Interannual variability and predictability of summertime significant wave heights in the western north pacific
Interannual variability and predictability of summertime significant wave heights in the western north pacific
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DOI：
10.1007/s10872-007-0022-9
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发表时间：
2007-04
影响因子：
2.3
通讯作者：
W. Sasaki;Hibiya Toshiyuki
中科院分区：
文献类型：
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作者：
W. Sasaki;Hibiya Toshiyuki
我们提出并验证了一个线性回归模型，该模型使我们能够预测北太平洋西部 (WNP) 夏季（6 月至 8 月）每月第 90 个百分位有效波高 (H90) 的平均值。 H90 最普遍的年际变化是通过对从 ERA-40 波再分析以及最佳插值 TOPEX/Poseidon (OITP) 波数据获得的 H90 应用经验正交函数分析来确定的。研究发现，H90的增加与WNP的气旋性环流相关，而WNP的气旋性环流又与Niño-3.4地区的温暖海温异常有关。由于 U10Ni 与 H90 的 PC1 密切相关，因此我们采用 5°N–15°N、130°E–160°E 区域平均纬向风距平 (U10N) 作为 H90 第一主成分 (PC1) 的预测因子。结果表明，从两个不同的波浪数据集获得的回归模型几乎相同。回归模型的可预测性根据 H90 和重建数据之间均方根 (rms) 误差的减少程度进行评估。研究发现，该预测器成功地将 ERA-40 波浪再分析的 rms 误差减少了 40%，将 10°N–25°N 纬度带内的 OITP 波浪数据的 rms 误差减少了 70%，但超过 0.3 m 的 rms 误差仍然存在，特别是在东海。
We propose and validate a linear regression model which enables us to predict the summer (June–August) mean of the monthly 90th percentile of significant wave heights (H90) in the western North Pacific (WNP). The most prevailing interannual variability of H90is identified by applying an Empirical Orthogonal Function analysis to H90obtained from the ERA-40 wave reanalysis as well as from the optimally interpolated TOPEX/Poseidon (OITP) wave data. It is found that the increase of H90is correlated with cyclonic circulation in the WNP which links with warm SST anomalies in the Niño-3.4 region. We adopt zonal wind anomaly averaged over the region 5°N–15°N, 130°E–160°E (U10N) as a predictor of the first principal component (PC1) of H90, since U10Nis closely correlated with the PC1 of H90. It is revealed that regression models obtained from two different wave datasets are nearly identical. The predictability of the regression model is assessed in terms of the reduction of the root-mean-square (rms) errors between H90and the reconstructed data. The predictor is found to be successful in reducing the rms errors by up to 40% for the ERA-40 wave reanalysis and by up to 70% for the OITP wave data within the latitudinal band 10°N–25°N, though rms errors exceeding 0.3 m still remain, particularly in the East China Sea.