Effect of Mesoscale Oceanic Eddies on Extratropical Cyclogenesis: A Tracking Approach

Zhang, Xingzhi; Ma, Xiaoyan; Wu, Lixin

doi:10.1029/2019jd030595

Cited by 17 publications

(30 citation statements)

References 36 publications

(52 reference statements)

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“…However, considering the oceanic eddies are not isolated in real ocean, the combined anisotropic eddies can also influence the local SST gradient thereby exert forcing on MABL via baroclinicity. The above-mentioned discoveries of isolated single oceanic eddy within MABL are consistent with previous researches in other sea regions (Small et al, 2008;Ma et al, 2015a;Chen et al, 2017), yet oceanic eddies have broader influence on free atmosphere beyond MABL (Ma et al, 2015a;Zhang et al, 2019;Sun et al, 2020). Fig.…”

Section: Local Forcings Of the Complex Eddy Combinations To The Middle And Lower Atmospheresupporting

confidence: 90%

“…Cold (Warm) eddy causes surface winds to decelerate (accelerate) and reduces (increase) latent and sensible heat fluxes, cloud liquid water, water vapor content, and rain rate locally (Ma et al, 2015a). The influences of some steady isolated oceanic eddies are found even propagating to the top troposphere, causing variances of local convection and precipitation (Minobe et al, 2008;Ma et al, 2015a;Zhang et al, 2019;Sun et al, 2020). All these researches emphasize the local effects of an isolated steady eddy (cyclone or anticyclone).…”

Section: Introductionmentioning

confidence: 99%

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Local and remote forcing effects of oceanic eddies in the subtropical front zone on the mid-latitude atmosphere in Winter

Zhao

Zhang

et al. 2021

Clim Dyn

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remote forcing of eddies; atmospheric baroclinic waves; local forcing of eddies; MABL Key points: 1. Multiple oceanic eddies in the North Pacific STFZ exert remote and local forcings on winter mid-latitude atmosphere, which can be classified into the isolated single, the combined double isotropic and pairs of anisotropic eddies; 2. The spatial distribution of these multiple oceanic eddies in STFZ results in the remote forcing on upper troposphere by causing anomalies of basin-scale meridional SST gradient and atmospheric baroclinicity; 3. Three types of multiple oceanic eddies in STFZ have notably different local forcings on the middle and lower atmosphere in winter.

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Section: Local Forcings Of the Complex Eddy Combinations To The Middle And Lower Atmospheresupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Local and remote forcing effects of oceanic eddies in the subtropical front zone on the mid-latitude atmosphere in Winter

Zhao

Zhang

et al. 2021

Clim Dyn

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“…It is also becoming more evident that resolving mesoscale features can impact the synoptic weather band (X. Zhang et al, 2019). This points to a significant need to incorporate understanding of these air-sea feedback processes into mesoscale eddy subgrid parameterizations that will continue be required in coarse-resolution Earth system models for possibly decades to come.…”

Section: Journal Of Advances In Modeling Earth Systemsmentioning

confidence: 99%

The Global Sink of Available Potential Energy by Mesoscale Air‐Sea Interaction

Bishop

Small

Bryan

2020

J Adv Model Earth Syst

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The thermal component of oceanic eddy available potential energy (EPE) generation due to air-sea interaction is proportional to the product of anomalous sea surface temperature (SST) and net air-sea heat flux (SHF). In this study we assess EPE generation and its timescale and space-scale dependence from observations and a high-resolution coupled climate model. A dichotomy exists in the literature with respect to the sign of this term, that is, whether it is a source or a sink of EPE. We resolve this dichotomy by partitioning the SST and net heat flux into climatological mean, climatological seasonal cycle, and remaining transient contributions, thereby separating the mesoscale eddy variability from the forced seasonal cycle. In this decomposition the mesoscale air-sea SST-SHF feedbacks act as a 0.1 TW global sink of EPE. In regions of the ocean with a large seasonal cycle, for example, midlatitudes of the Northern Hemisphere, the EPE generation by the forced seasonal cycle exceeds the mesoscale variability sink, such that the global generation by seasonal plus eddy variability acts as a 0.8 TW source. EPE destruction is largest in the midlatitude western boundary currents due to mesoscale air-sea interaction and in the tropical Pacific where SST variability is due mainly to the El Niño-Southern Oscillation. The EPE sink in western boundary currents is spatially aligned with SST gradients and offset to the poleward side of currents, while the mean and seasonal generation are aligned with the warm core of the current. By successively smoothing the data in space and time we find that half of the EPE sink is confined to timescales less than annual and length scales less than 2 • , within the oceanic mesoscale band. Plain Language Summary In this study we find that anomalous air-sea interaction associated with ocean turbulence is responsible for removing potential energy from the global ocean circulation. This energy sink accounts for about 0.1 TW of energy that would otherwise be available for conversion from potential to kinetic energy of the anomalous flow field. It is found that the mean seasonal cycle is a source of potential energy and typically masks the sink associated with ocean turbulence. The sink of energy is locally confined to the strong midlatitude currents systems on the western side of ocean basins, such as the Gulf Stream in the North Atlantic and Kuroshio Extension in the North Pacific. The spatial locations of the sink point to possible future avenues for improving climate models by incorporating this sink, which is typically not resolved in standard climate models, and its subsequent impacts on the ocean circulation and future climate projections.

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“…Oceanic mesoscale eddies have been shown to play a decisive role in shaping the North Atlantic storm track as they support stronger storm growth rates, making their representation essential for a better description of the storm track (Ma et al, 2017;Zhang et al, 2019). In particular, Foussard et al (2019) examined the effect of oceanic eddies on storm tracks through an idealised experiment focused on the mid-latitudes, observing a poleward shift of storm trajectories compared to simulations in which mesoscale eddies are removed, as found by Ma et al (2017) in more realistic simulations for the North Pacific.…”

Section: Lorenz Energy Cycle and Flux-temperature Covariancementioning

confidence: 99%

The role of heat-flux–temperature covariance in the evolution of weather systems

Marcheggiani

Ambaum

2020

Weather Clim. Dynam.

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Abstract. Local diabatic heating and temperature anomaly fields need to be positively correlated for the diabatic heating to maintain a circulation against dissipation. Here we quantify the thermodynamic contribution of local air–sea heat exchange on the evolution of weather systems using an index of the spatial covariance between heat flux at the air–sea interface and air temperature at 850 hPa upstream of the North Atlantic storm track, corresponding with the Gulf Stream extension region. The index is found to be almost exclusively negative, indicating that the air–sea heat fluxes act locally as a sink on potential energy. It features bursts of high activity alternating with longer periods of lower activity. The characteristics of these high-index bursts are elucidated through composite analysis and the mechanisms are investigated in a phase space spanned by two different index components. It is found that the negative peaks in the index correspond with thermodynamic activity triggered by the passage of a weather system over a spatially variable sea-surface temperature field; our results indicate that most of this thermodynamically active heat exchange is realised within the cold sector of the weather systems.

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Effect of Mesoscale Oceanic Eddies on Extratropical Cyclogenesis: A Tracking Approach

Cited by 17 publications

References 36 publications

Local and remote forcing effects of oceanic eddies in the subtropical front zone on the mid-latitude atmosphere in Winter

Local and remote forcing effects of oceanic eddies in the subtropical front zone on the mid-latitude atmosphere in Winter

The Global Sink of Available Potential Energy by Mesoscale Air‐Sea Interaction

The role of heat-flux–temperature covariance in the evolution of weather systems

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