Origins of biweekly sea surface temperature variability in the eastern
equatorial Pacific and Atlantic
Abstract
Biweekly sea surface temperature (SST) variability significantly
contributes to over 50% of the intraseasonal variability in the eastern
equatorial Pacific (EEP) and Atlantic (EEA). Our study investigates this
biweekly variability, employing a blend of in-situ and reanalysis
datasets. The research identifies biweekly signals in SST, meridional
wind, and ocean currents, notably in September-November in EEP and
June-August in EEA. Biweekly southerly (northerly) drives simultaneous
northward (southward) ocean currents in EEP, but with a 1-2-day phase
delay in EEA. Consequently, these currents lead to SST anomalies with a
3-4-day lag in both EEP and EEA due to the presence of the cold tongue.
The study reveals the origin of biweekly wind fluctuations in the
western Pacific for EEP and the subpolar Pacific for EEA, connected by
Rossby waves validated through a linearized non-divergent barotropic
model. This research affirms the influence of subtropical and subpolar
atmospheric forcing on equatorial SST.