Aquarius Data Are Valuable for El Niño Forecasts
T. Qu , Y. T. Song, and C. Maes
At the eastern edge of the western Pacific
warm pool is a sea surface salinity (SSS) front
along the equator. The front’s zonal
displacement is a key feature of the El NiñoSouthern Oscillation (ENSO).
34.8 psu
34.8 psu
Fig. 1. Time-longitude distribution of SSS along the equator
from a) Aquarius and b) Argo
Aquarius
29C
34.8 psu
SOI
Fig. 2. Zonal displacement of 29 C isotherm (black) and 34.8 psu isohaline
(red) compared with SOI (green).
The new SSS observations from the satellite
instrument of Aquarius are consistent with Argo
observations, but depict this SSS front much
more precisely than Argo (Fig.1).
In both the Aquarius and Argo data, the zonal
displacements of the eastern edge of the warm
pool (29 C isotherm) and the SSS front (34.8 psu
isohaline) correspond well to ENSO phases, the
correlation with the Southern Oscillation Index
(SOI) exceeding 0.8 (Fig. 2).
Since at the eastern edge of the warm pool,
the east-west SSS gradient is more clearly
defined than the sea surface temperature
gradient, the Aquarius observations could
become a valuable tool for monitoring El Niño
and for improving predictions of El Niño onset.