SPCZ zonal events and downstream influence on surface ocean conditions in the Indonesian Throughflow region

Braddock K. Linsley (1) , Henry C. Wu (2, 3) , Tim Rixen (4, 5) , Christopher D. Charles (6) , Arnold L. Gordon (1, 7) , Michael D. Moore (8)

1 LDEO - Lamont-Doherty Earth Observatory
2 LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 ZMT - Leibniz Centre for Tropical Marine Research
5 Institute of Geology, University of Hamburg, Hamburg 20146, Germany
6 SIO - UC San Diego - Scripps Institution of Oceanography
7 Department of Earth and Environmental Sciences [New York]
8 Chercheur indépendant

Seasonal surface freshening of the Makassar Strait, the main conduit of the Indonesian Throughflow (ITF), is a key factor controlling the ITF. Here we present a 262 year reconstruction of seasonal sea-surface-salinity variability from 1742 to 2004 Common Era by using coral δ¹⁸O records from the central Makassar Strait. Our record reveals persistent seasonal freshening and also years with significant truncations of seasonal freshening that correlate exactly with South Pacific Convergence Zone (SPCZ) zonal events >4000 km to the east. During these events, the SPCZ dramatically rotates ~15° north to near the equator and stronger westward flowing South Pacific boundary currents force higher-salinity water through the Makassar Strait in February–May halting the normal seasonal freshening in the strait. By these teleconnections, our Makassar coral δ¹⁸O series provides the first record of the recurrence interval of these zonal SPCZ events and demonstrates that they have occurred on a semiregular basis since the mid-1700s.

Mots clés: SPCZ; SPCZ zonal events; South Pacific Convergence Zone; Porites coral δ¹⁸O

Domaines: Géophysique [physics.geo-ph]; Océanographie

Braddock K. Linsley, Henry C. Wu, Tim Rixen, Christopher D. Charles, Arnold L. Gordon, et al.. SPCZ zonal events and downstream influence on surface ocean conditions in the Indonesian Throughflow region. Geophysical Research Letters, 2017, 44 (1), pp.293-303 ⟨10.1002/2016GL070985⟩. ⟨hal-01436736⟩