Satellite‐based midlatitude cyclone statistics over the Southern Ocean: 1. Scatterometer‐derived pressure fields and storm tracking

Patoux, Jérôme; Yuan, Xiaojun; Li, Cuihua

doi:10.1029/2008jd010873

Cited by 35 publications

(32 citation statements)

References 72 publications

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“…τ max is modulated by a sinusoidal seasonal cycle so it varies from τ max0 /2 during austral summer and τ max0 during austral winter, with τ max0 = 1.5 N m −2 . Each vortex forms and vanishes at the same latitude (no meridional displacement) but the latitude of formation varies following a Gamma distribution similar to the meridional distribution inferred from cyclones tracks in Patoux et al (2009), with most of the cyclones located between 50 and 70 • S. The distribution follows a cycle that repeats each 10 years. The lifetime of the storms is computed such that one cyclone travels the 2000 km zonal extension of the domain with full strength (∼ 2 days).…”

Section: Appendix A: Wind Forcing Strategymentioning

confidence: 99%

“…These high-frequency winds induce intense near-inertial energy and mixing into the ocean interior. From the analysis of scatterometer measurements, Patoux et al (2009) provided general statistics of the spatial and temporal variability of the Southern Ocean midlatitude cyclones for the period 1999-2006: most of the cyclones occurred between 50 and 70 • S, have a radius between 400 and 800 km and last between 12 h and 5 days. Mesoscale cyclones lasting less than 4 days represent about 75 % of all cyclone tracks ).…”

Section: Modelmentioning

confidence: 99%

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Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean

et al. 2016

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Abstract. The aim of this study is to clarify the role of the Southern Ocean storms on interior mixing and meridional overturning circulation. A periodic and idealized numerical model has been designed to represent the key physical processes of a zonal portion of the Southern Ocean located between 70 and 40 • S. It incorporates physical ingredients deemed essential for Southern Ocean functioning: rough topography, seasonally varying air-sea fluxes, and highlatitude storms with analytical form. The forcing strategy ensures that the time mean wind stress is the same between the different simulations, so the effect of the storms on the mean wind stress and resulting impacts on the Southern Ocean dynamics are not considered in this study. Level and distribution of mixing attributable to high-frequency winds are quantified and compared to those generated by eddy-topography interactions and dissipation of the balanced flow. Results suggest that (1) the synoptic atmospheric variability alone can generate the levels of mid-depth dissipation frequently observed in the Southern Ocean (10 −10 -10 −9 W kg −1 ) and (2) the storms strengthen the overturning, primarily through enhanced mixing in the upper 300 m, whereas deeper mixing has a minor effect. The sensitivity of the results to horizontal resolution (20, 5, 2 and 1 km), vertical resolution and numerical choices is evaluated. Challenging issues concerning how numerical models are able to represent interior mixing forced by high-frequency winds are exposed and discussed, particularly in the context of the overturning circulation. Overall, submesoscale-permitting ocean modeling exhibits important delicacies owing to a lack of convergence of key components of its energetics even when reaching x = 1 km.

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Section: Appendix A: Wind Forcing Strategymentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean

et al. 2016

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“…These studies have focused on particular localized scenarios, and their relevance has not yet been contextualized within the broader seasonal mean state. The SO, in particular the SAZ, is a region of strong eddy (Frenger et al, ) and small‐scale frontal activity (du Plessis et al, , ) and strong winds from passing storms (Patoux et al, ; Yuan, ; Yuan et al, ). We hypothesize that storms increase mixing and advection during summer that are enhanced by wind‐mesoscale interactions and may result in nonnegligible physical iron supplies from the subsurface to the surface ocean to support phytoplankton production beyond what is possible by the once‐off winter supply.…”

Section: Introductionmentioning

confidence: 99%

Iron Supply Pathways Between the Surface and Subsurface Waters of the Southern Ocean: From Winter Entrainment to Summer Storms

Nicholson¹,

Lévy

Jouanno

et al. 2019

Geophysical Research Letters

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Dissolved iron (DFe) plays an immeasurable role in shaping the biogeochemical processes of the open-ocean Southern Ocean. However, due to observational constraints iron supply pathways remain poorly understood. Using an idealized eddy-resolving physical-biogeochemical model representing a turbulent sector of the Southern Ocean with seasonal buoyancy forcing and zonal winds overlaid by storms, we quantify the importance of a range of subsurface and surface iron supply mechanisms. The main physical supply pathways to the surface layer are via eddy advection and winter convective mixing in equal proportions. The associated subsurface loss of DFe is restocked via net remineralization (75%) and eddy advection (25%). Summer storms resulted in weak DFe supplies relative to the seasonal supplies (<7.6%). However, in situations of deep summer mixed layers and when interacting with underlying ocean fronts, summer storms resulted in enhanced diffusive and advective DFe supplies and raised summer primary production by 20% for several days. Plain Language SummaryThe surface of the Southern Ocean is iron depleted, which strongly limits the amount of phytoplankton growth that can occur. Every year, deep mixing in winter moves large quantities of iron from a subsurface underutilized iron reservoir to the surface alleviating the iron limitation. Once there is sufficient light in spring, phytoplankton consume this iron supply leaving the summer months iron depleted. How exactly phytoplankton are supported through the summer when iron limitations are strong remains under question. This study uses a numerical model to simulate the seasonal and intraseasonal iron supply pathways. We show that physical supplies via advection by eddies and winter mixing drive surface seasonal supplies in equal proportions. During summer, storms supply iron via intermittent mixing and thus increase primary production, particularly over regions of strong ocean fronts.

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“… Patoux et al [2009] (hereafter PYL) described how to use SLP fields derived from QuikSCAT (QS) scatterometer winds using the University of Washington planetary boundary layer (UWPBL) model [ Brown and Levy , 1986; Brown and Liu , 1982; Brown and Zeng , 1994; Patoux , 2004] to incorporate mesoscale to synoptic‐scale satellite information into NWP model surface analyses. The high‐wavenumber wavelet coefficients of the scatterometer‐derived pressure fields were injected into ECMWF SLP analyses over the Southern Ocean with the following method: (1) Swaths of surface pressure were retrieved from QS winds using the UWPBL model.…”

Section: Introductionmentioning

confidence: 99%

Satellite‐based midlatitude cyclone statistics over the Southern Ocean: 2. Tracks and surface fluxes

Yuan¹,

Patoux²,

Li³

2009

J. Geophys. Res.

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[1] Midlatitude cyclone tracks over the Southern Ocean are constructed for the 1999-2006 period using two surface data sets: European Centre for Medium-range Weather Forecasts (ECMWF) sea-level pressure analyses on one hand, and on the other hand modified analyses in which high-wavenumber pressure variability derived from scatterometer swaths has been injected with a wavelet-based method. A comparison of track statistics reveals the differences between the two data sets. The fluxes of momentum and sensible and latent heat associated with these midlatitude cyclones are calculated and sorted by life span. Three aspects of these cyclone flux statistics are investigated. (1) The momentum flux into the ocean is stronger inside cyclones than over the rest of the Southern Ocean, while the ocean loses more sensible and latent heat outside of the cyclones. (2) The momentum flux into the ocean and the loss of sensible and latent heat by the ocean are larger when calculated from the scatterometer-modified analyses than when calculated from the original ECMWF analyses. (3) Mesoscale cyclones (short-lived cyclones) contribute a significant amount of the fluxes between the atmosphere and the Southern Ocean, although over slightly different geographic areas from longer-lived cyclones.

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Satellite‐based midlatitude cyclone statistics over the Southern Ocean: 1. Scatterometer‐derived pressure fields and storm tracking

Cited by 35 publications

References 72 publications

Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean

Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean

Iron Supply Pathways Between the Surface and Subsurface Waters of the Southern Ocean: From Winter Entrainment to Summer Storms

Satellite‐based midlatitude cyclone statistics over the Southern Ocean: 2. Tracks and surface fluxes

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