P056-0005
SOFIA FORCAST observations of Jupiter in the JWST-era

Monday, 14 December 2020
Poster
Imke De Pater, Univ California Berkeley, Berkeley, CA, United States, William T Reach, USRA, Moffett Field, CA, United States, Leigh N. Fletcher, University of Leicester, Leicester, United Kingdom, Charles Goullaud, University of California Berkeley, Berkeley, CA, United States and Michael H. Wong, University of California, Berkeley, CA, United States
Abstract:
Jupiter, the most accessible example for the study of atmospheric circulation on a giant planet, serves as a template for our understanding of the atmospheric dynamics and chemistry of the ever-growing number of extrasolar planets. The atmospheres of giant planets are extremely active, varying on timescales ranging from decades (seasonally evolving chemistry and clouds), to months (variability of storms and banded structures) and even minutes (e.g., asteroidal/cometary impacts and localized storm systems). These evolving atmospheres serve as natural planetary-scale laboratories for studying the fundamental meteorology, chemistry and evolutionary mechanisms that shape the worlds around us. SOFIA’s remote sensing in the far-IR penetrates thick upper-tropospheric hazes to explore the complex, turbulent dynamics of Jupiter's weather layer.

In 2014 we observed Jupiter with FORCAST at 17-37 micron to constrain the shape of its continuum emission (Fletcher et al., 2017, Ic. 286, 223), which can only be achieved if obscuration by telluric water vapor is minimized, i.e., from SOFIA or from space. The SOFIA data confirmed the Voyager findings in detecting an equator to pole increase in the para-H2 fraction (fp), with low fp and sub-equilibrium conditions at the equator and high fp and super-equilibrium conditions polewards of 60° latitude. The para-H2 fraction traces mean vertical mixing on timescales of years to decades, depending on the poorly-known hydrogen equilibration time in Jupiter's atmosphere. Equilibrium fp thus implies weak vertical mixing, while sub- or super-equilibrium fractions correspond to mean upwelling or subsidence, respectively (in the upper troposphere where fp is measured). Interestingly, both Voyager and SOFIA measured higher fp values at high northern latitudes than at high southern latitudes, suggesting an asymmetry between the two hemispheres where none is expected on the basis of seasonal variability. We discuss the advantages of a similar experiment simultaneously with JWST/ERS observations planned to be carried out after launch.

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