scholarly journals Brazil Current volume transport variability during 2009‐2015 from a long‐term moored array at 34.5°S

2021 ◽  
Author(s):  
M. P. Chidichimo ◽  
A. R. Piola ◽  
C. S. Meinen ◽  
R. C. Perez ◽  
E. J. D. Campos ◽  
...  
Keyword(s):  
Volume Transport ◽  
Current Volume ◽  
Brazil Current

scholarly journals The Iceland-Faroe Slope Jet: a conduit for dense water toward the Faroe Bank Channel overflow

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Stefanie Semper ◽  
Robert S. Pickart ◽  
Kjetil Våge ◽  
Karin Margretha H. Larsen ◽  
Hjálmar Hátún ◽  
...  
Keyword(s):  
Volume Transport ◽  
Meridional Overturning Circulation ◽  
Common Source ◽  
Overturning Circulation ◽  
Nordic Seas ◽  
Dense Water ◽  
The North ◽  
Denmark Strait ◽  
Meridional Overturning

Abstract Dense water from the Nordic Seas passes through the Faroe Bank Channel and supplies the lower limb of the Atlantic Meridional Overturning Circulation, a critical component of the climate system. Yet, the upstream pathways of this water are not fully known. Here we present evidence of a previously unrecognised deep current following the slope from Iceland toward the Faroe Bank Channel using high-resolution, synoptic shipboard observations and long-term measurements north of the Faroe Islands. The bulk of the volume transport of the current, named the Iceland-Faroe Slope Jet (IFSJ), is relatively uniform in hydrographic properties, very similar to the North Icelandic Jet flowing westward along the slope north of Iceland toward Denmark Strait. This suggests a common source for the two major overflows across the Greenland-Scotland Ridge. The IFSJ can account for approximately half of the total overflow transport through the Faroe Bank Channel, thus constituting a significant component of the overturning circulation in the Nordic Seas.

scholarly journals Variability in the Deep Overflow through the Heng-Chun Ridge of the Luzon Strait

2019 ◽  
Vol 49 (3) ◽  
pp. 811-825 ◽  
Author(s):  
Ruijie Ye ◽  
Chun Zhou ◽  
Wei Zhao ◽  
Jiwei Tian ◽  
Qingxuan Yang ◽  
...  
Keyword(s):  
Deep Water ◽  
Volume Transport ◽  
Luzon Strait ◽  
Bottom Current ◽  
Detailed Structure ◽  
Intraseasonal Variations ◽  
First Time ◽  
Water Overflow ◽  
Main Entrance

AbstractThe deep water overflow at three gaps in the Heng-Chun Ridge of the Luzon Strait is investigated based on long-term continuous mooring observations. For the first time, these observations enable us to assess the detailed structure and variability in the deep water overflow directly spilling into the South China Sea (SCS). The strong bottom-intensified flows at moorings WG2 and WG3 intrude into the deep SCS with maximum along-stream velocities of 19.2 ± 9.9 and 15.2 ± 6.8 cm s−1, respectively, at approximately 50 m above the bottom. At mooring WG1, the bottom current revealed spillage into the Luzon Trough from the SCS. The volume transport estimates are 0.73 ± 0.08 Sv at WG2 and 0.45 ± 0.02 Sv at WG3, suggesting that WG2 is the main entrance for the deep water overflow crossing the Heng-Chun Ridge into the SCS. By including the long-term observational results from previous studies, the pathway of the deep water overflow through the Luzon Strait is also presented. In addition, significant intraseasonal variations with dominant time scales of approximately 26 days at WG2 and WG3 have been revealed, which tend to be enhanced in spring and may reverse the deep water overflow.

Pathways connecting the North Brazil Current and the RAPID line

2021 ◽  
Author(s):  
Kimberley Drouin ◽  
M Susan Lozier ◽  
F Javier Beron-Vera ◽  
Phillip Miron ◽  
M Josefina Olascoaga
Keyword(s):  
Three Dimensional ◽  
Volume Transport ◽  
Florida Current ◽  
The North ◽  
Dynamical Systems Analysis ◽  
Brazil Current ◽  
North Brazil ◽  
North Brazil Current ◽  
The Caribbean ◽  
Surface Drifters

<p>The North Brazil Current is considered a bottleneck in the South Atlantic, responsible for funneling upper-ocean waters into the North Atlantic. This work explores the surface and subsurface pathways that connect the North Brazil Current to the RAPID line. To that extent, observational trajectories from surface drifters and Argo floats are used in conjunction with Markov chain theory and tools from dynamical systems analysis to compute probable pathways. More specifically, these pathways are computed as ensembles of paths transitioning directly between the North Brazil Current and the RAPID line. In addition, simulated trajectories will be used (1) to assess how representative the two-dimensional observational trajectories are of the three-dimensional circulation, and (2) to compute the associated volume transport of different pathways. Preliminary results suggest that two dominant pathways connect the North Brazil Current and the RAPID line. First, is the traditional pathway through the Caribbean Sea and Gulf of Mexico, which carries waters to the Florida Current, and second is a more direct route east of the Caribbean that supplies waters to the Antilles Current and the basin interior.  </p>

Long-term observations of the strongest inflow branch of warm water to the Arctic Mediterranean

2020 ◽  
Author(s):  
Bogi Hansen ◽  
Karin M. H. Larsen ◽  
Hjálmar Hátún ◽  
Svein Østerhus
Keyword(s):  
Satellite Altimetry ◽  
Saline Water ◽  
Accurate Determination ◽  
Volume Transport ◽  
High Accuracy ◽  
The Arctic ◽  
Boundary Current ◽  
Data Set

<p>Warm and saline water from the North Atlantic enters the Arctic Mediterranean through three gaps. The strongest of these three flows is the inflow between Iceland and Faroes, which is focused into a narrow boundary current north of the Faroes. This boundary current, the Faroe Current, has been observed with regular CTD cruises since 1988 and with moored ADCPs since 1997, as well as satellite altimetry since 1993. Once calibrated by the long-term ADCP measurements, the satellite altimetry is found to yield high-accuracy determination of the velocity field and volume transport down to fixed depth. Due to geostrophic adjustment, satellite altimetry combined with CTD data also allow fairly accurate determination of the depth of the Atlantic layer. From the combined data set, monthly transport time series have been generated for the period Jan 1993 to April 2019. Over the period, the annually averaged volume transport of Atlantic water in the Faroe Current seems to have increased slightly, while the heat transport relative to an outflow temperature of 0°C increased by 13%, significant at the 95% level. The salinity increased from the mid-1990s to around 2010, after which it has decreased, especially after 2016, leading to the lowest salinities in the whole period since 1988. To stay updated on a possible inflow reduction due to reduced thermohaline ventilation caused by this freshening, the future monitoring system of the Faroe Current is planned to be expanded with moored PIES (Pressure Inverted Echo Sounders). An experiment with two PIES in 2017-2019 has documented that these instruments allow high-accuracy monitoring of the depth of the Atlantic layer on the section, which combined with satellite altimetry and CTD observations should give more accurate transport estimates.</p>

scholarly journals VARIABILIDADE DO SISTEMA CORRENTE DO BRASIL ASSOCIADA AOS CENÁRIOS DE MUDANÇAS CLIMÁTICAS A1FI E B1

2016 ◽  
Vol 19 (3) ◽  
Author(s):  
Carina Stefoni Böck ◽  
Luiz Paulo De Freitas Assad ◽  
Luiz Landau
Keyword(s):  
Climate Change ◽  
Heat Flux ◽  
Wavelet Analysis ◽  
Climate Changes ◽  
Climate Model ◽  
Current System ◽  
Volume Transport ◽  
Climate Change Scenarios ◽  
Intergovernmental Panel ◽  
Brazil Current

The aim of this work is to investigate the behavior of volume transport and advective heat flux patterns which are related to the Brazil Current System (BCS) according to the climate change scenarios suggested by the Intergovernmental Panel on Climate Changes. The results deriving from the global model Climate Model version 2.1 (GFDL-CM2.1) for future scenarios of climate change A1FI and B1 and for the scenario that represents the climate in the Twentieth Century (20C3M) have been used in this work. Volume transport and advective heat flux integrated for the whole BCS as well as for each water mass which constitutes the system have been calculated applying these data. Estimates were made for three zonal sections (23ºS, 25ºS and 30ºS) and then were used in the Wavelet Analysis. The performed analysis showed the occurrence of interannual variability for the estimated properties in the region. It also showed that the BCS shows changes in both intensity and variability of these parameters when comparing A1FI and B1 to 20C3M. Results from Wavelet Analysis for the total volume transport and advective heat flux integrated per section show that the period between three and six years prevails in sections 23ºS and 25ºS. The variability in 30ºS however, is significantly higher than eight years. It could also be observed the change of the variability of the total volume transport and heat flux temporal series towards higher frequencies when they are submitted to A1FI and B1 climate changes scenarios.

scholarly journals The East Madagascar Current: Volume Transport and Variability Based on Long-Term Observations

2016 ◽  
Vol 46 (4) ◽  
pp. 1045-1065 ◽  
Author(s):  
Leandro Ponsoni ◽  
Borja Aguiar-González ◽  
Herman Ridderinkhof ◽  
Leo R. M. Maas
Keyword(s):  
Volume Transport ◽  
Altimeter Data ◽  
Surface Transport ◽  
Sea Level Anomalies ◽  
Anticyclonic Eddies ◽  
Satellite Altimeter Data ◽  
Observational Program ◽  
Good Agreement

AbstractThis study provides a long-term description of the poleward East Madagascar Current (EMC) in terms of its observed velocities, estimated volume transport, and variability based on both ~2.5 yr of continuous in situ measurements and ~21 yr of satellite altimeter data. An array of five moorings was deployed at 23°S off eastern Madagascar as part of the Indian–Atlantic Exchange in present and past climate (INATEX) observational program. On average, the EMC has a horizontal scale of about 60–100 km and is found from the surface to about 1000-m depth. Its time-averaged core is positioned at the surface, at approximately 20 km from the coast, with velocity of 79 (±21) cm s−1. The EMC mean volume transport is estimated to be 18.3 (±8.4) Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1). During the strongest events, maximum velocities and transport reach up to 170 cm s−1 and 50 Sv, respectively. A good agreement is found between the in situ transport estimated over the first 8 m of water column [0.32 (±0.13) Sv] with the altimetry-derived volume transport [0.28 (±0.09) Sv]. Results from wavelet analysis display a dominant nearly bimonthly (45–85 days) frequency band of transport variability, which explains about 41% of the transport variance. Altimeter data suggest that this band of variability is induced by the arrival of westward-propagating sea level anomalies, which in turn are likely represented by mesoscale cyclonic and anticyclonic eddies. Annual averages of the altimeter-derived surface transport suggest that interannual variabilities also play a role in the EMC system.

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