The first successful numerical forecasts of El Niño–Southern Oscillation (ENSO) were demonstrated in the 1980s by Mark Cane and colleagues at the Lamont–Doherty Earth Observatory. Since then, the tropical climate dynamics community has worked relentlessly to improve those forecasts, largely due to the well–known impacts of El Niño and La Niña events on weather, ecosystems and society around the world.
An equally daunting challenge—measuring the surface salinity of the global ocean from space—became a demonstrated scientific capacity in 2011 with the launch of the joint US–Argentine satellite mission known as Aquarius/SAC–D. Near–surface ocean salinity influences the density of the upper ocean, which in turn influences vertical stratification and wave properties that are at the heart of ENSO dynamics.
Hackert et al.  show that space–borne salinity observations help constrain the initial state of the tropical Pacific Ocean in ways that conventional observations do not, leading to improved forecasts of ENSO events in a coupled model at all lead times from one month to one year. Like the weather and other extreme climate anomalies, ENSO forecasts will never be perfect, but this study clearly illustrates the immediate societal value of sustained satellite observations of the ocean.
Citation: Hackert, E. C., Kovach, R. M., Busalacchi, A. J., & Ballabrera‐Poy, J. . Impact of Aquarius and SMAP satellite sea surface salinity observations on coupled El Niño/Southern Oscillation forecasts. Journal of Geophysical Research: Oceans, 124. https://doi.org/10.1029/2019JC015130
—Kristopher B. Karnauskas, Editor, JGR: Oceans