scholarly journals CHARACTERISTICS AND VARIABILITY OF THE FLORES ITF AND ITS COHERENCE WITH THE SOUTH JAVA COASTAL CURRENT

2018 ◽  
Vol 9 (2) ◽  
pp. 537-556 ◽  
Author(s):  
Agus S. Atmadipoera ◽  
Paradita Hasanah
Keyword(s):  
High Velocity ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Vertical Dimension ◽  
Coastal Current ◽  
Indonesian Throughflow ◽  
The South ◽  
Near Surface ◽  
Transport Volume

Characteristics and transport variability of the Indonesian Throughflow (ITF) in the western Flores Sea (FS) and its coherency with the South Java Coastal Current (SJCC) fluctuation are investigated using validated ocean general circulation model output (2008-2014) from the INDESO configuration.  The results show that near-surface circulation in the study area is characterized by two distinct regimes:  strong southwestward ITF flow and quasi-transient anti-cyclonic eddies. Vertical dimension of ITF crossing 7.5°S is about 112 km width, 250 m depth, and high velocity core at thermocline >0.3 m/s.  Transport volume estimates along this latitude is -4.95 Sv (southward).  Bifurcation of ITF flow appears north offshore Lombok Island where -2.92 Sv flowing into Lombok Strait and the rest flowing eastward into FS. Meanwhile, vertical dimension of SJCC crossing 114°E is about 89 km width, 120 m depth, and high velocity core at sub-surface >0.35 m/s. Mean transport of SJCC is +2.65 Sv. Coherency between Flores ITF and SJCC transport variability on intra-seasonal scales is significantly high, e.g., on 30 day period (coher=0.92) and phase-lags of 0.6-day with SJCC leading to Flores ITF. This result confirmed previous studies, related to intrusion of coastally trapped Kelvin waves into Flores Sea via Lombok Strait. Keywords: Indonesian Throughflow, western Flores Sea, South Java Coastal Current

scholarly journals A Short Surface Pathway of the Subsurface Indonesian Throughflow Water from the Java Coast Associated with Upwelling, Ekman Transport, and Subduction

2010 ◽  
Vol 2010 ◽  
pp. 1-15 ◽  
Author(s):  
Vinu Valsala ◽  
Shamil Maksyutov
Keyword(s):  
Indian Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Tropical Indian Ocean ◽  
Ocean General Circulation Model ◽  
Reanalysis Data ◽  
Ekman Transport ◽  
Indonesian Throughflow ◽  
The South ◽  
Wind Stress Curl

A surface pathway of the subsurface Indonesian Throughflow (ITF) in the southeastern Indian Ocean is proposed using a combined analysis of Lagrangian particles and passive tracers derived from two independent tools: an Ocean General Circulation Model (OGCM) and Simple Ocean Data Assimilation (SODA.2.0.2) reanalysis data. This newly suggested pathway follows the processes in succession as upwelling in the south Java coast, offshore Ekman drift and subduction into the thermocline centered on 20∘S. The upwelling of subsurface ITF along the south Java coast is found to occur from August to October. Upon surfacing, the ITF advects southwestward being trapped in the surface Ekman layer for an approximate period of 260 days and reaches the southeastern tropical Indian Ocean subduction zone centered on 20∘S which is demarcated by the Zero Wind Stress Curl (ZWSC) and subducts there. The particle trajectory revealed that during the subduction within the ZWSC region, the surface eastward flow above 120 m depth carries the particle about 10∘ to the east and westward flow below this depth carries the particle to the western Indian Ocean along the thermocline. These pathways are confirmed by a series of tracer experiments using SODA reanalysis data. The effects of vertical mixing and entrainment on the surfacing of the ITF at south Java coast were identified.

scholarly journals Tropical Atlantic Mixed Layer Buoyancy Seasonality: Atmospheric and Oceanic Physical Processes Contributions

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 649
Author(s):  
Ibrahima Camara ◽  
Juliette Mignot ◽  
Nicolas Kolodziejczyk ◽  
Teresa Losada ◽  
Alban Lazar
Keyword(s):  
Heat Flux ◽  
Mixed Layer ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Brazilian Coast ◽  
Freshwater Flux ◽  
Physical Processes ◽  
Inter Tropical Convergence Zone ◽  
Near Surface

This study investigates the physical processes controlling the mixed layer buoyancy using a regional configuration of an ocean general circulation model. Processes are quantified by using a linearized equation of state, a mixed-layer heat, and a salt budget. Model results correctly reproduce the observed seasonal near-surface density tendencies. The results indicate that the heat flux is located poleward of 10° of latitude, which is at least three times greater than the freshwater flux that mainly controls mixed layer buoyancy. During boreal spring-summer of each hemisphere, the freshwater flux partly compensates the heat flux in terms of buoyancy loss while, during the fall-winter, they act together. Under the seasonal march of the Inter-tropical Convergence Zone and in coastal areas affected by the river, the contribution of ocean processes on the upper density becomes important. Along the north Brazilian coast and the Gulf of Guinea, horizontal and vertical processes involving salinity are the main contributors to an upper water change with a contribution of at least twice as much the temperature. At the equator and along the Senegal-Mauritanian coast, vertical processes are the major oceanic contributors. This is mainly due to the vertical gradient of temperature at the mixed layer base in the equator while the salinity one dominates along the Senegal-Mauritania coast.

scholarly journals Modeling the present and future impact of aviation on climate: an AOGCM approach with online coupled chemistry

2013 ◽  
Vol 13 (19) ◽  
pp. 10027-10048 ◽  
Author(s):  
P. Huszar ◽  
H. Teyssèdre ◽  
M. Michou ◽  
A. Voldoire ◽  
D. J. L. Olivié ◽  
...  
Keyword(s):  
Co2 Emissions ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Impacts ◽  
Ozone Production ◽  
The Arctic ◽  
Near Surface ◽  
Aviation Emissions ◽  
The Impact

Abstract. Our work is among the first that use an atmosphere-ocean general circulation model (AOGCM) with online chemistry to evaluate the impact of future aviation emissions on temperature. Other particularities of our study include non-scaling to the aviation emissions, and the analysis of models' transient response using ensemble simulations. The model we use is the Météo-France CNRM-CM5.1 earth system model extended with the REPROBUS chemistry scheme. The time horizon of our interest is 1940–2100, assuming the A1B SRES scenario. We investigate the present and future impact of aviation emissions of CO2, NOx and H2O on climate, taking into account changes in greenhouse gases, contrails and contrail-induced cirrus (CIC). As in many transport-related impact studies, we distinguish between the climate impacts of CO2 emissions and those of non-CO2 emissions. Aviation-produced aerosol is not considered in the study. Our modeling system simulated a notable sea-ice bias in the Arctic, and therefore results concerning the surface should be viewed with caution. The global averaged near-surface CO2 impact reaches around 0.1 K by the end of the 21st century, while the non-CO2 impact reaches 0.2 K in the second half of the century. The NOx emissions impact is almost negligible in our simulations, as our aviation-induced ozone production is small. As a consequence, the non-CO2 signal is very similar to the CIC signal. The seasonal analysis shows that the strongest warming due to aviation is modeled for the late summer and early autumn. In the stratosphere, a significant cooling is attributed to aviation CO2 emissions (−0.25 K by 2100). A −0.3 K temperature decrease is modeled when considering all the aviation emissions, but no significant signal appears from the CIC or NOx forcings in the stratosphere.

scholarly journals Volume Transport Variability in the Western Equatorial Pacific and its Relations to Halmahera Throughflow

2021 ◽  
Vol 29 (2) ◽  
Author(s):  
Marlin Chrisye Wattimena ◽  
Agus Saleh Atmadipoera ◽  
Mulia Purba ◽  
I Wayan Nurjaya ◽  
Fadli Syamsudin
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Volume Transport ◽  
Equatorial Pacific ◽  
Equatorial Pacific Ocean ◽  
Western Equatorial Pacific ◽  
North Equatorial Counter Current ◽  
Mindanao Current ◽  
Transport Volume

This study investigates the coherency of volume transport between Halmahera throughflow and current major system in the western equatorial Pacific Ocean (Mindanao Current – MC, New Guinea Coastal/Under Current – NGCC/NGCUC, and North Equatorial Counter Current – NECC). The validated daily ocean general circulation model datasets of INDESO (2010-2014) were used in this study. The results showed that the estimated average transport volume was 25.6 Sv flowing southward through MC, 34.5 Sv flowing eastward through NECC, 18.3 Sv flowing northwestward through NGCC/NGCUC, and 2.5 Sv flowing southward through the Halmahera Sea. The variability of volume transport was dominated by intraseasonal, semiannual, and annual time-scales. The increased transport of NECC corresponded to the intensification of MC and NGCC/NGCUC transports. NGCC/ NGCUC significantly controlled the South Pacific water inflow into the Halmahera Sea because of the positively high correlation between NGCC/NGCUC transport and Halmahera throughflow transport.

scholarly journals The dynamic connection of the Indonesian Throughflow, South Indian Ocean Countercurrent and the Leeuwin Current

2015 ◽  
Vol 12 (5) ◽  
pp. 2231-2256
Author(s):  
E. Lambert ◽  
D. Le Bars ◽  
W. P. M. de Ruijter
Keyword(s):  
Indian Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Coastal Current ◽  
Indonesian Throughflow ◽  
Boundary Current ◽  
South Indian Ocean ◽  
Leeuwin Current ◽  
South Indian ◽  
The Indian Ocean

Abstract. East of Madagascar, wind and surface buoyancy fluxes reinforce each other, leading to frontogenesis, outcrop and an eastward along-front flow: the South Indian Ocean Countercurrent (SICC). In the east the Leeuwin Current (LC) is a unique eastern boundary current which flows poleward along Australia. It is often described as a regional coastal current forced by an off-shore meridional density gradient or a sea surface slope, yet little is known of the forcing and dynamics that control these open ocean meridional gadients. To complete this understanding, we make use of both an ocean general circulation model and a conceptual two-layer model. The SICC impinges on west Australia and adds to a sea level slope and a southward geostrophic coastal jet: the Leeuwin Current. The SICC and the LC are thus dynamically connected. An observed transport maximum of the LC around 22° S is directly related to this impingement of the SICC. The circulation of the Indonesian Throughflow (ITF) through the Indian Ocean appears to be partly trapped in the upper layer north of the outcrop line and is redirected along this outcrop line to join the eastward flow of the SICC. Shutdown of the ITF in both models strongly decreases the Leeuwin Current transport and breaks the connection between the LC and SICC. In this case, most of the SICC was found to reconnect to the internal gyre circulation in the Indian Ocean. The Indonesian Throughflow, South Indian Ocean Countercurrent and the Leeuwin Current are thus dynamically coupled.

scholarly journals Seasonal Upwelling in the Northern Arafura Sea from Multi-datasets in 2017

2020 ◽  
Vol 28 (4) ◽  
Author(s):  
Agus Saleh Atmadipoera ◽  
Agits Agnia Almatin ◽  
Rina Zuraida ◽  
Yani Permanawati
Keyword(s):  
Mixed Layer ◽  
General Circulation ◽  
Standard Procedure ◽  
Subsurface Layer ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Surface Mixed Layer ◽  
Fisheries Resources ◽  
Arafura Sea ◽  
Transport Volume

Seasonal upwelling phenomenon in the Arafura Sea plays an important role on supplying upwelled nutrient-rich water to sustain biogeochemistry processes and thus contributes to high marine primary productivity and fisheries resources in this region. The objective of this research was to investigate physical process and dynamics of upwelling by analyzing stratification of seawater properties, evolution of surface ocean-atmosphere parameters, and current structure and transport volume in the northern Arafura Sea. The multi-datasets in 2017 were used in this study, acquired from field CTD measurement, satellite-derived sea surface parameters, and the ocean general circulation model outputs, which were processed and analyzed using the available standard procedure. It was found that upwelling event was associated with a sharp subsurface thin layer that upsloping isotherms (23.5 - 25.5°C), isohalines (33.50 - 34.25 psu), and isopycnals (21.8 - 23.2 kg/m³) from the shelf-break region to the inner shelf region at a distance of approximately 167 km. This barrier layer separated the first surface mixed layer from the second mixed layer beneath the subsurface layer. The model suggests that the current in these two layers is in the opposite direction, to the west in the first layer as a response to the Ekman drift and to the east in the second layer as a current extension from deep Aru basin. Therefore, upwelling dynamics here is not only generated by the southeasterly monsoon winds from May (onset) to November (termination) that transport warm and fresh surface water away from the shelf, but also modulated by the presence of strong inflow currents beneath subsurface that supply colder saltier nutrient-rich water into the shelf. During the upwelling period, mean transport volume in the upper 25 m depth between Aru and Papua at 134.25°E was -0.28 (±0.34) Sv (westward), but the transport volume between 25m and 110m depth was +1.06 (±0.29) Sv (eastward), suggesting this inflow may regulate the upwelling and supply Arafura shelf water.

scholarly journals The South China Sea Throughflow Retrieved from Climatological Data*

2009 ◽  
Vol 39 (3) ◽  
pp. 753-767 ◽  
Author(s):  
Max Yaremchuk ◽  
Julian McCreary ◽  
Zuojun Yu ◽  
Ryo Furue
Keyword(s):  
South China Sea ◽  
General Circulation Model ◽  
South China ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Luzon Strait ◽  
The South China Sea ◽  
China Sea ◽  
Ocean General Circulation

Abstract The salinity distribution in the South China Sea (SCS) has a pronounced subsurface maximum from 150–220 m throughout the year. This feature can only be maintained by the existence of a mean flow through the SCS, consisting of a net inflow of salty North Pacific tropical water through the Luzon Strait and outflow through the Mindoro, Karimata, and Taiwan Straits. Using an inverse modeling approach, the authors show that the magnitude and space–time variations of the SCS thermohaline structure, particularly for the salinity maximum, allow a quantitative estimate of the SCS throughflow and its distribution among the three outflow straits. Results from the inversion are compared with available observations and output from a 50-yr simulation of a highly resolved ocean general circulation model. The annual-mean Luzon Strait transport is found to be 2.4 ± 0.6 Sv (Sv ≡ 106 m3 s−1). This inflow is balanced by the outflows from the Karimata (0.3 ± 0.5 Sv), Mindoro (1.5 ± 0.4), and Taiwan (0.6 ± 0.5 Sv) Straits. Results of the inversion suggest that the Karimata transport tends to be overestimated in numerical models. The Mindoro Strait provides the only passage from the SCS deeper than 100 m, and half of the SCS throughflow (1.2 ± 0.3 Sv) exits the basin below 100 m in the Mindoro Strait, a result that is consistent with a climatological run of a 0.1° global ocean general circulation model.

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