Interannual Variability of Annual Minimum Sea Surface Temperature in the Eastern China Seas

An understanding of ocean temperature variability and extremes is a prerequisite for assessing the resilience of marine ecosystems. While significant attention has been paid to the impacts of extremely high temperatures, extremely low temperatures have received comparatively less consideration. This study investigated interannual variability in the annual minimum sea surface temperature (T _min ) in the Eastern China Seas from 1985 to 2022. The results reveal significant spatial and temporal patterns in T _min and its timing. Distinct regional differences were observed between warming areas influenced by warm currents and cooling areas dominated by coastal currents. Both regions showed positive correlations between T _min and annual minimum air temperature (AirT _min ), as well as between the occurrences of T _min AirT _min , and annual minimum wind (V). However, key regional differences were also observed. From December through March, T _min was closely linked to air temperature and longwave radiation in warming regions. In cooling regions, T _min was influenced by wind (V), latent heat flux (Q _LH ) and sensible heat flux (Q _SH ), with December conditions affecting T _min and February conditions impacting T _min timing. The study also showed that low T _min values led to increased chlorophyll levels and a high likelihood of marine cold spells. These findings offer important insights into the dynamics of regional sea surface temperature and help to understand the effects of climate change on marine ecosystems.