Footprints of IOD and ENSO in the Kenyan coral record
Nakamura, N.; Kayanne, H.; Iijima, H.; McClanahan, T. R.; Behera, S.K.; Yamagata, T. (2011). Footprints of IOD and ENSO in the Kenyan coral record. Geophys. Res. Lett. 38. dx.doi.org/10.1029/2011GL049877
In: Geophysical Research Letters. American Geophysical Union: Washington. ISSN 0094-8276; e-ISSN 1944-8007, meer
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| Author keywords |
ENSO signal, IOD, coral d18O, seasonally stratified analysis, the western Indian Ocean |
| Auteurs | | Top |
- Nakamura, N.
- Kayanne, H.
- Iijima, H.
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- McClanahan, T. R.
- Behera, S.K.
- Yamagata, T.
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| Abstract |
Low-frequency variations in the seasonally phaselocked signal of the Indian Ocean Dipole (IOD) and the Pacific El Nino/Southern Oscillation (ENSO) recorded in 115-year coral delta O-18 variability from Kenyan coast, the tropical western Indian Ocean, were investigated. A comparison of the monthly coral delta O-18 corresponding to IOD and ENSO years shows that Kenyan coral distinctly records the East African Short Rain anomaly related to the IOD variability in January, a few months after the Short Rain peak due to oceanographic condition. On the other hand, the ENSOinduced signals do not appear clearly as the positive sea surface temperature (SST) and rainfall anomalies in the monthly coral record. Moreover, annual mean coral d18O and ENSO show only a weak coherence at the periodicity of 4 to 5 years. These results support the suggestion that the IOD is the dominant climate mode rather than ENSO in the Kenyan coast. The coral records indicate that the negative IOD- like anomalously cold SST condition in the western Indian Ocean precedes the evolution of the Pacific El Nino by one year. The anomalously cold SST condition was prominent in the late 19th century, but weakened in the 20th century. This retreat of the cold SST condition due to warming of the western tropical Indian Ocean may influence the nature of the Pacific ENSO. |
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