Satellites play an important role in assembling a complete and effective observing system for the tropical Pacific. While in situ observations such as Argo and the TMA offer high temporal resolution and subsurface information unattainable by satellites, space-borne platforms offer unmatched coverage and horizontal resolution, of particular importance over the ocean, where in situ measurement platforms are inevitably sparse.
Satellite data provide important context for observations made from ships, moorings, Argo floats and other autonomous platforms. For example, observations from the OCO-2 (atmospheric carbon) satellite, when combined with moored pCO2 data from the tropical Pacific, have improved our understanding of the timing of global changes in atmospheric CO2 linked to El Niño events (Chatterjee et al., 2017). As for SST, winds and altimetry, observations from other components of the observing system contribute important validation data for satellite ocean color and atmospheric CO2.