Juno Dives Deep Into a Brown Barge

The color-enhanced image on the left is from the JunoCam imager aboard NASA's Juno spacecraft and has been annotated to depict the anticyclonic (counterclockwise) rotation of one of Jupiter's intriguing atmospheric phenomena – a long, brown oval cyclonic region known as a "brown barge." The graphic on the right highlights the large-scale structure of the brown barge as seen by the spacecraft's microwave radiometer (MWR) instrument. Data for the image and the microwave radiometer results were collected during a low flyby of Jupiter. Brown barges usually lie within Jupiter's dark North Equatorial Belt, although they are sometimes found in the similarly dark South Equatorial Belt as well. They can often be difficult to detect visually because their color blends in with the dark surroundings. Brown barges usually dissipate after the entire cloud belt undergoes an upheaval and reorganizes itself. Juno is providing the first glimpses of the detailed structure within such a barge. The radiometer data was acquired from the six channels of MWR. Each MWR channel peers progressively deeper below the visible cloud tops. In fact, the MWR instrument enables Juno to see deeper into Jupiter than any previous spacecraft or Earth-based observations. Unlike Earth, which as a solid surface, Jupiter is a gas giant with no discernable solid surface. So the planetary science community has defined the "base" of Jupiter's atmosphere as the location where its pressure is equivalent to 1 bar. The bar is a metric unit of pressure that, at 14.5 pounds per square inch, is slightly less than the average atmospheric pressure on Earth at sea level. The numbers to the left of each layer of MWR data indicates the pressure that is present at the location in the atmosphere where the MWR reading occurred. The distance measurements to the right of each layer of MWR data provides the distance – either above or below the 1 bar level – at which the corresponding MWR measurement was taken. For context, the top layer in the figure is a visible-light image depicting Jupiter's different levels of clouds, with an average altitude about 6 miles above the 1 bar pressure region. https://photojournal.jpl.nasa.gov/catalog/PIA24974