The effect of upper ocean eddies on the non‐steric contribution to the barotropic mode

Shriver, Jay F.; Hurlburt, Harley E.

doi:10.1029/1999gl011105

Cited by 9 publications

(5 citation statements)

References 19 publications

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“…Several studies have combined altimetric and hydrographic observations to infer properties of the upper ocean [e.g., Carnes et al ., ; Goni et al ., ; Gilson et al ., ; Arnault and Kestenare , ; Phillips and Rintoul , ; Ridgway and Dunn , ], using the vertical coherence of the ocean as a basis for deriving such relationships. The skill of these synthetic methodologies varies among different regions of the ocean [ Guinehut et al ., ], since altimetry captures both steric and nonsteric components, and in some regions the nonsteric contributions, such as the barotropic component, can account for more than 50% of the total sea level variability [ Shriver and Hurlburt , ]. More recently developed synthetic methodologies use, for example, bottom pressure information to subtract the nonsteric component of the SLH, which is widely used in assimilation models [e.g., Shriver and Hurlburt , ; Barron et al ., ], empirical orthogonal functions to build depth‐dependent relationships throughout the water column [ Fox et al ., ], and a combination of altimetry, in situ and gravimetric data (e.g., GRACE) to study the sea level variability [ Willis et al ., ; Leuliette and Miller , ].…”

Section: Methodsmentioning

confidence: 99%

Variability of the Atlantic off‐equatorial eastward currents during 1993–2010 using a synthetic method

et al. 2013

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[1] We have developed, validated, and applied a synthetic method to monitor the offequatorial eastward currents in the central tropical Atlantic. This method combines highdensity expendable bathythermograph (XBT) temperature data along the AX08 transect with altimetric sea level anomalies (SLAs) to estimate dynamic height fields from which the mean properties of the North Equatorial Countercurrent (NECC), the North Equatorial Undercurrent (NEUC) and the South Equatorial Undercurrent (SEUC), and their variability can be estimated on seasonal to interannual timescales. On seasonal to interannual timescales, the synthetic method is well suited for reconstructions of the NECC variability, reproduces the variability of the NEUC with considerable skill, and less efficiently describes variations of the SEUC, which is located in a region of low SLA variability. A positive correlation is found between interannual variations of the NECC transport and two indices based on an interhemispheric sea surface temperature (SST) gradient and southeasterly wind stress in the central tropical Atlantic. The NEUC is correlated on interannual timescales with SSTs and meridional wind stress in the Gulf of Guinea and zonal equatorial wind stress. This study shows that both altimetry and XBT data can be effectively combined for near-real-time inference of the dynamic and thermodynamic properties of the tropical Atlantic current system.

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Section: Methodsmentioning

confidence: 99%

Variability of the Atlantic off‐equatorial eastward currents during 1993–2010 using a synthetic method

et al. 2013

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“…However, MODAS does not use the total NLOM SSH; MODAS expects the SSH it provided to be equivalent to an offset from the steric height anomaly relative to 1000 m in the MODAS hydrographic climatology [ Boebel and Barron , 2003]. In general, the SSH observed by altimeters or simulated in an ocean model is a combination of steric and nonsteric components; Shriver and Hurlburt [2000] find that the nonsteric component contributes over 50% of the total SSH variability for more than 37% of the global ocean. They also describe how the abyssal pressure anomaly can be used to determine SSHN, the nonsteric contribution to SSH.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of ocean models using observed and simulated drifter trajectories: Impact of sea surface height on synthetic profiles for data assimilation

Barron¹,

Smedstad²,

Dastugue³

et al. 2007

J. Geophys. Res.

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[1] The impact of global Navy Layered Ocean Model (NLOM) sea surface height (SSH) on global Navy Coastal Ocean Model (NCOM) nowcasts of ocean currents is investigated in a series of experiments. The studies focus on two primary aspects: the role of NLOM horizontal resolution and the role of differences between the SSH means in NLOM and the Modular Ocean Data Assimilation System (MODAS) climatology. To evaluate the impact of changes to the assimilation system, we compare observed drifter trajectories with trajectories simulated using global NCOM over 7-day timescales. The results indicate general improvement in NCOM currents as a result of increasing NLOM horizontal resolution. The effects of accounting for the differences between NLOM and MODAS mean that SSH is less clear, with some regions showing a decline in simulation skill while others show improvement or little impact. These outcomes supported recommendations for operational transition to 1/32°global NLOM with continued refinement to methods accounting for differences in mean SSH. (2007), Evaluation of ocean models using observed and simulated drifter trajectories: Impact of sea surface height on synthetic profiles for data assimilation,

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“…For instance, mesoscale eddies and western boundary currents dominate subtidal steric SSH variability [ Le Traon and Morrow , ]. Atmospheric pressure loading and winds contribute importantly to nonsteric SSH variance over a wide range of frequencies, from supertidal to annual and longer [ Ponte and Gaspar , ; Shriver and Hurlburt , ; Stammer et al ., ; Tierney et al ., ; Carrère and Lyard , ; Fu and Cazenave , ]. Diurnal and semidiurnal barotropic tides contribute importantly to nonsteric SSH [ Le Provost , ] and diurnal and semidiurnal internal tides contribute importantly to steric SSH variance [ Ray and Mitchum , ; Ray and Zaron , ; Shriver et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Frequency content of sea surface height variability from internal gravity waves to mesoscale eddies

et al. 2017

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High horizontal‐resolution ( 1/12.5° and 1/25°) 41‐layer global simulations of the HYbrid Coordinate Ocean Model (HYCOM), forced by both atmospheric fields and the astronomical tidal potential, are used to construct global maps of sea surface height (SSH) variability. The HYCOM output is separated into steric and nonsteric and into subtidal, diurnal, semidiurnal, and supertidal frequency bands. The model SSH output is compared to two data sets that offer some geographical coverage and that also cover a wide range of frequencies—a set of 351 tide gauges that measure full SSH and a set of 14 in situ vertical profilers from which steric SSH can be calculated. Three of the global maps are of interest in planning for the upcoming Surface Water and Ocean Topography (SWOT) two‐dimensional swath altimeter mission: (1) maps of the total and (2) nonstationary internal tidal signal (the latter calculated after removing the stationary internal tidal signal via harmonic analysis), with an average variance of 1.05 and 0.43 cm2, respectively, for the semidiurnal band, and (3) a map of the steric supertidal contributions, which are dominated by the internal gravity wave continuum, with an average variance of 0.15 cm2. Stationary internal tides (which are predictable), nonstationary internal tides (which will be harder to predict), and nontidal internal gravity waves (which will be very difficult to predict) may all be important sources of high‐frequency “noise” that could mask lower frequency phenomena in SSH measurements made by the SWOT mission.

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The effect of upper ocean eddies on the non‐steric contribution to the barotropic mode

Cited by 9 publications

References 19 publications

Variability of the Atlantic off‐equatorial eastward currents during 1993–2010 using a synthetic method

Variability of the Atlantic off‐equatorial eastward currents during 1993–2010 using a synthetic method

Evaluation of ocean models using observed and simulated drifter trajectories: Impact of sea surface height on synthetic profiles for data assimilation

Frequency content of sea surface height variability from internal gravity waves to mesoscale eddies

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