Decadal phase change in large‐scale sea level and winds in the Indo‐Pacific region at the end of the 20th century

Abstract

Satellite observations of sea surface height (SSH) and wind stress for the period of 1993–2006 reveal a near‐coherent large‐scale decadal variability in much of the Indo‐Pacific region with a phase change at the turn of the 20th century. Trade wind variations in the tropical Pacific and South Indian Ocean are anti‐correlated with each other as are SSH differences across these two basins, implying anti‐correlated variation of the subtropical cells in the two oceans. Decadal changes in large‐scale SSH in the extra‐tropics are mostly associated with well‐defined patterns of wind stress curl indicating a near‐coherent decadal variation in the strength of subtropical and subpolar gyres. Together, these variations reflect a linkage in the circulation of the Pacific and Indian Oceans via atmospheric and oceanic bridges. The phase change in the tropical Pacific tends to occur earlier than elsewhere, suggesting a potential role of the tropical Pacific in regulating decadal variability of the entire region.