Progress on measurement of temperature-dependent H2-broadening of CH4 in the near infrared and N2-N2 collision-induced absorption in the far-infrared.
Abstract
We have measured (A) temperature dependence of H2-broadening of CH4 in the near infrared at temperatures between 90 and 370 K, and (B) collision-induced absorption of N2-N2 system in the far-infrared at the temperatures between 78 K and 130 K. (A) In support of the Jovian and exoplanet atmospheric remote sensing in the near infrared, we have measured the temperature dependence of H2-broadened half width and pressure shift coefficients of CH4, both of which are known to be rotational quantum number dependent. We studied both cold and hot CH4 in the K band ( 2.2 μm) with the focus on a) weaker lines in the v2+v3 band at low temperatures for cold giant planets and b) stronger lines in the v3+v4 band at elevated temperatures for extra-solar planets (e.g., hot-Jupiters). Three custom-built gas absorption cells (two cold and one hot) were used to obtain the spectra of CH4 and H2 mixtures at temperatures between 100 and 370 K. We will discuss our on-going spectrum analysis for a few select J manifolds and provide comparisons with published values, which are available only at room temperature. (B) Nitrogen collision-induced absorption provides the primary opacity of Titan at long wavelengths, thereby playing a critical role in determining the heat balance as well as the atmospheric composition and dynamics. Our new measurements of the nitrogen absorption spectrum at temperatures from 78 to 130 K are consistently 20% higher than predictions made using theoretical models of Borysow and Frommhold (1986) and of Karman et al. (2015). However, the new data are consistent with the previous measurements at 78 K by the UBC group (Wishnow et al. 1996). We present preliminary results for the N2-N2 CIA coefficients and their temperature dependence between 78 and 130 K, and comparisons with the above theoretical calculations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.P33B2131S
- Keywords:
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- 5704 Atmospheres;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5706 Aurorae;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5724 Interiors;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5737 Magnetospheres;
- PLANETARY SCIENCES: FLUID PLANETS