Oman coral δ 18 O seawater record suggests that Western Indian Ocean upwelling uncouples from the Indian Ocean Dipole during the global-warming hiatus

Takaaki K. Watanabe, Tsuyoshi Watanabe*, Atsuko Yamazaki, Miriam Pfeiffer, Michel R. Claereboudt

*المؤلف المقابل لهذا العمل

نتاج البحث: المساهمة في مجلةArticleمراجعة النظراء

10 اقتباسات (Scopus)

ملخص

The Indian Ocean Dipole (IOD) is an interannual mode of climate variability in the Indian Ocean that has intensified with 20 th century global-warming. However, instrumental data shows a global-warming hiatus between the late-1990s and 2015. It is presently not clear how the global-warming hiatus affects modes of climate variability such as the IOD, and their basin-wide ocean-atmosphere teleconnections. Here, we present a 26-year long, biweekly record of Sr/Ca and δ 18 O from a Porites coral drilled in the Gulf of Oman. Sea surface temperature (SST anom ) is calculated from Sr/Ca ratios, and seawater δ 18 O (δ 18 O sw-anom ) is estimated by subtracting the temperature component from coral δ 18 O. Our δ 18 O sw-anom record reveals a significant regime shift in 1999, towards lower mean δ 18 O sw values, reflecting intensified upwelling in the western Indian Ocean. Prior to the 1999 regime shift, our SST anom and δ 18 O sw-anom show a clear IOD signature, with higher values in the summer of positive-IOD years due to weakened upwelling. The IOD signature in SST anom and δ 18 O sw-anom disappears with the overall intensification of upwelling after the 1999 regime shift. The inferred increase in upwelling is likely driven by an intensified Walker circulation during the global-warming hiatus. Upwelling in the Western Indian Ocean uncouples from the IOD.

اللغة الأصليةEnglish
رقم المقال1887
دوريةScientific Reports
مستوى الصوت9
رقم الإصدار1
المعرِّفات الرقمية للأشياء
حالة النشرPublished - ديسمبر 1 2019

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