Sea level oscillations in Japan and China since the start of the 20th century and consequences for coastal management – Part 1: Japan

Sea level oscillations in Japan and China since the start of the 20th century and consequences for coastal management – Part 1: Japan

http://bit.ly/2s66ge4

Albert Parker

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https://doi.org/10.1016/j.ocecoaman.2018.12.031

Highlights

  • Japan has strong quasi-20 and quasi-60 years low frequencies sea level fluctuations.
  • These periodicities translate in specific length requirements of tide gauge records.
  • 1894/1906 to present, there is no sea level acceleration in the 5 long-term stations.
  • Those not affected by crustal movement (4 of 5) do not even show a rising trend.
  • Proper consideration of the natural oscillations should inform coastal planning.

Abstract

In Japan tide gauges are abundant, recording the sea levels since the end of the 19th century. Here I analyze the long-term tide gauges of Japan: the tide gauges of Oshoro, Wajima, Hosojima and Tonoura, that are affected to a lesser extent by crustal movement, and of Aburatsubo, which is more affected by crustal movement. Hosojima has an acceleration 1894 to 2018 of +0.0016 mm/yr2. Wajima has an acceleration 1894 to 2018 of +0.0046 mm/yr2. Oshoro has an acceleration 1906 to 2018 of −0.0058 mm/yr2. Tonoura has an acceleration 1894 to 1984 of −0.0446 mm/yr2. Aburatsubo, has an acceleration 1894 to 2018 of −0.0066 mm/yr2. There is no sign of any sea level acceleration around Japan since the start of the 20th century. The different tide gauges show low frequency (>10 years) oscillations of periodicity quasi-20 and quasi-60 years. The latter periodicity is the strongest in four cases out of five. As the sea levels have been oscillating, but not accelerating, in the long-term-trend tide gauges of Japan since the start of the 20th century, the same as all the other long-term-trend tide gauges of the world, it is increasingly unacceptable to base coastal management on alarmist prediction that are not supported by measurements.

And the Conclusion.

In three of the four long-term tide gauges of Japan, Oshoro, Wajima, Hamada, there is no sea level rise and there is no sea level acceleration. Hosojima has an acceleration 1894 to 2018 of +0.0016 mm/yr2. Wajima has an acceleration 1894 to 2018 of +0.0046 mm/yr2. Oshoro has an acceleration 1906 to 2018 of −0.0058 mm/yr2.

In the fourth term tide gauge of Japan, an apparent sea level rise and acceleration is only the result of the composite record obtained by coupling the long-term tide gauge record of Tonoura, of no acceleration and no sea level rise, with the short-term tide gauge record of Hamada II, sinking and rising at a much faster rate. Tonoura has an acceleration 1894 to 1984 of −0.0446 mm/yr2.

The other long-term tide gauge of Japan, Aburatsubo, which is significantly affected by crustal movement, has an acceleration 1894 to 2018 of −0.0066 mm/yr2.

There is therefore no sign of any sea level acceleration around Japan since the start of the 20th century.

All the long-term tide gauges considered show a clear multidecadal oscillation of periodicity quasi-60 years. This translate in the need of tide gauge records long enough to compute rates of rise (>60 years) and accelerations (>100 years).

Ocean and coastal management should be based on reliable data for sea level rise and acceleration, not on alarmist speculation.

Read the full article here.

Superforest,Climate Change

via Watts Up With That? http://bit.ly/1Viafi3

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