Diverse variability of surface chlorophyll during the evolution of Gulf Stream rings

Abstract

We investigate how the near-surface chlorophyll (CHL)-a evolves in Gulf Stream (GS) warm-core rings (WCRs) and cold-core rings (CCRs) using multi-platform satellite observations. Averaged CHL anomaly (CHLA) within the rings exhibits both positive and negative linear trends during the evolution of the WCRs while negative trends dominate in CCRs. This difference is associated with a variety of physical processes occurring during the evolution process. Meanwhile, eddy-centric analysis reveals four spatial patterns of CHLA long-term trends, some of which highlights the importance of rings in shaping surface CHL. Short-term fluctuations of CHLA in WCRs and CCRs are closely correlated with mixed layer depth and sea surface temperature anomaly and highlight the complex interplay between multiple mechanisms. In addition, we find higher concentration CHL in some WCRs than that in CCRs during the same season, providing an alternative view of the characteristics of the surface ecosystem in Gulf Stream rings.