Jovan sent in the links below – www.missionjuno.swri.edu/news/juno-probes-depths-of-great-red-spot … and www.space.com/39066-jupiter-great-red-spot-depth-juno-spacecraft.html … data collected by NASAs Juno spacecraft indicates that the great red spot penetrates deep below the upper atmosphere of Jupiter. The red spot is a giant oval of crimson coloured clouds that race counter clockwise around the perimeter of the anomaly ….
… the great red spot is a thord of the size it was in the 19th century (but these were earth based measurements). The actual NASA news release also says the deep roots of the red spot penetrate down into a much warmer areas of Jupiter's atmosphere and that warm base explains the ferocious winds that we see at the top of the atmosphee. See also www.nasa.gov/juno