Mixed Layer Salinity Balance in the Eastern Tropical Indian Ocean

Zhang, Zhengbei; Wang, Jing; Yuan, Dongliang

doi:10.1029/2021jc018229

Cited by 6 publications

(5 citation statements)

References 78 publications

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“…While river input and freshwater flux play a dominant role in the west‐east contrast of salinity in the IO (Figure 1), horizontal advection is crucial for redistributing low‐salinity water (Cronin & McPhaden, 1998; Wu et al., 2007; Zhang et al., 2022). Most precipitation is concentrated in the summer monsoon season, and river input reaches its peak in autumn, leading to significant seasonal variability in salinity (Chowdary et al., 2016; Rao & Sivakumar, 2003; Sengupta et al., 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The salinity variability in the northeastern Indian Ocean (IO) is a matter of great concern due to the significant influx of freshwater and its profound impact on oceanic and climatic dynamics. The substantial river input and positive air‐sea freshwater flux (Zhang et al., 2022) result in the sea surface salinity (SSS) of the northeastern IO being among the lowest globally (Akhil et al., 2014; Han, McCreary, & Kohler, 2001; Howden & Murtugudde, 2001; Yu & McCreary, 2004). The low SSS and haline stratification create a barrier layer between the mixed layer and thermocline, preventing vertical mixing and enhancing surface heating (Maes et al., 2002; Shenoi et al., 2005; Thompson et al., 2006; Vialard et al., 2002).…”

Section: Introductionmentioning

confidence: 99%

“…

The salinity variability in the northeastern Indian Ocean (IO) is a matter of great concern due to the significant influx of freshwater and its profound impact on oceanic and climatic dynamics. The substantial river input and positive air-sea freshwater flux (Zhang et al, 2022) result in the sea surface salinity (SSS) of the northeastern IO being among the lowest globally (

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mentioning

confidence: 99%

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Observed Extreme Freshening in the Central Andaman Sea Induced by Strong Positive Indian Ocean Dipole

Liu,

Sangmanee,

et al. 2024

JGR Oceans

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The Indian Ocean Dipole (IOD) has been extensively studied for its significant impact on salinity distribution in tropical regions. However, its off‐equatorial influence in the northeastern Indian Ocean (IO) has received limited documentation thus far. In October 2019, a buoy in the central Andaman Sea (AS) observed an extreme freshening event that resulted in intensified upper‐ocean stratification and increased internal wave activities. The salt budget evaluation revealed the dominant role of horizontal advection. Interannual variability in autumn and winter sea surface salinity (SSS) showed a significant correlation with the IOD. Extreme freshening was observed exclusively during strong positive IOD (pIOD) years. This freshening primarily resulted from the outflow of low‐salinity water from the northeastern coast of the AS, driven by an anomalous anti‐cyclonic coastal‐trapped circulation exclusive to strong pIODs in the northeastern IO. This circulation tends to hinder southward freshwater transport in the western region while enhancing it in the eastern region. This circulation pattern is primarily influenced by Kelvin wave forcing, which is triggered by robust equatorial easterly anomalies that are typically more pronounced during strong pIOD events and weaker during weak pIOD events. The anticipated increase in the frequency of extreme freshening events due to the greenhouse warming has the potential to significantly modify the salinity distribution and freshwater transport in the future.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Observed Extreme Freshening in the Central Andaman Sea Induced by Strong Positive Indian Ocean Dipole

Liu,

Sangmanee,

et al. 2024

JGR Oceans

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“…Interannual variations in equatorial winds associated with the IOD and ENSO dominate the currents in the equatorial Indian Ocean (EIO), which could influence the interannual variations in the salinity distribution in the BoB [10]. After the summer monsoon, the zonal winds are mostly westerlies over the EIO, forming strong surface eastward currents, referred to as Wyrtki jets [11].…”

Section: Introductionmentioning

confidence: 99%

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Chen,

Qiu,

Jing

et al. 2024

Remote Sensing

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In this study, we investigate the connection between planetary equatorial waves, modulated by the Indian Ocean dipole (IOD) and El Niño Southern Oscillation (ENSO), and the interannual variabilities of the salinity distribution in the Bay of Bengal (BoB) in October–December (OND), along with its associated dynamics, using satellite and reanalysis datasets. In OND 2010 and 2016 (1994, 1997, 2006, and 2019), positive (negative) sea surface salinity anomalies (SSSAs) were distributed in the eastern equatorial Indian Ocean (EIO) and Andaman Sea. Moreover, the southward movement of negative (positive) SSSAs along the eastern Indian coast was observed. This phenomenon was caused by large-scale anomalous currents associated with zonal wind over the EIO. During OND 2010 and 2016 (1994, 1997, 2006, and 2019), due to anomalous westerlies (easterlies) over the EIO and anomalous downwelling (upwelling) Kelvin waves, the strengthened (weakened) Wyrtki jet and the basin-scale anomalous cyclonic (anticyclonic) circulation in the BoB gave rise to positive (negative) SSSAs within the eastern EIO and Andaman Sea. In addition, the intensified (weakened) eastern Indian coastal currents led to the southward movement of negative (positive) SSSAs. It is worth noting that downwelling Kelvin waves reached the western coast of India during OND 2010 and 2016, while upwelling Kelvin waves were only confined to the eastern coast of India during OND 1994, 1997, 2006, and 2019. Furthermore, westward salinity signals associated with reflected westward Rossby waves could modulate the spatial pattern of salinity. The distribution of salinity anomalies could potentially influence the formation of the barrier layer, thereby impacting the sea surface temperature variability and local convection.

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“…The former is due to anomalous zonal advection of high‐salinity water triggered by the easterly wind anomalies (Li et al., 2016; Vinayachandran & Nanjundiah, 2009; Zhang et al., 2013). The latter is mainly dominated by precipitation and ocean dynamics processes (Kido et al., 2019a, 2019b; Zhang, Du, & Qu 2016; Zhang, Feng, et al., 2016; Zhang et al., 2022). Due to the lack of vertical upwelling observations, the observational results show that the precipitation decrease dominates the increase of salinity in the SETIO (Kido & Tozuka, 2017; Li et al., 2016; Zhang, Du, & Qu 2016; Zhang, Feng, et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Response of Sea Surface Salinity to Extreme Positive and Negative Indian Ocean Dipole in the Southern Tropical Indian Ocean

Sun

Zhang

et al. 2022

JGR Oceans

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Based on the Argo and multi‐satellite observations, this study investigates the asymmetric response of sea surface salinity (SSS) to two extreme positive and negative Indian Ocean Dipole (IOD) events in the southern tropical Indian Ocean (TIO). During positive IOD events, the easterly wind anomalies trigger zonal freshwater advection along the equator, decreasing SSS, while cold sea surface temperature (SST) depress the convective precipitation in the southeastern TIO (SETIO), increasing the SSS. Contrast SSS anomalies along the equator and in the SETIO show opposite phases during positive and negative IOD events. These SSS anomalies have enhanced in recent years, reaching the strongest in the extreme negative IOD in 2016 and positive IOD in 2019. The case study shows that positive SSS anomalies occurred in the southern TIO during both positive and negative IOD events in 2016 and 2019, suggesting significant asymmetry in SSS. Analysis of the mixed layer salinity budget shows that the local precipitation and the entrainment associated with the upwelling Rossby waves played an essential role in the SSS increase in 2016, while the decreased precipitation and horizontal advection caused by the westward South Equatorial Current contributed to the SSS increase in 2019. Further analyses suggest that SSS response is more sensitive to thermocline shoaling than deepening, and SSS response to precipitation is greater at shallower mixed layer than at deeper ones, which is the main reason for the asymmetric response of the SSS to negative and positive IOD events.

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Mixed Layer Salinity Balance in the Eastern Tropical Indian Ocean

Cited by 6 publications

References 78 publications

Observed Extreme Freshening in the Central Andaman Sea Induced by Strong Positive Indian Ocean Dipole

Observed Extreme Freshening in the Central Andaman Sea Induced by Strong Positive Indian Ocean Dipole

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Asymmetric Response of Sea Surface Salinity to Extreme Positive and Negative Indian Ocean Dipole in the Southern Tropical Indian Ocean

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