scholarly journals An estimate of the Sunda Shelf and the Strait of Malacca transports: a numerical study

2015 ◽  
Vol 12 (1) ◽  
pp. 275-313 ◽  
Author(s):  
F. Daryabor ◽  
A. A. Samah ◽  
S. H. Ooi ◽  
S. N. Chenoli
Keyword(s):  
Numerical Study ◽  
Ocean Modeling ◽  
Sea Surface Salinity ◽  
Andaman Sea ◽  
Regional Ocean Modeling System ◽  
Sunda Shelf ◽  
Surface Salinity ◽  
Volume Heat ◽  
Ocean Data Assimilation ◽  
Strait Of Malacca

Abstract. Using the Regional Ocean Modeling System (ROMS), this study aims to provide an estimate of the volume, freshwater, heat, and salt transports through the Sunda Shelf and the Strait of Malacca in the southern region of the South China Sea (SSCS). The modeling system is configured with two one-way nested domains representing parent and child with resolutions of 1/2 and 1/12°, respectively. The simulated currents, sea surface salinity, temperature and various transports (e.g., volume, heat, etc) agree well with the observed values as well as those estimated from the Simple Ocean Data Assimilation (SODA) re-analysis product. The ROMS estimated seasonal and mean annual transports are in accord with those calculated from SODA and those of limited observations. The ROMS estimates of mean annual volume, freshwater, heat and salt transports through the Sunda Shelf into the Java Sea are 0.32Sv (1 Sv = 106 m3 s−1), 0.023 Sv, 0.032 PW (1 PW = 1015 j s−1), and 0.010 × 109 kg s−1 respectively. The corresponding ROMS estimates for mean annual transports through the Strait of Malacca into Andaman Sea are 0.14, 0.009 Sv, 0.014 PW, and 0.0043 × 109 kg s−1 respectively. The relative percentages of mean annual transports computed individually from those of volume, heat, salinity, and freshwater between the Strait of Malacca and the Sunda Shelf range from 39 to 43.8%. This reflects that the Strait of Malacca plays an equally significant role in the annual transports from the SSCS into the Andaman Sea.

scholarly journals Spatial Scales of Sea Surface Salinity Subfootprint Variability in the SPURS Regions

2020 ◽  
Vol 12 (23) ◽  
pp. 3996
Author(s):  
Frederick M. Bingham ◽  
Zhijin Li
Keyword(s):  
North Atlantic ◽  
Spatial Scales ◽  
Remote Sensing Data ◽  
Ocean Modeling ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Regional Ocean Modeling System ◽  
Surface Salinity ◽  
In Situ Data

Subfootprint variability (SFV), or representativeness error, is variability within the footprint of a satellite that can impact validation by comparison of in situ and remote sensing data. This study seeks to determine the size of the sea surface salinity (SSS) SFV as a function of footprint size in two regions that were heavily sampled with in situ data. The Salinity Processes in the Upper-ocean Regional Studies-1 (SPURS-1) experiment was conducted in the subtropical North Atlantic in the period 2012–2013, whereas the SPURS-2 study was conducted in the tropical eastern North Pacific in the period 2016–2017. SSS SFV was also computed using a high-resolution regional model based on the Regional Ocean Modeling System (ROMS). We computed SFV at footprint sizes ranging from 20 to 100 km for both regions. SFV is strongly seasonal, but for different reasons in the two regions. In the SPURS-1 region, the meso- and submesoscale variability seemed to control the size of the SFV. In the SPURS-2 region, the SFV is much larger than SPURS-1 and controlled by patchy rainfall.

scholarly journals Intercomparison of Global Sea Surface Salinity from Multiple Datasets over 2011–2018

2021 ◽  
Vol 13 (4) ◽  
pp. 811
Author(s):  
Hao Liu ◽  
Zexun Wei
Keyword(s):  
Time Scales ◽  
Correlation Coefficients ◽  
Dominant Mode ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Ocean Data Assimilation ◽  
Multiple Datasets ◽  
Different Time Scales

The variability in sea surface salinity (SSS) on different time scales plays an important role in associated oceanic or climate processes. In this study, we compare the SSS on sub-annual, annual, and interannual time scales among ten datasets, including in situ-based and satellite-based SSS products over 2011–2018. Furthermore, the dominant mode on different time scales is compared using the empirical orthogonal function (EOF). Our results show that the largest spread of ten products occurs on the sub-annual time scale. High correlation coefficients (0.6~0.95) are found in the global mean annual and interannual SSSs between individual products and the ensemble mean. Furthermore, this study shows good agreement among the ten datasets in representing the dominant mode of SSS on the annual and interannual time scales. This analysis provides information on the consistency and discrepancy of datasets to guide future use, such as improvements to ocean data assimilation and the quality of satellite-based data.

scholarly journals Small-Scale Variability in Sea Surface Salinity and Implications for Satellite-Derived Measurements

2013 ◽  
Vol 30 (11) ◽  
pp. 2689-2694 ◽  
Author(s):  
Nadya T. Vinogradova ◽  
Rui M. Ponte
Keyword(s):  
Sampling Error ◽  
In Situ Measurements ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Small Scale ◽  
Surface Salinity ◽  
Ocean Data Assimilation ◽  
Ocean Salinity ◽  
Mean Square Difference

Abstract Calibration and validation efforts of the Aquarius and Soil Moisture and Ocean Salinity (SMOS) satellite missions involve comparisons of satellite and in situ measurements of sea surface salinity (SSS). Such estimates of SSS can differ by the presence of small-scale variability, which can affect the in situ point measurement, but be averaged out in the satellite retrievals because of their large footprint. This study quantifies how much of a difference is expected between in situ and satellite SSS measurements on the basis of their different sampling of spatial variability. Maps of sampling error resulting from small-scale noise, defined here as the root-mean-square difference between “local” and footprint-averaged SSS estimates, are derived using a solution from a global high-resolution ocean data assimilation system. The errors are mostly <0.1 psu (global median is 0.05 psu), but they can be >0.2 psu in several regions, particularly near strong currents and outflows of major rivers. To examine small-scale noise in the context of other errors, its values are compared with the overall expected differences between monthly Aquarius SSS and Argo-based estimates. Results indicate that in several ocean regions, small-scale variability can be an important source of sampling error for the in situ measurements.

The impact of ocean data assimilation on the simulation of mesoscale eddies at São Paulo plateau (Brazil) using the regional ocean modeling system

2021 ◽  
pp. 101889
Author(s):  
Thiago Pires de Paula ◽  
Jose Antonio Moreira Lima ◽  
Clemente Augusto Souza Tanajura ◽  
Marcelo Andrioni ◽  
Renato Parkinson Martins ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Mesoscale Eddies ◽  
Sao Paulo ◽  
Ocean Modeling ◽  
São Paulo ◽  
Regional Ocean Modeling System ◽  
Ocean Data Assimilation ◽  
The Impact

scholarly journals Enhancement of Alongshore Freshwater Transport in Surface-Advected River Plumes by Tides

2014 ◽  
Vol 44 (11) ◽  
pp. 2951-2971 ◽  
Author(s):  
Shih-Nan Chen
Keyword(s):  
Numerical Study ◽  
Incident Angle ◽  
Ocean Modeling ◽  
Positive Pressure ◽  
Coastal Current ◽  
Current Transport ◽  
Coastal Currents ◽  
Regional Ocean Modeling System ◽  
Tidal Forcing ◽  
Freshwater Transport

Abstract A recent numerical study by Isobe showed that imposing alongshore tidal forcing on buoyant coastal discharge enhances the net freshwater transport in the coastal currents. The mechanisms for this transport enhancement are studied using a three-dimensional, primitive equation ocean model [Regional Ocean Modeling System (ROMS)]. Lagrangian drifters are used to trace the freshwater transport paths. It is found that the river plume bulge circulation largely follows the rigid-body motion (i.e., constant vorticity). The buoyant fluid near the bulge’s outer edge is thinner and faster, behaving as a baroclinic jet. The bulge currents then split after impinging on the coast. The outer fluid feeds the downshelf-flowing coastal currents, while the inner fluid recirculates to form the bulge. The coastal current transport estimated from the present and prior studies corresponds well to a baroclinic jet theory, with the incident angle of bulge currents at the coast being a key parameter. Without tides, the bulge is approximately circular. The incident angle measured with respect to the cross-shore axis is small. With tides, the convergence of tidal momentum fluxes near the upshelf plume front leads to a positive pressure anomaly, which acts to compress the bulge shoreward. As a result, the incident angle increases, which in turn enhances the downshelf momentum input, thus increasing the freshwater transport in the coastal currents. Finally, the parameter space for coastal current transport in the presence of tidal forcing is explored with a conceptual model. A few observational examples are given.

Seasonal Variability of Salinity and Salt Transport in the Northern Indian Ocean

2015 ◽  
Vol 45 (7) ◽  
pp. 1947-1966 ◽  
Author(s):  
Joseph M. D’Addezio ◽  
Bulusu Subrahmanyam ◽  
Ebenezer S. Nyadjro ◽  
V. S. N. Murty
Keyword(s):  
Indian Ocean ◽  
Seasonal Variability ◽  
Ocean Model ◽  
Salt Transport ◽  
Sea Surface Salinity ◽  
Northern Indian Ocean ◽  
Surface Salinity ◽  
Ocean Reanalysis ◽  
Model Simulations ◽  
Ocean Data Assimilation

AbstractAnalyses using a suite of observational datasets (Aquarius and Argo) and model simulations are carried out to examine the seasonal variability of salinity in the northern Indian Ocean (NIO). The model simulations include Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2), the European Centre for Medium-Range Weather Forecasts–Ocean Reanalysis System 4 (ECMWF–ORAS4), Simple Ocean Data Assimilation (SODA) reanalysis, and the Hybrid Coordinate Ocean Model (HYCOM). The analyses of salinity at the surface and at depths up to 200 m, surface salt transport in the top 5-m layer, and depth-integrated salt transports revealed different salinity processes in the NIO that are dominantly related to the semiannual monsoons. Aquarius proves a useful tool for observing this dynamic region and reveals some aspects of sea surface salinity (SSS) variability that Argo cannot resolve. The study revealed large disagreement between surface salt transports derived from observed- and analysis-derived salinity fields. Although differences in SSS between the observations and the model solutions are small, model simulations provide much greater spatial variability of surface salt transports due to finer detailed current structure. Meridional depth-integrated salt transports along 6°N revealed dominant advective processes from the surface toward near-bottom depths. In the Arabian Sea (Bay of Bengal), the net monthly mean maximum northward (southward) salt transport of ~50 × 106 kg s −1 occurs in July, and annual-mean salt transports across this section are about −2.5 × 106 kg s −1 (3 × 106 kg s −1).

scholarly journals Corrigendum to “The impact of ocean data assimilation on the simulation of mesoscale eddies at São Paulo plateau (Brazil) using the regional ocean modeling system” [Ocean Model. 167 (2021) 101889]

2022 ◽  
Vol 169 ◽  
pp. 101918
Author(s):  
Thiago Pires de Paula ◽  
Jose Antonio Moreira Lima ◽  
Clemente Augusto Souza Tanajura ◽  
Marcelo Andrioni ◽  
Renato Parkinson Martins ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Mesoscale Eddies ◽  
Ocean Model ◽  
Sao Paulo ◽  
Ocean Modeling ◽  
São Paulo ◽  
Regional Ocean Modeling System ◽  
Ocean Data Assimilation ◽  
The Impact

scholarly journals A Numerical Study on the Impact of High-Frequency Winds on the Peru Upwelling System during 2014–2016

2019 ◽  
Vol 7 (5) ◽  
pp. 161
Author(s):  
Linhui Wang ◽  
Huiwang Gao ◽  
Jie Shi ◽  
Lian Xie
Keyword(s):  
High Frequency ◽  
Numerical Study ◽  
Heat Budget ◽  
Vertical Mixing ◽  
Ocean Modeling ◽  
Wind Forcing ◽  
Regional Ocean Modeling System ◽  
Upwelling System ◽  
Budget Analysis ◽  
The Impact

The contribution of high-frequency wind to the Peruvian upwelling system during 2014–2016 was studied using the Regional Ocean Modeling System (ROMS), forced by four different temporal resolution (six-hourly, daily, weekly, and monthly) wind forcing. A major effect of the high-frequency wind is its warming of the water at all depths along the Peruvian coast. The mechanism for the temperature changes induced by high-frequency wind forcing was analyzed through heat budget analysis, which indicated a three-layer structure. Vertical advection plays a leading role in the warming of the mixed layer (0–25 m), and enhanced vertical mixing balances the warming effect. Analysis suggests that around the depths of 25–60 m, vertical mixing warms the water by bringing heat from the surface to deeper depths. In waters deeper than 60 m, the effect of vertical mixing is negligible. The differences among the oceanic responses in the sensitivity experiments suggest that wind forcing containing variabilities at higher than synoptic frequencies must be included in the atmospheric forcing in order to properly simulate the Peru upwelling system.

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