かいりゅう海流kairyuu
1.

A persistent flow of seawater that moves in a consistent direction, influenced by factors such as wind patterns and uneven solar heating, which can vary seasonally, particularly near the equator.

2.

A broad and steady movement of ocean water that plays a significant role in shaping climatic conditions, navigation routes, and fishing grounds.

Example:

海流に変化が起きたのだろうか。