17:15 〜 18:45
[ACG33-P05] 波浪場の気候スケール変動の統計解析-平均場とENSOとの関連について-
キーワード：波浪、気候、大気海洋相互作用、エルニーニョ・南方振動
The energy driving ocean waves originates from the atmosphere and dissipates into the ocean during propagation. As the ocean covers 70% of the Earth's surface, understanding the role of ocean waves in transferring kinetic energy between the atmosphere and the ocean is crucial for comprehending the climate system.
This study involves constructing an original 64-year wave dataset, LWJ-55 (Long-term Wave-dataset simulated with JRA-55), using MRI-III (JMA's third-generation wave model) and conducting statistical analyses on it. The analyses include full-term intra-seasonal averaging and lagged-composite analysis on ENSO.
The full-term intra-seasonal average of the wave height field reveals a significant correlation with the surface wind field(Figure 1). This correlation is particularly evident in higher latitudes during winter in the northern hemisphere and throughout the year in the southern hemisphere, where strong westerly winds generate high waves. Additionally, the analysis indicates that swell height is elevated in specific equatorial zones, with its distribution not consistently aligning with either the wind field or the significant wave height field. Interestingly, zones with high significant wave heights correspond to areas where horizontal kinetic energy flux, driven by wave propagation, diverges. Conversely, regions characterized by low significant wave heights yet high swell heights correspond to flux convergence zones. These convergence zones also coincide with the convergence zones of surface winds, known as ITCZ (Intertropical Convergence Zone) and SPCZ (South Pacific Convergence Zone).
The lagged-composite analysis on ENSO reveals coherent anomalies in wind speed, significant wave height, and swell height on a global scale(Figure 2). However, in certain areas of the tropical Pacific, anomalies in wind speed and swell height display inverse correlations, moderating the anomalies in significant wave height. Furthermore, regions where kinetic energy flux converges in the tropics exhibit anomalies similar to those of the ITCZ and SPCZ, it intensifies during El Niño events and diminishes during La Niña events.
This study involves constructing an original 64-year wave dataset, LWJ-55 (Long-term Wave-dataset simulated with JRA-55), using MRI-III (JMA's third-generation wave model) and conducting statistical analyses on it. The analyses include full-term intra-seasonal averaging and lagged-composite analysis on ENSO.
The full-term intra-seasonal average of the wave height field reveals a significant correlation with the surface wind field(Figure 1). This correlation is particularly evident in higher latitudes during winter in the northern hemisphere and throughout the year in the southern hemisphere, where strong westerly winds generate high waves. Additionally, the analysis indicates that swell height is elevated in specific equatorial zones, with its distribution not consistently aligning with either the wind field or the significant wave height field. Interestingly, zones with high significant wave heights correspond to areas where horizontal kinetic energy flux, driven by wave propagation, diverges. Conversely, regions characterized by low significant wave heights yet high swell heights correspond to flux convergence zones. These convergence zones also coincide with the convergence zones of surface winds, known as ITCZ (Intertropical Convergence Zone) and SPCZ (South Pacific Convergence Zone).
The lagged-composite analysis on ENSO reveals coherent anomalies in wind speed, significant wave height, and swell height on a global scale(Figure 2). However, in certain areas of the tropical Pacific, anomalies in wind speed and swell height display inverse correlations, moderating the anomalies in significant wave height. Furthermore, regions where kinetic energy flux converges in the tropics exhibit anomalies similar to those of the ITCZ and SPCZ, it intensifies during El Niño events and diminishes during La Niña events.