Earth and Planetary Science
EPS Geophysics

EPS Astronomer Uses Radio Wavelengths to Observe Atmospheric Waves beneath Jupiter's Clouds

Thursday, February 16, 2017

Imke de Pater is co-author of “Atmospheric waves and dynamics beneath Jupiter’s clouds from radio wavelength observations.” The article was made available online 7 January 2017 in the journal Icarus.

The authors observed Jupiter at wavelengths near 2 cm with the Karl G. Jansky Very Large Array (VLA) in February 2015. These frequencies are mostly sensitive to variations in ammonia abundance and probe between ∼0.5−2.0 bars of pressure in Jupiter’s atmosphere; within and below the visible cloud deck which has its base near 0.7 bars. The resultant observed data were projected into a cylindrical map of the planet with spatial resolution of ∼1500  km at the equator. The authors also have examined the data for atmospheric waves and observed a prominent bright belt of radio hotspot features near 10°N, likely connected to the same equatorial wave associated with the 5-µm hotspots. They conducted a passive tracer power spectral wave analysis for the entire map and latitude regions corresponding to eastward and westward jets and compare our results to previous studies. The power spectra analysis revealed that the atmosphere sampled in our observation (excluding the NEB region) is in a 2-D turbulent regime and its dynamics are predominately governed by the shallow water equations. The Great Red Spot (GRS) is also very prominent and has a noticeable meridional asymmetry and we compare it, and nearby storms, with optical images. They find that the meridional radio profile has a global north-south hemisphere distinction and find correlations of it to optical intensity banding and to shear zones of the zonal wind profile over select regions of latitude. Amateur optical images taken before and after their observation complemented the radio wavelength map to investigate dynamics of the equatorial region in Jupiter’s atmosphere. They also find that two radio hotspots at 2 cm are well correlated with optical plumes in the NEB, additionally revealing they are not the same 5 µm hotspot features correlated with optical dark patches between adjacent plumes. This analysis exploits the VLA’s upgraded sensitivity and explores the opportunities now possible when studying gas giants, especially atmospheric dynamics of layers beneath upper level clouds.

Professor de Pater is jointly appointed in the Berkeley Departments of Earth & Planetary Science and Astronomy. She is former chair of the Astronomy Department.

For the full-length article please click here.