Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses
The Zapiola Rise (ZR) is a singular sedimentary deposit about 1200 m in height and 1500 km in width located in the Argentine Basin. In situ and satellite observations have revealed the presence of an intense counterclockwise circulation around the feature, with a volume transport comparable to those...
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09670637_v56_n7_p1077_Saraceno http://hdl.handle.net/20.500.12110/paper_09670637_v56_n7_p1077_Saraceno |
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paper:paper_09670637_v56_n7_p1077_Saraceno2023-06-08T15:58:43Z Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses Saraceno, Martin Interannual variability South Atlantic circulation Zapiola Rise Anticyclonic circulation Anticyclonic flow Barotropic Global climates High frequency HF In-situ Interannual variability Long-term variations Low frequency variability Low-frequency signals Mesoscale activity Ocean circulation Satellite altimetry Satellite observations Sedimentary deposits South Atlantic South Atlantic circulation Surface velocity Volume transport Water mass Zapiola Rise Climatology Ocean engineering Ocean currents annual variation anticyclone climate variation mass transport mixing oceanic circulation satellite altimetry time series water mass Argentine Basin Atlantic Ocean Zapiola Rise The Zapiola Rise (ZR) is a singular sedimentary deposit about 1200 m in height and 1500 km in width located in the Argentine Basin. In situ and satellite observations have revealed the presence of an intense counterclockwise circulation around the feature, with a volume transport comparable to those of the major ocean currents. The existence of a very low-frequency variability of the transport associated with the anticyclonic circulation is documented for the first time. As the Zapiola anticyclonic circulation plays a significant role in the mixing of the strongly contrasted water masses of the South Atlantic, variations in the anticyclonic transport can have a major impact on the mixing, hence a role in global climate variability. The circulation was clearly anticyclonic in the periods 1993-1999 and 2002-2007. In contrast, the 1999-2001 period did not show evidence of an anticyclonic flow in the mean surface velocity field. Moreover, the analysis of the weekly fields during that period of time revealed a cyclonic pattern from time to time. Previous work has shown that the flow can be considered as purely barotropic over the ZR region. A 15-year time-series of the transport was produced using absolute altimeter-derived geostrophic velocities. The estimated transport presents high-frequency variability associated with mesoscale activity superimposed on a low-frequency signal. The amplitude of the estimated transport is in good agreement with the only in situ-derived estimation available (80 Sv, January 1993). The low-frequency signal presents a minimum during the period 1999-2001, further suggesting that at times the Zapiola anticyclonic flow may have significantly decreased in strength or even vanished. Possible causes of the low-frequency variability are discussed. © 2009 Elsevier Ltd. All rights reserved. Fil:Saraceno, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2009 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09670637_v56_n7_p1077_Saraceno http://hdl.handle.net/20.500.12110/paper_09670637_v56_n7_p1077_Saraceno |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Interannual variability South Atlantic circulation Zapiola Rise Anticyclonic circulation Anticyclonic flow Barotropic Global climates High frequency HF In-situ Interannual variability Long-term variations Low frequency variability Low-frequency signals Mesoscale activity Ocean circulation Satellite altimetry Satellite observations Sedimentary deposits South Atlantic South Atlantic circulation Surface velocity Volume transport Water mass Zapiola Rise Climatology Ocean engineering Ocean currents annual variation anticyclone climate variation mass transport mixing oceanic circulation satellite altimetry time series water mass Argentine Basin Atlantic Ocean Zapiola Rise |
| spellingShingle |
Interannual variability South Atlantic circulation Zapiola Rise Anticyclonic circulation Anticyclonic flow Barotropic Global climates High frequency HF In-situ Interannual variability Long-term variations Low frequency variability Low-frequency signals Mesoscale activity Ocean circulation Satellite altimetry Satellite observations Sedimentary deposits South Atlantic South Atlantic circulation Surface velocity Volume transport Water mass Zapiola Rise Climatology Ocean engineering Ocean currents annual variation anticyclone climate variation mass transport mixing oceanic circulation satellite altimetry time series water mass Argentine Basin Atlantic Ocean Zapiola Rise Saraceno, Martin Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses |
| topic_facet |
Interannual variability South Atlantic circulation Zapiola Rise Anticyclonic circulation Anticyclonic flow Barotropic Global climates High frequency HF In-situ Interannual variability Long-term variations Low frequency variability Low-frequency signals Mesoscale activity Ocean circulation Satellite altimetry Satellite observations Sedimentary deposits South Atlantic South Atlantic circulation Surface velocity Volume transport Water mass Zapiola Rise Climatology Ocean engineering Ocean currents annual variation anticyclone climate variation mass transport mixing oceanic circulation satellite altimetry time series water mass Argentine Basin Atlantic Ocean Zapiola Rise |
| description |
The Zapiola Rise (ZR) is a singular sedimentary deposit about 1200 m in height and 1500 km in width located in the Argentine Basin. In situ and satellite observations have revealed the presence of an intense counterclockwise circulation around the feature, with a volume transport comparable to those of the major ocean currents. The existence of a very low-frequency variability of the transport associated with the anticyclonic circulation is documented for the first time. As the Zapiola anticyclonic circulation plays a significant role in the mixing of the strongly contrasted water masses of the South Atlantic, variations in the anticyclonic transport can have a major impact on the mixing, hence a role in global climate variability. The circulation was clearly anticyclonic in the periods 1993-1999 and 2002-2007. In contrast, the 1999-2001 period did not show evidence of an anticyclonic flow in the mean surface velocity field. Moreover, the analysis of the weekly fields during that period of time revealed a cyclonic pattern from time to time. Previous work has shown that the flow can be considered as purely barotropic over the ZR region. A 15-year time-series of the transport was produced using absolute altimeter-derived geostrophic velocities. The estimated transport presents high-frequency variability associated with mesoscale activity superimposed on a low-frequency signal. The amplitude of the estimated transport is in good agreement with the only in situ-derived estimation available (80 Sv, January 1993). The low-frequency signal presents a minimum during the period 1999-2001, further suggesting that at times the Zapiola anticyclonic flow may have significantly decreased in strength or even vanished. Possible causes of the low-frequency variability are discussed. © 2009 Elsevier Ltd. All rights reserved. |
| author |
Saraceno, Martin |
| author_facet |
Saraceno, Martin |
| author_sort |
Saraceno, Martin |
| title |
Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses |
| title_short |
Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses |
| title_full |
Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses |
| title_fullStr |
Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses |
| title_full_unstemmed |
Long-term variation in the anticyclonic ocean circulation over the Zapiola Rise as observed by satellite altimetry: Evidence of possible collapses |
| title_sort |
long-term variation in the anticyclonic ocean circulation over the zapiola rise as observed by satellite altimetry: evidence of possible collapses |
| publishDate |
2009 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09670637_v56_n7_p1077_Saraceno http://hdl.handle.net/20.500.12110/paper_09670637_v56_n7_p1077_Saraceno |
| work_keys_str_mv |
AT saracenomartin longtermvariationintheanticyclonicoceancirculationoverthezapiolariseasobservedbysatellitealtimetryevidenceofpossiblecollapses |
| _version_ |
1768543523949248512 |