Response of upper ocean and impact of barrier layer on Sidr cyclone induced sea surface cooling

Vissa, Naresh Krishna; Satyanarayana, A. N. V.; Kumar, B. Prasad

doi:10.1007/s12601-013-0026-x

Cited by 54 publications

(39 citation statements)

References 37 publications

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“…It infers that TC impact or influence is limited up to 400 km radius in the BoB region. The higher negative TCHPA during the slow movers could be attributed to (a) stronger TC intensity as shown in Figure b, and (b) vigorous turbulent mixing favoured by vertical current shear (Sengupta et al ., ; Vissa et al ., ). Figure b shows the mean TC intensity estimated for the slow, normal, and fast movers in terms of 10 m maximum sustained winds.…”

Section: Resultsmentioning

confidence: 97%

The response of ocean parameters to tropical cyclones in the Bay of Bengal

Busireddy

Ankur

Osuri

et al. 2019

Quart J Royal Meteoro Soc

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The Bay of Bengal (BoB) exhibits notable seasonal variations in tropical cyclone heat potential (TCHP), barrier layer thickness (BLT) and sea‐surface temperature (SST). These parameters also undergo profound changes in the presence of tropical cyclones (TCs). The composite structures of these ocean parameters as a function of the season of TC formation, intensity, and translation speed are unknown and are developed in the present study. Composite structures are examined based on 1,222 instantaneous samples from 83 TCs during 2003–2016 using INCOIS‐GODAS analyses. A BLT of 10–30 m and TCHP of 40–80 kJ/cm2 favours TC intensification in the central BoB. The multivariate regression of BLT and TCHP appears to be better for TC intensity up to 64 knots and is highly underestimated for the stronger TCs (>64 knots). The TC right‐rear sector experiences significant changes in TCHP anomaly (TCHPA) as the intensity increases. The TCHPA ranges ∼10–15, ∼20–25 and ∼25–30 kJ/cm2 when a TC is at Cyclone Storm (CS), Severe Cyclonic Storm (SCS) and Very SCS (VSCS) stages respectively. The maximum TCHPA is generally aligned along the TC track during the post‐monsoon season. Slow‐moving TCs produce maximum TCHPA cooling of ∼20 kJ/cm2 within 250 km storm radius in the rear sector, while it is less and away from the storm centre for normal and fast‐movers. The seasonal changes showed opposite relations between BLT and TCHP from pre‐ to post‐monsoon seasons during the TC intensification. TC‐induced SST cooling is maximum (∼0.5–1.2 °C) in the inner core for the strong (VSCS and above) and slow‐moving TCs. The cooling decreases with an increase in the translation speed and is more pronounced in the pre‐monsoon season. This study provides a baseline to verify and understand the limitations of the models, and also develop a climatological perspective of BoB TCs.

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Section: Resultsmentioning

confidence: 97%

The response of ocean parameters to tropical cyclones in the Bay of Bengal

Busireddy

Ankur

Osuri

et al. 2019

Quart J Royal Meteoro Soc

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“…The temperature at approximately 10 m depth was continuously higher than 29.5°C after 1 December and reached up to 30°C, resulting in a surface temperature The IL was drastically deepened just after the MJO arrived on 13 December, and the temperature inversion in the BL (Balaguru et al 2012;Cronin and McPhaden 2002;Mignot et al 2012;Thadathil et al 2002;Vinayachandran et al 2002;Vissa et al 2013b) is significant during the MJO passage. Meanwhile, the contour of the 29°C contour, which is indicative of the top of the thermocline, was continuously sinking throughout the observation period.…”

Section: Resultsmentioning

confidence: 99%

Drastic thickening of the barrier layer off the western coast of Sumatra due to the Madden-Julian oscillation passage during the Pre-Years of the Maritime Continent campaign

Moteki

Katsumata

Yoneyama

et al. 2018

Prog Earth Planet Sci

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The drastic thickening of the barrier layer in the marginal sea off the western coast of Sumatra during the passage of the Madden-Julian oscillation (MJO) observed during December 2015 is investigated. Before the MJO arrival, the halocline above a depth of 20 m was very strong, and the barrier layer thickness was 5-10 m based on R/V Mirai observations. During the MJO forcing of 13-16 December, the isothermal layer drastically deepened from 20 to 100 m. Meanwhile, the mixed layer deepening lagged behind the isothermal layer deepening by 1 day, and the barrier layer underwent dramatic thickening to 60 m within 24 h. An evaluation of the vertical salinity gradient tendency showed that the dramatic thickening of the barrier layer was due to the vertical oceanic mixing by the atmospheric MJO forcing and the vertical stretching by the oceanic downwelling coastal Kelvin wave intruding from the open ocean. In addition, an evaluation of the vertical temperature gradient tendency showed that the temperature inversion in the barrier layer formed by losing heat to the atmosphere due to the MJO forcing and downward advection of the temperature gradient due to the downwelling Kelvin wave resulting in the dramatic isothermal layer deepening. One of the important factors in the drastic barrier layer thickening was the atmospheric external forcing and the oceanic internal wave being in phase. The downwelling oceanic Kelvin wave continuously lowered the thermocline from the middle of November to the end of December, and the salinity stratification in the vicinity of the thermocline was continuously mitigated by the vertical stretching. Under such conditions, the MJO forcing caused vertical mixing of the freshwater with strong salinity stratification and temperature stratification near the surface. The combination of the two distinct processes caused the drastic thickening of the barrier layer, and the barrier layer thickness reached a maximum of 85 m 5 days after the MJO arrival.

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“…In this study, the ocean mixed‐layer depth (MLD) is estimated based on a variable density criterion proposed by Kara et al (), where the MLD is constructed using a density variability (Δσ) that is determined by the corresponding temperature change Δ T (0.8°C) (Vissa et al, ) using the UNESCO formulation of the equation of state. The following relation is used in the estimation of MLD

Δ σ = σ_{t *} true(T_{0} + Δ T, S_{0}, P_{0} true) - σ_{t} true(T_{0}, S_{0}, P_{0} true)

where

Δ σ

is the density difference from the surface to the base of the MLD;

σ_{t *}

is the density equal to the change in Δ T (±0.8°C accounts for the existence of thermal inversions) from the surface temperature ( T 0 ) while keeping the salinity constant;

σ_{t}

is the surface density (kg/m 3 ), and S 0 and P 0 are the surface salinity and pressure, respectively.…”

Section: Methodsmentioning

confidence: 99%

Seasonal and Interannual Variability in the Barrier Layer of the Bay of Bengal

2018

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An objectively analyzed monthly gridded ocean analysis derived from a combination of satellite and in situ observations is used to describe the seasonal and interannual variability in the barrier layer thickness (BLT) over the maximum variance region in the BLT of the Bay of Bengal (BoB) for the period from 1993 to 2012. The northern BoB acquires a maximum variance in the BLT where a large river discharge flux was observed. The BLT showed strong seasonal variability with minima during April–May and maxima during December–February. An investigation of the variability in the BLT showed large amplitude at annual and semiannual time scales. The relationship between the BLT and the Indian Ocean dipole mode (IOD) reveals that the BLT maximum is relatively high in the negative IOD years when compared to the positive IOD years. A significant relation between the BLT and IOD is inferred with the IOD leading the BLT by 3 months and lagging by 1 month. We show that the 1 month lag in the northern BoB is mainly associated with coastally trapped Kelvin waves that radiate Rossby waves and control the BLT. However, further investigation is required regarding the temporal lead of the IOD with the BLT in the northern BoB.

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Response of upper ocean and impact of barrier layer on Sidr cyclone induced sea surface cooling

Cited by 54 publications

References 37 publications

The response of ocean parameters to tropical cyclones in the Bay of Bengal

The response of ocean parameters to tropical cyclones in the Bay of Bengal

Drastic thickening of the barrier layer off the western coast of Sumatra due to the Madden-Julian oscillation passage during the Pre-Years of the Maritime Continent campaign

Seasonal and Interannual Variability in the Barrier Layer of the Bay of Bengal

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