EVALUATING SOUTHERN RED-SEA CORALS AS A PROXY RECORD FOR THE ASIAN MONSOON

Coral palaeoclimatic studies are under way at many sites throughout th e wet tropics. However, arid environments have received less attention , Here we report a high-resolution, 63 yr record of coral delta(18)O a nd delta(13)C extracted from a Porites colony from the Dahlak Archipel ago, off the Eritrean coast, in the southern Red Sea. The annual cycle s of the coral delta(18)O and delta(13)C are inversely related while t heir inter-annual variations show a strong positive correlation, with similar inter-decadal trends. Inter-annual variations in coral delta(1 8)O show a relatively weak correlation with the southern Red Sea SST, but are strongly correlated with the Indian Ocean SST, especially on t he decadal time-scale. The range of the inter-annual variations in the coral delta(18)O is high compared to changes in local SST, due to the amplifying effect of simultaneous changes in water isotopic compositi on, Due to this amplification of the climate signal the coral provides a better indication of regional oceanographic behaviour than the loca l SST record, The northeast monsoon signal in the coral delta(18)O dom inates the mean annual signal and shows the best correlation with the instrumental data sets. It appears that variations in the coral delta( 18)O are controlled mainly by variations in the intensity of surface w ater influx from the Indian Ocean to the Red Sea during the winter nor theast monsoon. Of particular significance is that the decadal time-sc ale variations in the coral skeletal delta(18)O are closely correlated with both the Indian Ocean SST and with variations in the Pacific-bas ed Southern Oscillation index, That is, isotopically light coral skele ton, indicating strong NE monsoon Red Sea inflow, correlates with peri ods of high Indian Ocean SST and with predominantly negative (El Nino) phases of the Southern Oscillation, The simultaneous nature of inter- decadal changes in Asian monsoon and ENSO behaviour suggest pan-Indo-P acific tropical climate reorganisation and evolution.