AR 1585 (Archival Research)

Sun Jun 4 05:07:37 GMT 2023

Principal Investigator: Glenn Orton
PI Institution: Jet Propulsion Laboratory
Investigators (xml)

Title: Analysis of GTO Observations of Uranus by the MIRI Instrument
Cycle: 1

Observations of Uranus by the MIRI instrument made in the GTO program 1248 will be analyzed for spatial variability of temperatures, composition and possible stratospheric hazes. We concentrate this effort on three particular topics. (1) Determine the deep tropospheric structure. Its global mean is a key to understanding the accuracy of a model whose spectrum is now used as a calibration standard for submillimeter and longer wavelengths. This is very important in light of our ongoing analysis on Herschel and ISO observations that imply a protosolar mixture of helium and hydrogen, making Uranus unlike the helium-depleted atmospheres of giant planets Jupiter and Saturn. Testing this model critically involves examining the center-to-limb structure of 9-11 micron radiances to diagnose the presence of a warm, emitting particulate layer in the stratosphere. (2) Determine upper-tropospheric/lower- stratospheric temperatures and spin states of H2, providing an indirect constraint on vertical motions. (3) Determine the temperature structure and H2 spin state of the stratosphere using center-to-limb behavior of H2 quadrupole and dimer lines that will distinguish between alternative models derived from analysis of Spitzer IRS observations. These results will be compared with Voyager-2 IRIS, Spitzer IRS (disk-averaged), and spatially resolved ground-based thermal images and spectra. This comparison will clarify ambiguities in their analysis and measure long-term evolution of atmospheric properties one season after the 1986 spatially resolved Voyager-2 measurements of thermal emission.