Numerical investigation of an oceanic resonant regime induced by hurricane winds

Samson, Guillaume; Giordani, Hervé; Caniaux, Guy; Roux, Frank

doi:10.1007/s10236-009-0203-8

Cited by 31 publications

(31 citation statements)

References 34 publications

(75 reference statements)

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“…Note that we chose not to take into account the translation speed of the storm in the wind vortex we added. Indeed, even if it is known to affect the wind asymmetry, Samson et al [2009] have shown that it has a limited effect on the CW asymmetry and can be neglected. The validity of our methodology for simulating the ocean response to TCs will be further illustrated in the next section.…”

Section: Data Sets and Methodsmentioning

confidence: 99%

Processes setting the characteristics of sea surface cooling induced by tropical cyclones

Vincent¹,

Lengaigne²,

Madec³

et al. 2012

J. Geophys. Res.

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[1] A 1/2°resolution global ocean general circulation model is used to investigate the processes controlling sea surface cooling in the wake of tropical cyclones (TCs). Wind forcing related to more than 3000 TCs occurring during the 1978-2007 period is blended with the CORE II interannual forcing, using an idealized TC wind pattern with observed magnitude and track. The amplitude and spatial characteristics of the TC-induced cooling are consistent with satellite observations, with an average cooling of $1°C that typically extends over 5 radii of maximum wind. A Wind power index (WPi) is used to discriminate cooling processes under TCs with high-energy transfer to the upper ocean (strong and/or slow cyclones) from the others (weak and/or fast cyclones). Surface heat fluxes contribute to $50 to 80% of the cooling for weak WPi as well as away from the cyclone track. Within 200 km of the track, mixing-induced cooling increases linearly with WPi, explaining $30% of the cooling for weak WPis and up to $80% for large ones. Mixing-induced cooling is strongly modulated by pre-storm oceanic conditions. For a given WPi, vertical processes can induce up to 8 times more cooling for shallow mixed layer and steep temperature stratification than for a deep mixed layer. Vertical mixing is the main source of rightward bias of the cold wake for weak and moderate WPi, but along-track advection becomes the main contributor to the asymmetry for the largest WPis.

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Section: Data Sets and Methodsmentioning

confidence: 99%

Processes setting the characteristics of sea surface cooling induced by tropical cyclones

Vincent¹,

Lengaigne²,

Madec³

et al. 2012

J. Geophys. Res.

Self Cite

148

197

View full text Add to dashboard Cite

show abstract

“…In this scheme, the WEF and TKE can be viewed as transfer functions of energy across the air‐sea and thermocline interfaces, respectively. A similar process of mixed‐layer cooling has been pointed out for hurricane conditions where strong upwelling and WEF ‐induced TKE , combined with a sharp temperature gradient in the thermocline, lead to strong turbulent mixing at the mixed‐layer base [ Samson et al ., ].…”

Section: Mixed‐layer Heat Budgetmentioning

confidence: 99%

Intraseasonal mixed‐layer heat budget in the equatorial Atlantic during the cold tongue development in 2006

2013

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Estimating the mixed‐layer heat budget is a key issue for understanding the cold tongue development in the eastern equatorial Atlantic. A high‐resolution ocean regional model is used to diagnose the mixed‐layer heat budget online during the EGEE‐3 experiment from May to August 2006. The heat budget shows the major role of the horizontal advection and turbulent mixing in the mixed‐layer temperature balance in the cold tongue. The surface net heat flux and entrainment processes play a minor role. The equatorial cooling is mainly induced by low‐frequency advection, which is balanced by high‐frequency zonal and meridional advections. The high‐frequency advections are organized in patterns along the northern edge of the cold tongue, where they are associated with strong sea surface temperature gradients and well‐developed tropical instability waves in the western Atlantic. Special attention is paid to the wind energy flux, which controls horizontal advection and turbulent mixing. We suggest that the wind energy flux drives the vertical velocity, which in turn adjusts the mixed‐layer depth, its stratification, and the vertical shear of the horizontal current. Although vertical advection is not essential in providing cold water in the Atlantic cold tongue, it is shown that the vertical velocity plays a central role in preconditioning the mixed layer and maximizes the turbulent mixing.

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“…This vertical mixing largely results from the intense vertical shear related to the strong inertial currents driven by TCs (Price 1983;Greatbatch 1984;D'Asaro 1985;Shay et al 1989;Price et al 1994;D'Asaro et al 1995;Crawford and Large 1996;Tsai et al 2008;Samson et al 2009;Jullien et al 2012). Recently, Vincent et al (2012a) have confirmed that vertical mixing is the dominant cooling process close to cyclone tracks and for strong cyclones by using an ocean general circulation model to study the cold wake of more than 3000 TCs over the last 30 years.…”

Section: Introductionmentioning

confidence: 97%

Observation-Based Estimates of Surface Cooling Inhibition by Heavy Rainfall under Tropical Cyclones

Jourdain

Lengaigne

Vialard

et al. 2013

Journal of Physical Oceanography

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Tropical cyclones drive intense ocean vertical mixing that explains most of the surface cooling observed in their wake (the ''cold wake''). In this paper, the authors investigate the influence of cyclonic rainfall on the cold wake at a global scale over the 2002-09 period. For each cyclone, the cold wake intensity and accumulated rainfall are obtained from satellite data and precyclone oceanic stratification from the Global EddyPermitting Ocean Reanalysis (GLORYS2). The impact of precipitation on the cold wake is estimated by assuming that cooling is entirely due to vertical mixing and that an extra amount of energy (corresponding to the energy used to mix the rain layer into the ocean) would be available for mixing the ocean column in the hypothetical case with no rain. The positive buoyancy flux of rainfall reduces the mixed layer depth after the cyclone passage, hence reducing cold water entrainment. The resulting reduction in cold wake amplitude is generally small (median of 0.07 K for a median 1 K cold wake) but not negligible (.19% for 10% of the cases). Despite similar cyclonic rainfall, the effect of rain on the cold wake is strongest in the Arabian Sea and weak in the Bay of Bengal. An analytical approach with a linearly stratified ocean allows attributing this difference to the presence of barrier layers in the Bay of Bengal. The authors also show that the cold wake is generally a ''salty wake'' because entrainment of subsurface saltier water overwhelms the dilution effect of rainfall. Finally, rainfall temperature has a negligible influence on the cold wake.

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Numerical investigation of an oceanic resonant regime induced by hurricane winds

Cited by 31 publications

References 34 publications

Processes setting the characteristics of sea surface cooling induced by tropical cyclones

Processes setting the characteristics of sea surface cooling induced by tropical cyclones

Intraseasonal mixed‐layer heat budget in the equatorial Atlantic during the cold tongue development in 2006

Observation-Based Estimates of Surface Cooling Inhibition by Heavy Rainfall under Tropical Cyclones

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