King tides in June

Some of the highest predicted tides of the year were experienced towards the end of June. In Kosrae high tide levels over 7 feet were predicted during the early hours of Monday 24th and Tuesday 25th June. Fortunately there doesn’t appear to have been any significant inundation.

The latest Pacific ENSO Update newsletter has some further information on what caused these high (king) tides. This is what they had to say:

On 25 June (the day of that month’s full moon), and for a day or two before and after, the high tides were unusually high across Micronesia. On Majuro, they contributed to damaging inundation. Elsewhere, abnormally high tides were observed but did not cause any significant inundation or damage. These high-est of high tides of the year are locally referred to as King tides. “King tide” is not a scientific term, nor is it used in a scientific context. Use of the term originated in Australia, New Zealand and other Pacific nations to refer to an especially high tide that occurs only a few times per year.

Throughout Micronesia, the highest, and lowest tides of the year occur in June and again in December, based on the axial tilt of the earth. Another factor that can cause the highest of high tides to be even higher is the varying distance of the moon from Earth. When the moon is closest to the earth in its elliptical orbit (perigee) at the timing of the full or the new moon (syzygy), it can add about 15% to the height of the high tide. This phenomenon, resulting in a so-called “supermoon”, occurred during the full moon of 25 June 2013. The technical name is the perigee-syzygy of the Earth-Moon-Sun system. The term “supermoon” is not astronomical. It originated in modern astrology. The combined effect of the Sun and Moon on Earth’s oceans and tides, is greatest when the moon is either new or full. On 25 June 2013, everything came together to produce King tides in Micronesia: the moon was full, it was a “supermoon”, the tides were at their seasonal peak, and the mean sea level was elevated by about half-a-foot by persistently strong trade winds.

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