Jupiter in 2013/14: Interim report no.7: 

The Great Red Spot in 2013/14:  Faster shrinkage and evidence for faster wind speed

by John Rogers (BAA), 2014 March 30

Summary:

In 2013/14, the Great Red Spot (GRS) is smaller than ever before, with a length of 13.6 deg. (15860 km).  It also has an exceptionally short circulation period: 3.6 (±0.2) days.  The inferred wind speed, 144 (±14) m/s, is faster than any previous measurement of the mean peak wind except for one (by Galileo in 2000), but the difference is less than the uncertainties.  If the wind speed has truly accelerated, in 2013/14 as in 2000, this may be due to influx of vorticity from the STBn jet spots which are being disrupted along the edge of the GRS.

Report text, including mini-figures (PDF):  Report-on-GRS_no7_2014Mar_with-Figs_final

Figures (full size: ZIP file):  Report-no7_GRS_Figures