‘Aquarius’ Maps Ocean Salinity Fine-scale Structure
O. Melnichenko1, P. Hacker1,2, N. Maximenko1, and J. Potemra1,2
1IPRC, 2HIGP
SPURS
Fig. 2. Time-latitude plot of SSS
measured by Aquarius along the
track shown in Fig. 1. To filter
out measurement noise, the raw
along-track data are smoothed
with a moving Hanning window
of 50-km half-width, The white
dashed line approximates the
seasonal march of ITCZ.
Aquarius
Fig. 1. September 2011 mean SSS field from
Aquarius. The white dotted line shows the
Aquarius repeat track that passes through the
SPURS array (star), which is providing much
needed in situ data for Aquarius validation as
well as supporting SPURS research goals.
(SSS in psu)
Argo
Fig. 3. September 2011 mean SSS field from in
situ Argo float data (IPRC product).
Since August 2011, the Aquarius satellite is providing the scientific
community with detailed space-based measurements of sea surface salinity
(SSS). IPRC scientists have developed a method for deriving quality
salinity information from the raw data. By combining the optimal
interpolation technique with a new approach that uses long-wave error
correlation for each Aquarius beam and cycle, they are able to reduce interbeam biases and the differences in measurements along the ascending
(northward) and descending (southward) tracks.
The analysis for the North Atlantic (Fig. 1) demonstrates an SSS pattern
consistent with the seasonal cycle, which is most pronounced in the tropical
band and off the north-east coast of South America and shows that the SSS
structures have sharp spatial gradients that can change on time scales as
short as one month (Fig. 2). The match between Aquarius and Argo
profiling float array (Fig.3) observations for SSS in the North Atlantic lend
validity to the Aquarius measurements. By supplying much higher
resolution details of SSS structures not available from Argo, the Aquarius
satellite advances the Global Ocean Observing System to a new level.