Ocean temperature data obtained from the central Arctic Ocean during 1995--1999 show interannual changes in the temperature of the warm Atlantic Water core. Widespread warming continued from 1995 until 1998 but had ceased during 1998--1999 and was replaced by a slight cooling. The timing of these changes differed regionally, as the warming had occurred prior to 1995 in the Nansen and Amundsen basins, and between 1995 to 1998 in the Makarov Basin. The regional phase differences are consistent with advection along mid-ocean ridges from the Eurasian margin slope current, which provides the source for warm Atlantic Water. Anomalous behaviors were associated with the Arctic Mid-Ocean and Lomonosov ridges and probably reflected the presence of overlying topographically trapped circulations. ¿ 2001 American Geophysical Union