2.1
ENSO during the first half of the twentieth century: Evidence from a proxy record
Leslie M. Hartten, CIRES/Univ. of Colorado and NOAA/AL, Boulder, CO; and E. B. Buxton
Late in the nineteenth century, Sir Albert Ellis of New Zealand discovered that the rocks found on Nauru (0.26S, 165.55E) and Ocean (now Banaba) Islands (0.53S, 169.35E) contained large amounts of high-quality phosphate. Mining operations soon began. Phosphate mined on the islands was shipped out from ports located on the west side of the islands; these ports were closed to shipping during times of strong westerlies. Records kept by the British Phosphate Commission provide an almost 50-year monthly timeseries of when strong near-surface westerlies occurred at these two islands.
The number of days per year during which the ports were closed due to bad weather is highest (lowest) during years when the SOI was negative (positive). This is consistent with results from late twentieth century surface observations and analyses, which show that the annual frequency of westerly wind bursts is negatively correlated with the SOI. Results of a lagged correlation analysis between monthly values of the SOI and of port closings will be presented, as will a more modern analysis of the relationship between the SOI and strong equatorial westerlies. Patterns of variability seen in the historical proxy data will be compared to those seen in data from the later portion of the twentieth century.
Session 2, Observed Climate Variability and Change: Proxy Records (Parallel with Session 1)
Monday, 15 January 2001, 10:30 AM-2:45 PM
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