Atmospheric waves and dynamics beneath Jupiter's clouds from radiowavelength observations

Abstract

We observed Jupiter at wavelengths near 2 cm with the Karl G. Jansky Very Large Array 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. We have examined the data for atmospheric waves and observed a prominent bright belt of radio hotspot features near 10N, likely connected to the same equatorial wave associated with the 5-micron hotspots. We conducted a passive tracer power spectral wave analysis for the entire map. 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 GRS is also very prominent and has a noticeable meridional asymmetry and we compare it, and nearby storms, with optical images. We 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 our observation complemented the radio wavelength map to investigate dynamics of the equatorial region in Jupiter's atmosphere. We 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 micron 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.