Control of salinity stratification on recent increase in tropical cyclone intensification rates over the postmonsoon Bay of Bengal

Fan, Kewei; Wang, Xidong; He, Zikang

doi:10.1088/1748-9326/ab9690

Cited by 11 publications

(11 citation statements)

References 60 publications

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“…ORAS5 has a horizontal resolution of 0.25° × 0.25° and 75 vertical levels, with the first 31 levels increasing from 1 m at the surface to 200 m in the deep ocean. Compared to the previous version ORAS4 (Balmaseda et al., 2013), ORAS5 has significantly improved the ocean climate state and the variability in terms of SST and sea level, and it has been widely used in previous studies of salinity and BL in the Indian Ocean (Fan et al., 2020; Z. Li et al., 2021; Nie et al., 2020; Roman‐Stork et al., 2020).…”

Section: Methodsmentioning

confidence: 99%

Dynamics of the Barrier Layer Dipole in the Equatorial Indian Ocean

Li,

Han,

Liao

et al. 2024

JGR Oceans

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The barrier layer (BL) significantly impacts the upper ocean circulation and thermodynamic structure by inhibiting the heat and momentum exchange between the mixed layer (ML) and the subsurface layer. There exist sea surface temperature and salinity dipole modes in the tropical Indian Ocean, however, a BL dipole mode has not yet been identified. Using the latest observations and ocean reanalysis, here we show a robust BL dipole mode in the central and eastern equatorial Indian Ocean, which is highly correlated with the Indian Ocean Dipole (IOD) events. Composite analysis shows that the BL thickness anomalies peak in autumn and are much larger during positive IOD events than during negative IOD events. We show that a positive BL dipole phase is characterized by positive BL thickness anomalies in the central equatorial Indian Ocean and negative BL thickness anomalies in the eastern equatorial Indian Ocean, and vice versa for a negative BL dipole phase. During positive IOD events, negative surface salinity anomalies slightly affect the ML depth along the equatorial Indian Ocean. Positive subsurface temperature anomalies deepen the isothermal layer (IL) in the central equatorial Indian Ocean and strong negative subsurface temperature anomalies significantly lift the IL in the eastern equatorial Indian Ocean, controlling the BL thickness anomalies and forming a positive BL dipole pattern. This operates in an opposite direction during negative IOD events. Our study shows a close relationship between the BL dipole and the IOD and has far‐reaching implications for better understanding and predicting the IOD events.

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Section: Methodsmentioning

confidence: 99%

Dynamics of the Barrier Layer Dipole in the Equatorial Indian Ocean

Li,

Han,

Liao

et al. 2024

JGR Oceans

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“…This results in the accumulation of heat in the Bay of Bengal leading to an increase in the ocean heat content (Anandh et al 2018). Further, it is observed that in the recent decade (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015), there is a fourfold increase in the rapid intensification rate of the post-monsoon Bay of Bengal cyclones (Fan et al 2020). This increase in the rapid intensification cases is associated with the northeastward shift of the cyclone tracks.…”

Section: Observed and Projected Changes In The Ocean-cyclone Interactionmentioning

confidence: 99%

“…Due to this northeastward shift in the cyclone track, now more cyclones are reaching the northern Bay of Bengal that has low salinity and is highly stratified. Due to the higher stratification, the cyclone-induced cold wake gets suppressed resulting in favorable ocean conditions for the cyclone to gain more energy and undergo rapid intensification (Fan et al 2020).…”

Section: Observed and Projected Changes In The Ocean-cyclone Interactionmentioning

confidence: 99%

A review of ocean-atmosphere interactions during tropical cyclones in the north Indian Ocean

Singh

Roxy

2022

Earth-Science Reviews

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“…N 2 -temperature is computed by using 0-200 m depth-averaged salinity in the N 2 computation thereby removing the effects from changes in salinity. N 2 -salinity is then estimated as N 2 minus N 2 -temperature (Fan et al, 2020).…”

Section: ∂T ∂Tmentioning

confidence: 99%

Interactions Between a Marine Heatwave and Tropical Cyclone Amphan in the Bay of Bengal in 2020

et al. 2022

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Interactions are diagnosed between a marine heatwave (MHW) event and tropical super cyclone Amphan in the Bay of Bengal. In May 2020, an MHW developed in the Bay of Bengal driven by coupled ocean-atmosphere processes which included shoaling of the mixed layer depth due to reduced wind speed, increased net surface shortwave radiation flux into the ocean, increased upper ocean stratification, and increased sub-surface warming. Ocean temperature, rather than salinity, dominated the stratification that contributed to the MHW development and the subsurface ocean warming that also increased tropical cyclone heat potential. The presence of this strong MHW with sea surface temperature anomalies >2.5°C in the western Bay of Bengal coincided with the cyclone track and facilitated the rapid intensification of tropical cyclone Amphan to a super cyclone in just 24 h. This rapid intensification of a short-lived tropical cyclone, with a lifespan of 5 days over the ocean, is unprecedented in the Bay of Bengal during the pre-monsoon period (March-May). As the cyclone approached landfall in northern India, the wind-induced mixing deepened the mixed layer, cooled the ocean's surface, and reduced sub-surface warming in the bay, resulting in the demise of the MHW. This study provides new perspectives on the interactions between MHWs and tropical cyclones that could aid in improving the current understanding of compound extreme events that have severe socio-economic consequences in affected countries.

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Control of salinity stratification on recent increase in tropical cyclone intensification rates over the postmonsoon Bay of Bengal

Cited by 11 publications

References 60 publications

Dynamics of the Barrier Layer Dipole in the Equatorial Indian Ocean

Dynamics of the Barrier Layer Dipole in the Equatorial Indian Ocean

A review of ocean-atmosphere interactions during tropical cyclones in the north Indian Ocean

Interactions Between a Marine Heatwave and Tropical Cyclone Amphan in the Bay of Bengal in 2020

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