New Observations and Modeling of Jupiter's Quasi-Quadrennial Oscillation

The quasi-quadrennial oscillation (QQO) and its ∼4 year period in Jupiter's atmosphere were first discovered in 7.8 μm infrared observations spanning the 1980s and 1990s from detecting semiregular variations in equatorial brightness temperatures near 10 hPa. New observations that probe between 0.1 and 30 hPa in Jupiter's atmosphere using the Texas Echelon Cross Echelle Spectrograph (TEXES), mounted on the NASA Infrared Telescope Facility, have characterized the vertical structure of the QQO during a complete cycle between January 2012 and April 2016. These new observations show the thermal oscillation previously detected at 10 hPa and that it extends over a pressure range of 2-17 hPa. We have incorporated a spectrum of wave drag parameterizations into the Explicit Planetary Isentropic Code general circulation model to simulate the observed Jovian QQO temperature signatures inferred from the TEXES observations as a function of latitude. A new stochastic wave drag parameterization explores vertical wind structure and offers insight into the spectra of waves that likely exist in Jupiter's atmosphere to force the QQO. High-frequency gravity waves produced from convection likely contribute significantly to the QQO momentum budget. The model temperature outputs show strong correlations to equatorial and surrounding latitude temperature fields retrieved from the TEXES data sets at different epochs. Our results reproduce the QQO phenomenon as a zonal jet that descends over time in response to Jovian atmospheric forcing (e.g., gravity waves from convection)

The Effects of Waves on the Meridional Thermal Structure of Jupiter’s Stratosphere

The American Astronomical Society, find out more The Institute of Physics, find out moreTHE FOLLOWING ARTICLE ISOPEN ACCESSThe Effects of Waves on the Meridional Thermal Structure of Jupiter's StratosphereRichard G. Cosentino1, Thomas Greathouse2, Amy Simon3, Rohini Giles2, Raúl Morales-Juberías4, Leigh N. Fletcher5 and Glenn Orton6Published 2020 November 10 • © 2020. The Author(s). Published by the American Astronomical Society.The Planetary Science Journal, Volume 1, Number 3DownloadArticle PDF DownloadArticle ePubFiguresTablesReferencesDownload PDFDownload ePub318 Total downloadsTurn on MathJaxShare this articleShare this content via emailShare on FacebookShare on TwitterShare on Google+Share on MendeleyHide article informationAuthor affiliations1 Department of Astronomy, University of Maryland, College Park, MD 20742, USA2 Southwest Research Institute, San Antonio, TX 78238, USA3 Solar System Exploration Div., NASA/GSFC, Greenbelt, MD 20771, USA4 Physics Department, New Mexico Institute of Technology, Socorro, NM 87801, USA5 School of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK6 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USAORCID iDsRichard G. Cosentino https://orcid.org/0000-0003-3047-615XThomas Greathouse https://orcid.org/0000-0001-6613-5731Amy Simon https://orcid.org/0000-0003-4641-6186Rohini Giles https://orcid.org/0000-0002-7665-6562Leigh N. Fletcher https://orcid.org/0000-0001-5834-9588Glenn Orton https://orcid.org/0000-0001-7871-2823DatesReceived 2020 June 16Accepted 2020 September 30Published 2020 November 10Check for updates using CrossmarkCitationRichard G. Cosentino et al 2020 Planet. Sci. J. 1 63Create citation alertDOIhttps://doi.org/10.3847/PSJ/abbda3KeywordsJupiter ; Stratosphere ; Infrared observatories Journal RSS feed Sign up for new issue notificationsAbstractA thermal oscillation in Jupiter's equatorial stratosphere, thought to have ~4 Earth year period, was first discovered in 7.8 μm imaging observations from the 1980s and 1990s. Such imaging observations were sensitive to the 10–20 hPa pressure region in the atmosphere. More recent 7.8 μm long-slit high-spectroscopic observations from 2012 to 2017 taken using the Texas Echelon cross-dispersed Echelle Spectrograph (TEXES), mounted on the NASA Infrared Telescope Facility (IRTF), have vertically resolved this phenomenon's structure, and show that it spans a range of pressure from 2 to 20 hPa. The TEXES instrument was mounted on the Gemini North telescope in March 2017, improving the diffraction-limited spatial resolution by a factor of ~2.5 compared with that offered by the IRTF. This Gemini spatial scale sensitivity study was performed in support of the longer-termed Jupiter monitoring being performed at the IRTF. We find that the spatial resolution afforded by the smaller 3 m IRTF is sufficient to spatially resolve the 3D structure of Jupiter's equatorial stratospheric oscillation by comparing the thermal retrievals of IRTF and Gemini observations. We then performed numerical simulations in a general circulation model to investigate how the structure of Jupiter's stratosphere responds to changes in the latitudinal extent of wave forcing in the troposphere. We find our simulations produce a lower limit in meridional wave forcing of ±7° (planetocentric coordinates) centered about the equator. This likely remains constant over time to produce off-equatorial thermal oscillations at ±13°, consistent with observations spanning nearly four decades.</div

Super-adiabatic temperature gradient at Jupiter's equatorial zone and implications for the water abundance

The temperature structure of a giant planet was traditionally thought to be an adiabat assuming convective mixing homogenizes entropy. The only in-situ measurement made by the Galileo Probe detected a near-adiabatic temperature structure within one of Jupiter's 5μm hot spots with small but definite local departures from adiabaticity. We analyze Juno's microwave observations near Jupiter's equator (0– 5 oN) and find that the equatorial temperature structure is best characterized by a stable super-adiabatic temperature profile rather than an adiabatic one. Water is the only substance with sufficient abundance to alter the atmosphere's mean molecular weight and prevent dynamic instability if a super-adiabatic temperature gradient exists. Thus, from the super-adiabaticity, our results indicate a water concentration (or the oxygen to hydrogen ratio) of about 4.9 times solar with a possible range of 1.5– 8.3 times solar in Jupiter's equatorial region

Residual Study: Testing Jupiter Atmosphere Models Against Juno MWR Observations

The Juno spacecraft provides unique close‐up views of Jupiter underneath the synchrotron radiation belts while circling Jupiter in its 53‐day orbits. The microwave radiometer (MWR) onboard measures Jupiter thermal radiation at wavelengths between 1.37 and 50 cm, penetrating the atmosphere to a pressure of a few hundred bars and greater. The mission provides the first measurements of Jupiter's deep atmosphere, down to ~250 bars in pressure, constraining the vertical distributions of its kinetic temperature and constituents. As a result, vertical structure models of Jupiter's atmosphere may now be tested by comparison with MWR data. Taking into account the MWR beam patterns and observation geometries, we test several published Jupiter atmospheric models against MWR data. Our residual analysis confirms Li et al.'s (2017, https://doi.org/10.1002/2017GL073159) result that ammonia depletion persists down to 50–60 bars where ground‐based Very Large Array was not able to observe. We also present an extension of the study that iteratively improves the input model and generates Jupiter brightness temperature maps which best match the MWR data. A feature of Juno's north‐to‐south scanning approach is that latitudinal structure is more easily obtained than longitudinal, and the creation of optimum two‐dimensional maps is addressed in this approach