Decadal Variability of the Barrier Layer and Forcing Mechanism in the Bay of Bengal

Pang, Si; Wang, Xidong; Liu, Hailong; Zhou, Guidi; Fan, Kewei

doi:10.1029/2018jc014918

Cited by 12 publications

(4 citation statements)

References 64 publications

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“…In the western Pacific warm pool, sea surface freshwater forcing, including the heavy rain under ITCZ and high salinity water subduction from subtropics, are the dominant processes for the BL formation (Anderson et al., 1996; Bosc et al., 2009). Positive BLT anomalies along the eastern and northern coast of the Bay of Bengal during a positive Pacific Decadal Oscillation (PDO) are associated with deepening ILD, referring to enhancing shoreward Ekman transport (Pang et al., 2019). As discussed in Section 4, the BL formations in different seasons are attributed to different processes.…”

Section: Physical Processes and Driving Mechanismsmentioning

confidence: 99%

The Impact of the Eastern Pacific Fresh and Warm Pools on the Bimodal Seasonality of Barrier Layers

Chi

et al. 2023

JGR Oceans

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Observations of Argo profiles and TAO/TRITON array confirm the significant seasonality of the barrier layer (BL) and temperature inversion (TI) in the northeastern tropical Pacific (NETP). Statistical result of the occurrence based on the Argo profiles reveals a bimodal variability of the BL, with two peaks in July and October. This bimodal seasonality of BL is attributed to the out‐of‐phase variations of the eastern Pacific fresh and warm pools. The fresh and warm pools both expand westward from May to July, when the Inter‐Tropical Convergence Zone (ITCZ) becomes intense and broad. Heavy rainfall is the dominant contributor to the extension of the fresh and warm pools, leading to a high frequency of thick BL (40%). This frequent thick BL provides a precondition for its another development after August. The fresh pool is stable from August to November, while the warm pool contracts sharply. The cold tongue becomes active due to a prevailing trade wind and horizontal advection transports surface cold water to the northeastern warm pool. This cold advection deepens the isothermal layer and contributes to a frequent TI (30%) and thick BL (46%). The results suggest that the ITCZ rainfall and northward cold advection from equator dominate the upper layer stratification of NETP in summer and autumn, respectively.

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Section: Physical Processes and Driving Mechanismsmentioning

confidence: 99%

The Impact of the Eastern Pacific Fresh and Warm Pools on the Bimodal Seasonality of Barrier Layers

Chi

et al. 2023

JGR Oceans

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“…Here the ITD is calculated as the depth where seawater temperature decreases by 0.2 • C from the temperature at 10 m below the surface. This definition has been widely used in literature studies (de Boyer Montégut et al, 2004;Breugem et al, 2008;Pang et al, 2019). The HCT is defined over the upper 400 m as 0 −400 cρTdz, where T is temperature, c is specific heat capacity, and ρ is density.…”

Section: Eddy-induced Anomaliesmentioning

confidence: 99%

Mesoscale Eddy-Induced Ocean Dynamic and Thermodynamic Anomalies in the North Pacific

Zhou

Liu

et al. 2021

Front. Mar. Sci.

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Oceanic mesoscale eddies are associated with large thermodynamic anomalies, yet so far they are most commonly studied in terms of surface temperature and in the sense of composite mean. Here we employ an objective eddy identification and tracking algorithm together with a novel matching and filling procedure to more thoroughly examine eddy-induced thermodynamic anomalies in the North Pacific, their relationship with eddy amplitude (SSH), and the percentage of variability they explain on various timescales from submonthly to interannual. The thermodynamic anomalies are investigated in terms of sea surface temperature (SST), isothermal layer depth (ITD), and upper ocean heat content (HCT). Most eddies are weak in amplitude and are associated with small thermodynamic anomalies. In the sense of composite mean, anticyclonic eddies are generally warm eddies with deeper isothermal layer and larger heat content, and the reverse is true for cyclonic eddies. A small fraction of eddies, most probably subsurface eddies, exhibits the opposite polarities. Linear relationships with eddy amplitude are found for each of the thermodynamic parameters but with different level of scatter and seasonality. HCT-amplitude relation scatters the least and has the smallest seasonal difference, ITD-amplitude relation has the largest scatter and seasonality, while SST-amplitude relation is in between. For the Kuroshio and Oyashio Extension region, the most eddy-rich region in the North Pacific, eddies are responsible for over 50% of the total SSH variability up to the intra-seasonal scale, and ITD and HCT variability up to interannual. Eddy-induced SST variability is the highest along the Oyashio Extension Front on the order of 40–60% on submonthly scales. These results highlight the role of mesoscale eddies in ocean thermodynamic variability and in air-sea interaction.

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“…The development of barrier layers involves various physical mechanisms that regulate the ILD and MLD, including wind‐driven downwelling (e.g., Pang et al., 2019), horizontal advection of low salinity waters (e.g., George et al., 2019), net freshwater fluxes (e.g., Katsura et al., 2022), and relative vorticity (e.g., d’Ovidio et al., 2013). It is suggested that barrier layer thickness (BLT) extends from several meters to a hundred meters and varies temporally and spatially (de Boyer Montégut et al., 2007; Mignot et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

Observations of Barrier Layer Seasonal Variation in the Banda Sea

Ismail,

Karstensen,

Sulaiman

et al. 2024

JGR Oceans

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The Banda Sea is of crucial importance for the circulation of the world's oceans, as it is part of the connection between the Pacific to the Indian Ocean. One peculiarity of the upper ocean hydrography in the Banda Sea is the occurrence of barrier layers. The regionality and temporal variability of barrier layer thickness (BLT) in the Banda Sea are examined in this study utilizing in‐situ observations and ocean reanalysis output. It is found that a barrier layer occurs in over 90 % of the observational data profiles, and in over 72 % of those profiles, the BLT is shallower than 10 m. Furthermore, we find a seasonal cycle in BLT with a maximum thickness of about 60 m occurring during austral autumn and winter and coinciding with the presence of low saline waters fed by the regional river discharge and rainfall from the Java Sea and Makassar Strait. In addition, we identify the existence of a quasi‐permanent anticyclonic circulation cell in the Banda Sea that may support the trapping of surface freshwater by retention. The anticyclonic circulation is most likely wind‐driven because it coincides with the regional Ekman pumping pattern. Modulation of the anticyclone is via seasonal variability in the wind stress curl which in turn may explain the efficiency of freshwater retention and thus the BLT. The annual mean BLT distribution in the Banda Sea shows a preferential region of thickened barrier layers around 6o‐8oS and 124o‐126oE and resampling the pattern of the monthly mean climatology.

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Decadal Variability of the Barrier Layer and Forcing Mechanism in the Bay of Bengal

Cited by 12 publications

References 64 publications

The Impact of the Eastern Pacific Fresh and Warm Pools on the Bimodal Seasonality of Barrier Layers

The Impact of the Eastern Pacific Fresh and Warm Pools on the Bimodal Seasonality of Barrier Layers

Mesoscale Eddy-Induced Ocean Dynamic and Thermodynamic Anomalies in the North Pacific

Observations of Barrier Layer Seasonal Variation in the Banda Sea

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