Sanchez-Lavega A, Lecacheux J, Colas F, Laques P
Science. 1993 Apr 16;260(5106):329-32. doi: 10.1126/science.260.5106.329.
Ground-based observations of two conspicuous features near the north pole of Saturn, the polar vortex and the hexagonal wave structure, were made from July 1990 to October 1991, 10 years after their discovery. During this period the polar spot drifted in longitude, relative to system III, by -0.0353 degrees per day on average. Superimposed on this mean motion, the spot also underwent short-term rapid excursions in longitude of up to approximately 14 degrees at rates of up to approximately 1 degrees per day. The spot also exhibited irregular variations in its latitude location. A combination of these data together with those obtained by Voyager 1 and 2 in 1980 and 1981 shows that the spot drifted -0.0577 degrees per day for the 11-year interval from 1980 to 1991. The large lifetime of both features indicates that they are insensitive to the strong variations in the seasonal heating of the cloud layers in the upper polar atmosphere.
在土星北极附近两个显著特征——极地涡旋和六边形波状结构被发现10年后，于1990年7月至1991年10月期间进行了地面观测。在此期间，相对于系统III，极斑在经度上平均每天漂移-0.0353度。叠加在这种平均运动之上，极斑在经度上还经历了短期快速偏移，速度高达每天约1度，偏移量可达约14度。极斑在纬度位置上也表现出不规则变化。这些数据与1980年和1981年旅行者1号和2号获得的数据相结合，表明在1980年至1991年的11年间隔内，极斑每天漂移-0.0577度。这两个特征的长时间存在表明它们对极地高层大气云层季节性加热的强烈变化不敏感。
