–890 cm-1) and 0.248 nW cm-2sr-1/ cm-1 (FP4: 1240–1360 cm-1), that can be used to improve the rigour of future retrievals. Alternatively, in cases where more accuracy is required, we show observations can be forward modelled using an optimised line-by-line method, significantly reducing computation time.Aerosol layers, clouds, spots and the colours of Uranus and Neptune
Copernicus Publications (2024)
Reanalyzing Jupiter ISO/SWS Data through a More Recent Atmospheric Model
(2024)
Abstract:
Improved Design of an Advanced Ice Giants Net Flux Radiometer
Space Science Reviews 220:1 (2024)