The Madden‐Julian oscillation detected in Aquarius salinity observations

Abstract

[1] The Madden-Julian Oscillation (MJO) impacts a wide range of weather and climate phenomena. Current global coupled ocean-atmospheric general circulation models exhibit considerable shortcomings in representing and predicting the MJO, specifically its initiation, due to a lack of in situ observations. Here we show, for the first time, that the MJO propagation can be detected from the newly launched NASA Aquarius Salinity mission. The magnitude and extent of sea surface salinity (SSS) variations during the MJO is established, providing a useful tool for data assimilation into models to correctly represent both oceanic and atmospheric processes during intraseasonal variations. Salinity observation allows for atmospheric conditions to be inferred from freshwater flux, on which surface salinity is highly dependent. Increased observations of global SSS from the Aquarius mission will be particularly valuable in remote regions of the tropics and will increase our dynamical understanding and advance prediction of the MJO through model improvement.

Assessment of Aquarius Sea Surface Salinity

“…Figure 6b shows the global averages of regional temporal STD values of Aquarius SSS with respect to Argo-SIO SSS for various spatial scales. The difference between Figure 6a [4,21], Madden-Julian Oscillation [22,23], El Niño-Southern Oscillation [24], and Indian Ocean Dipole [25]. It is noteworthy that the global average STD value for non-seasonal SSS anomalies is less than 0.1 psu for 1 • × 1 • scale and 0.04 psu for 10 • × 10 • scale.…”

“…Figure 6c,d shows the global average of STD values for composite seasonal anomalies and nonseasonal anomalies (referenced to the composite seasonal cycle) of the SSS differences between Aquarius and Argo-SIO. The non-seasonal anomalies are associated with the differences between Aquarius and Argo-SIO in representing non-seasonal signals associated with phenomena such as tropical instability waves [4,21], Madden-Julian Oscillation [22,23], El Niño-Southern Oscillation [24], and Indian Ocean Dipole [25]. It is noteworthy that the global average STD value for non-seasonal SSS anomalies is less than 0.1 psu for 1° × 1° scale and 0.04 psu for 10° × 10° scale.…”

Sea surface salinity variability in response to the Congo river discharge

“…Since the launch of Aquarius in June 2011, there have been several early scientific investigations demonstrating the use of Aquarius SSS data on topics ranging from the global water cycle (Lagerloef et al, 2010), to Tropical Instability Waves (Lee et al, 2012), the MaddenJulian Oscillation (Grunseich et al, 2013), and the barrier layer in the equatorial Pacific Ocean (Qu et al, 2014). In addition to the large-scale ocean circulation, the Aquarius mission also has a secondary scientific objective to detect SSS patterns and changes in coastal areas where the SSS variability has a relatively large signal (significantly greater than 0.2 psu) and covers a region sufficiently far from the coastline to avoid land contamination (Koblinsky et al, 2003;LeVine et al, 2004).…”

Variability of sea surface salinity in the tropical Indian Ocean as inferred from Aquarius and in situ data sets

“…These authors showed that even though the quality of Aquarius-derived SSS is excellent over most parts of the global ocean, the error is somewhat higher over the TIO. Grunseich, Subrahmanyam, and Wang (2013) showed that Aquarius-based SSS can detect the propagation of Madden-Julian oscillation. SSS from the SMOS and Aquarius missions also showed a positive impact on an ocean general circulation model simulation (Chakraborty et al 2014;Vinogradova et al 2014).…”