Transition regions and their role in the relationship between sea surface height and subsurface temperature structure in the Atlantic Ocean

2001 ◽  
Vol 28 (20) ◽  
pp. 3943-3946 ◽  
Author(s):  
Dennis A. Mayer ◽  
Robert L. Molinari ◽  
Molly O'Neil Baringer ◽  
Gustavo J. Goni
Keyword(s):  
Atlantic Ocean ◽  
Sea Surface Height ◽  
Sea Surface ◽  
Temperature Structure ◽  
Subsurface Temperature ◽  
The Relationship

scholarly journals On the Relationship between Regional Ocean Heat Content and Sea Surface Height

2017 ◽  
Vol 30 (22) ◽  
pp. 9195-9211 ◽  
Author(s):  
John T. Fasullo ◽  
Peter R. Gent
Keyword(s):  
Time Scales ◽  
Low Frequency ◽  
Heat Content ◽  
Sea Surface Height ◽  
Ocean Heat Content ◽  
Ocean Dynamics ◽  
Sea Surface ◽  
Altimeter Data ◽  
Model Control ◽  
The Relationship

Abstract An accurate diagnosis of ocean heat content (OHC) is essential for interpreting climate variability and change, as evidenced for example by the broad range of hypotheses that exists for explaining the recent hiatus in global mean surface warming. Potential insights are explored here by examining relationships between OHC and sea surface height (SSH) in observations and two recently available large ensembles of climate model simulations from the mid-twentieth century to 2100. It is found that in decadal-length observations and a model control simulation with constant forcing, strong ties between OHC and SSH exist, with little temporal or spatial complexity. Agreement is particularly strong on monthly to interannual time scales. In contrast, in forced transient warming simulations, important dependencies in the relationship exist as a function of region and time scale. Near Antarctica, low-frequency SSH variability is driven mainly by changes in the circumpolar current associated with intensified surface winds, leading to correlations between OHC and SSH that are weak and sometimes negative. In subtropical regions, and near other coastal boundaries, negative correlations are also evident on long time scales and are associated with the accumulated effects of changes in the water cycle and ocean dynamics that underlie complexity in the OHC relationship to SSH. Low-frequency variability in observations is found to exhibit similar negative correlations. Combined with altimeter data, these results provide evidence that SSH increases in the Indian and western Pacific Oceans during the hiatus are suggestive of substantial OHC increases. Methods for developing the applicability of altimetry as a constraint on OHC more generally are also discussed.

Contributions of Wind Forcing and Surface Heating to Interannual Sea Level Variations in the Atlantic Ocean

2006 ◽  
Vol 36 (9) ◽  
pp. 1739-1750 ◽  
Author(s):  
Cécile Cabanes ◽  
Thierry Huck ◽  
Alain Colin de Verdière
Keyword(s):  
Atlantic Ocean ◽  
Sea Level ◽  
Wind Stress ◽  
Large Scale ◽  
Sea Surface Height ◽  
Sea Surface ◽  
Altimeter Data ◽  
Local Response ◽  
Sea Level Variability ◽  
Sea Level Variations

Abstract Interannual sea surface height variations in the Atlantic Ocean are examined from 10 years of high-precision altimeter data in light of simple mechanisms that describe the ocean response to atmospheric forcing: 1) local steric changes due to surface buoyancy forcing and a local response to wind stress via Ekman pumping and 2) baroclinic and barotropic oceanic adjustment via propagating Rossby waves and quasi-steady Sverdrup balance, respectively. The relevance of these simple mechanisms in explaining interannual sea level variability in the whole Atlantic Ocean is investigated. It is shown that, in various regions, a large part of the interannual sea level variability is related to local response to heat flux changes (more than 50% in the eastern North Atlantic). Except in a few places, a local response to wind stress forcing is less successful in explaining sea surface height observations. In this case, it is necessary to consider large-scale oceanic adjustments: the first baroclinic mode forced by wind stress explains about 70% of interannual sea level variations in the latitude band 18°–20°N. A quasi-steady barotropic Sverdrup response is observed between 40° and 50°N.

scholarly journals Investigating the relationship between volume transport and sea surface height in a numerical ocean model

2018 ◽  
Author(s):  
Estee Vermeulen ◽  
Björn Backeberg ◽  
Juliet Hermes ◽  
Shane Elipot
Keyword(s):  
Sea Surface Height ◽  
Volume Transport ◽  
Ocean Model ◽  
Sea Surface ◽  
Linear Regression Models ◽  
Current Time ◽  
Agulhas Current ◽  
Modelling Framework ◽  
Long Time ◽  
The Relationship

Abstract. The Agulhas Current Time-series mooring array (ACT) measured transport of the Agulhas Current at 34° S for a period of 3 years. Using along-track satellite altimetry data directly above the array, a proxy of Agulhas Current transport was developed based on the relationship between cross-current sea surface height (SSH) gradients and the measured transports. In this study, the robustness of the proxy is tested within a numerical modelling framework, using a 34-year long regional-hindcast simulation from the Hybrid Coordinate Ocean Model (HYCOM). Two reference proxies were created using HYCOM data from 2010–2013, extracting model data at the mooring positions and along the satellite altimeter track for; (1) the box transport (Tbox) and (2) the jet (southwestward) transport (Tjet). Next, sensitivity tests were performed where the proxy was recalculated from HYCOM for (1) a period where the modelled vertical stratification was different compared to the reference proxy, and (2) different lengths of periods: 1, 3, 6, 12, 18 and 34 years. Compared to the simulated (native) transports, it was found that the HYCOM proxy was more capable of estimating the box transport of the Agulhas Current compared to the jet transport. The HYCOM configuration in this study contained exaggerated levels of offshore variability in the form of frequently-impinging baroclinic anticyclonic eddies. These eddies consequently broke down the linear relationship between SSH slope and vertically-integrated transport, resulting in stronger correlations for the inshore linear regression models compared to the ones offshore. Vertically-integrated transport estimates were therefore more accurate inshore than those offshore or when the current was in a meandering state. Results showed that calculating the proxy over shorter or longer time periods in the model did not significantly impact the skill of the Agulhas transport proxy, suggesting that 3-years was a sufficiently long time-period for the observation based transport proxy.

scholarly journals Study Of Albacore Tuna (Thunnus alalunga) Abundance Using Regional Ocean Modeling System (ROMS) Data In Indian Ocean

2018 ◽  
Vol 2 (2) ◽  
pp. 76
Author(s):  
Dian Novianto ◽  
Takahiro Osawa ◽  
I Wayan Nuarsa
Keyword(s):  
Current Velocity ◽  
Sea Surface Height ◽  
Environmental Variable ◽  
Ocean Modeling ◽  
Sea Surface ◽  
Regional Ocean Modeling System ◽  
Catch Data ◽  
Albacore Tuna ◽  
Thunnus Alalunga ◽  
The Relationship

First, we analysed alabcore catch data based on time, positions, and layer alabcore caught and ROMS result data monthly climatology data for temperature, salinity. current velocity, and sea surface height for 2005–2008. Then, we analyzed the relationship between catch data and ROMS data by combining the statistical method of regression trogh origin (RTO)  and geographic information system (GIS). Three model RTO were generated with the abundance of albacore tuna as a response variable, and  temperature, salinity. current velocity, and sea surface height as predictor variables. All of the predictors of  temperature, salinity. current velocity, and sea surface height were highly significant (P < 0.001) to the number of albacore tuna. Values of temperature, salinity. current velocity, and sea surface height in albacore tuna preferences ranged from 220 to 230 C, 34.79 to 34.84 Psu, 0.01 to 0.03 m/s and 0.66 to 0.70 m, respectively. Validation of the predicted number ofalbacore tuna with the observed value was significant (P < 0.05, r2 = 0.60). sea surface height was the most important environmental variable to the number of albacore tuna caught, followed by temperature, salinity and current velocity.

scholarly journals Investigating the relationship between volume transport and sea surface height in a numerical ocean model

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 513-526
Author(s):  
Estee Ann Vermeulen ◽  
Björn Backeberg ◽  
Juliet Hermes ◽  
Shane Elipot
Keyword(s):  
Sea Surface Height ◽  
Volume Transport ◽  
Ocean Model ◽  
Sea Surface ◽  
Current Time ◽  
Agulhas Current ◽  
Modelling Framework ◽  
Modelling Studies ◽  
Time Periods ◽  
The Relationship

Abstract. The Agulhas Current Time-series Experiment mooring array (ACT) measured transport of the Agulhas Current at 34∘ S for a period of 3 years. Using along-track satellite altimetry data directly above the array, a proxy of Agulhas Current transport was developed based on the relationship between cross-current sea surface height (SSH) gradients and the measured transports. In this study, the robustness of the proxy is tested within a numerical modelling framework using a 34-year-long regional hindcast simulation from the Hybrid Coordinate Ocean Model (HYCOM). The model specifically tested the sensitivity of the transport proxy to (1) changes in the vertical structure of the current and to (2) different sampling periods used to calculate the proxy. Two reference proxies were created using HYCOM data from 2010 to 2013 by extracting model data at the mooring positions and along the satellite altimeter track for the box (net) transport and the jet (southwestward) transport. Sensitivity tests were performed where the proxy was recalculated from HYCOM for (1) a period where the modelled vertical stratification was different compared to the reference proxy and (2) different lengths of time periods: 1, 3, 6, 12, 18, and 34 years. Compared to the simulated (native) transports, it was found that the HYCOM proxy was more capable of estimating the box transport of the Agulhas Current compared to the jet transport. This was because the model is unable to resolve the dynamics associated with meander events, for which the jet transport algorithm was developed. The HYCOM configuration in this study contained exaggerated levels of offshore variability in the form of frequently impinging baroclinic anticyclonic eddies. These eddies consequently broke down the linear relationship between SSH slope and vertically integrated transport. Lastly, results showed that calculating the proxy over shorter or longer time periods in the model did not significantly impact the skill of the Agulhas transport proxy. Modelling studies of this kind provide useful information towards advancing our understanding of the sensitivities and limitations of transport proxies that are needed to improve long-term ocean monitoring approaches.

scholarly journals Seasonal sea surface height variability in the North Atlantic Ocean

2000 ◽  
Vol 105 (C3) ◽  
pp. 6307-6326 ◽  
Author(s):  
Nicolas Ferry ◽  
Gilles Reverdin ◽  
Andreas Oschlies
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Sea Surface Height ◽  
Sea Surface ◽  
The North ◽  
The North Atlantic
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