Weather on Oceans
The Pacific Ocean
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Winds and currents in the Pacific flow predominantly from East to West. Above the equator Pacific Ocean trade winds blow from the northeast. Below the equator they blow from the southeast. By taking advantage of the different (north and south) directions of the east-flowing winds, traditional Polynesian navigators could sail eastward ( into the wind) north of the equator and let the winds and currents push them southwest once south of the equator. In this way Polynesians could navigate the 2,250 nautical miles from Hawai'i to Tahiti, by taking advantage of the different orientation of the prevailing trade winds north and south of the equator.
The more difficult journey for Polynesians was the one from southernmost Polynesia (New Zealand/Aotearoa) north to Fiji. While the same wind and current direction prevails throughout the year--there is a regular disruption of this pattern by summer monsoons in the region between New Guinea and Fiji. During the winter winds blow in the opposite direction from the prevailing one. These opposite (west flowing) winds last longer during major El Niño events which usually begins with the weakening of the usual trade winds. Captain Cook reported that a Polynesian navigator told him that they waited for the summer monsoons to make this voyage north.
The second difficult stage of the journey from southern to northern Polynesia occurred in traveling east from Fiji to Tahiti. Using the low pressure troughs from sub-tropical depressions during the summer monsoon period, Polynesian canoes could navigate from Samoa (north of Fiji) to the Society Islands, then Rarotonga and Tahiti.
* One of three large divisions of Pacific peoples. French explorer Charles de Brosses created the name "Polynesia" in 1756. Another French explorer, de Surville, used Micronesia and Melanesia in 1828.
