DOI: 10.25921/9f0t-kr79
title: NOAA/WDS Paleoclimatology - Ras Umm Sidd - del18O Data

description: A 245-year coral oxygen isotope record from the northern Red Sea (Ras Umm Sidd/Egypt, ~28N) in bimonthly resolution is presented. The mean annual coral d18O signal apparently reflects varying proportions of both sea surface temperature and d18Oseawater variability. In conjunction with instrumental observations of climate the coral record suggests for interannual and longer timescales that colder periods are accompanied by more arid conditions in the northern Red Sea but increased rainfall in the southeastern Mediterranean, whereas warmer periods are accompanied by decreased rainfall in the latter and less arid conditions in the northern Red Sea. A ~70-year oscillation of probably North Atlantic origin dominates the coral time series. Interannual to interdecadal variability is correlated with instrumental indices of the North Atlantic Oscillation (NAO), the El Nino-Southern Oscillation (ENSO), and North Pacific climate variability. The results suggest that these modes contributed consistently to Middle East climate variability since at least 1750, preferentially at a period of ~5.7 years.
description: Ras Umm Sidd bimonthly coral oxygen isotope data (coral core RUS-95). Notes on the data: File (Ras Umm Sidd d18O.txt.) includes columns for Year AD (bimonthly resolution: Jan-Feb, Mar-Apr, May-Jun, etc.) and coral d18O in per mil relative to the Vienna peedee belemnite (VPDB) reference standard. The coral core was collected in the end of November 1995 in the northern Red Sea at Ras Umm Sidd (27°0.9'N, 34°18.6'E) in the Ras Mohammed National Park near the southern tip of the Sinai Peninsula (Egypt), from a 2.6-m-high coral colony (Porites sp.) growing at a water depth of ~5.5 m. The average annual growth rate of the coral is 1 cm/year. The average sampling resolution for oxygen isotope analysis is more than 6 samples per year. Oxygen isotope analysis was performed on a Finnigan MAT 251 mass spectrometer coupled to an automated carbonate device at the stable isotope laboratory of the Department of Geosciences at Bremen University, Germany. Long-term reproducibility for d18O, deduced from replicate measurements of an internal carbonate standard, is better than ±0.07 per mil. The coral chronology is constructed by setting the maximum d18O value in a given year equal to mid-February (consistent with the climatological minimum in sea surface temperature) and assuming a constant coral growth rate between February of every year. Therefore we interpolated linearly between these fixed points for further age assignments. The resulting values were interpolated linearly to six equally spaced values per year, providing a bimonthly resolution. The strong seasonal cycle in d18O was used to count annual layers in the coral, supported by the consistent density banding pattern of low-density band creation during winter and high-density band creation during summer. The coral record extends from fall 1750 to fall 1995. We assigned an age model error of at least 2-3 months to the coral chronology. In addition, we assigned an age model error of ±1 year to the interval 1924-1783 and an additional ±1 year to 1782-1750. Therefore the chronology is assigned a cumulative age model error of less than ±3 years at the bottom of the core. More information on the Ras Umm Sidd coral oxygen isotope record can be found in the original reference.