The merger of two giant anticyclones in the atmosphere of Jupiter

Two giant ovals in Jupiter's southern atmosphere, vortices of counterclockwise-rotating winds, merged in a 3-week period, starting in March 2000. One of the ovals called FA was more than 60 years old; the other called BE was the product of two 60-year-old ovals (BC and DE) that merged in 1998 (A, Sanchez-Lavega ef al. 1999, Icarus 142, 116-124). The merger took place when the ovals were southeast of the Great Red Spot and after the disappearance of a smaller clockwise-rotating oval midway between them. The interaction began when the high-altitude oval clouds showed counterclockwise rotation about each other, followed by coalescence and shrinking. The interaction in deeper clouds did not include mutual rotation, but there was evidence of complex cloud structure during the merger. (C) 2001 academic Press.