Chapter I Intro & Objectives - SPREP

PHOENIX ISLANDS PROTECTED AREA MANAGEMENT PLAN
Chapter III. Background, 1. Physical Setting of the Islands
Draft 1 March 2007
Stoddar and Fosberg (1994) noting the number of paleohoa (ancient lagoon passages) in
Abariringa (Canton), Enderbury, and Orona (Hull) speculated that hurricanes must have been
more frequent in the Central Pacific in the mid-Holocene period.
The Southern Oscillation refers to variations in air pressure between Indonesia and the South
Pacific (Nunn 1994). When air pressure was anomalously high in one area, it was
anomalously low in the other. The measure for this variation is called the Southern
Oscillation Index (SOI). Extremes of SOI values are associated with extreme weather
conditions such as droughts in the central Pacific (including the Phoenix Islands), and
changes in ocean currents and temperatures.
Nunn (1994) illustrated average annual pressure (mbar) at sea level in January and July based
on observations between 1900 and 1939 (see Figure III-1.35 below). The Phoenix Islands
atmospheric pressure of between 1006 mbars in January to 1009 mbars in July.
Figure III-1.35. Average annual atmospheric pressure (mbar) at sea level in January
and July for the central Pacific, including the Phoenix Islands.
(source: Nunn 1994)
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