Decadal surface ocean variability in the lower Gulf of California: Records for the past 300 years
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| Format: | Artículo científico |
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Universidad Nacional Autónoma de México
2003
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| author | Gladys Bernal Franco |
| author_facet | Gladys Bernal Franco |
| contents | Decadal surface ocean variability in the lower Gulf of California: Records for the past 300 years Gladys Bernal Franco Adolfo Molina Cruz Juan Carlos Herguera Ciencias de la Tierra PDO ENSO Oceanographic decadal variability tropical and equatorial variability oxygen isotopes in planktic foraminifera Recent observational and theoretical studies of the Gulf of California have produced some new ideas and models about itscirculation patterns and the controls on interannual to decadal timescales, that call on the importance of the tropical and equatorialPacific as the main region of forcing. The available instrumental record for this region is of short duration, reaching back only intothe early 1980s, which coupled with the poor resolution for previous years limits the validation of these models on longer timescales.To overcome the shortness of this record we resort to a reconstruction of SST variability for the last two centuries with the aid ofthe oxygen stable isotopic composition of calcitic shells preserved in the high-resolution laminated sediments that accumulate onthe sea-floor of the La Paz basin, off the Baja California Peninsula eastern margin. From the analysis of the instrumental record wefound that winter sea surface temperatures (SSTs) show greater variability from year to year than summer SSTs. Longer recordsfurther show a change in cold season temperatures with a trend towards warmer values at the turn of the last century, while thewarm season SSTs show no corresponding trend, which underlines the sensitivity of cooler months to interannual SST variabilityin this region. We further present an extended SST record for the past three centuries based on a reconstruction from the stableoxygen isotopic composition of the planktic foraminifer Globigerina bulloides (dOrbigny), shown to have its maximum productionin the lower Gulf of California during the winter-spring season. This paleothermometer shows mean winter SSTs similar tothe instrumentally recorded ones for the last 170 years while for the period between 1700 to 1830 shows cooler winters alternatingwith relatively warmer ones. The variability in winter SSTs on interannual to decadal timescales seem to be modulated by lowfrequencyENSO variability, possibly through higher frequency and intensity of El Niño/La Niña events that temporarily locksurface ocean temperatures into warm/cold decadal periods, thus tracking tropical oceanographic variability on decadal timescalesfor the past two centuries through ocean driven feedbacks. 2003 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56842311 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.3 Vol.42 |
| format | Artículo científico |
| id | redalyc_56842311 |
| institution | Redalyc |
| language | en |
| publishDate | 2003 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Decadal surface ocean variability in the lower Gulf of California: Records for the past 300 years Gladys Bernal Franco Ciencias de la Tierra PDO ENSO Oceanographic decadal variability tropical and equatorial variability oxygen isotopes in planktic foraminifera Decadal surface ocean variability in the lower Gulf of California: Records for the past 300 years Gladys Bernal Franco Adolfo Molina Cruz Juan Carlos Herguera Ciencias de la Tierra PDO ENSO Oceanographic decadal variability tropical and equatorial variability oxygen isotopes in planktic foraminifera Recent observational and theoretical studies of the Gulf of California have produced some new ideas and models about itscirculation patterns and the controls on interannual to decadal timescales, that call on the importance of the tropical and equatorialPacific as the main region of forcing. The available instrumental record for this region is of short duration, reaching back only intothe early 1980s, which coupled with the poor resolution for previous years limits the validation of these models on longer timescales.To overcome the shortness of this record we resort to a reconstruction of SST variability for the last two centuries with the aid ofthe oxygen stable isotopic composition of calcitic shells preserved in the high-resolution laminated sediments that accumulate onthe sea-floor of the La Paz basin, off the Baja California Peninsula eastern margin. From the analysis of the instrumental record wefound that winter sea surface temperatures (SSTs) show greater variability from year to year than summer SSTs. Longer recordsfurther show a change in cold season temperatures with a trend towards warmer values at the turn of the last century, while thewarm season SSTs show no corresponding trend, which underlines the sensitivity of cooler months to interannual SST variabilityin this region. We further present an extended SST record for the past three centuries based on a reconstruction from the stableoxygen isotopic composition of the planktic foraminifer Globigerina bulloides (dOrbigny), shown to have its maximum productionin the lower Gulf of California during the winter-spring season. This paleothermometer shows mean winter SSTs similar tothe instrumentally recorded ones for the last 170 years while for the period between 1700 to 1830 shows cooler winters alternatingwith relatively warmer ones. The variability in winter SSTs on interannual to decadal timescales seem to be modulated by lowfrequencyENSO variability, possibly through higher frequency and intensity of El Niño/La Niña events that temporarily locksurface ocean temperatures into warm/cold decadal periods, thus tracking tropical oceanographic variability on decadal timescalesfor the past two centuries through ocean driven feedbacks. 2003 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56842311 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.3 Vol.42 |
| title | Decadal surface ocean variability in the lower Gulf of California: Records for the past 300 years |
| topic | Ciencias de la Tierra PDO ENSO Oceanographic decadal variability tropical and equatorial variability oxygen isotopes in planktic foraminifera |
| url | https://www.redalyc.org/articulo.oa?id=56842311 |