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Footprints of IOD and ENSO in the Kenyan coral record
Author(s) -
Nakamura Nobuko,
Kayanne Hajime,
Iijima Hiroko,
McClanahan Timothy R.,
Behera Swadhin K.,
Yamagata Toshio
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl049877
Subject(s) - kenya , coral , oceanography , el niño southern oscillation , environmental science , geology , fishery , climatology , biology , ecology
Low‐frequency variations in the seasonally phase‐locked signal of the Indian Ocean Dipole (IOD) and the Pacific El Niño/Southern Oscillation (ENSO) recorded in 115‐year coral δ 18 O variability from Kenyan coast, the tropical western Indian Ocean, were investigated. A comparison of the monthly coral δ 18 O 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 ENSO‐induced signals do not appear clearly as the positive sea surface temperature (SST) and rainfall anomalies in the monthly coral record. Moreover, annual mean coral δ 18 O 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 Niño 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.