17:15 〜 19:15
[ACG43-P01] Similarities and Differences in the Phase Transitions of Atlantic Niño and El Niño
キーワード：アトランティックニーニョ、熱帯大西洋、大気海洋相互作用
The Atlantic Niño and Niña are characterized by anomalous sea water temperature (SWT) anomalies along the Gulf of Guinea sector especially in the tropical region with twin peaks occurring in summer or winter in the Northern Hemisphere. The characteristics of Atlantic Niño/Niña is similar to those of the El Niño/La Niña, in which the ocean waves in the sub-surface layer play a crucial role in the transition between the opposite phases. However, the physical processes that are responsible for the emergence of the Atlantic Niño/Niña remain unclear because of the inherent strong seasonal cycles in the tropical Atlantic Ocean. Thus, we examined the spatio-temporal structure of the Atlantic Niño/Niña from perspective of the propagation of the equatorial coupled atmosphere-ocean waves.
The Atlantic Niño and Niña can be categorized into two types, one peaking in summer and the other in winter, which have different characteristics. Climatically, a decrease of SWT is observable in the eastern Atlantic around June due to the eastward propagation of cold Kelvin waves. However, if this propagation is hindered for some reason, warming occurs in the eastern Atlantic, producing the Atlantic Niño. In the winter Niño cases, the equatorial warm Kelvin waves are main contributor to its development , which is followed by the westward propagation of the warm Rossby waves off the equator. Interestingly, the contribution of seasonal ocean wave is limited in the winter Niño. The reverse is almost true for the Atlantic Niña. On the day of the presentation, we further introduce how the seasonal cycles are generated, from the perspective of the atmosphere-ocean coupled system in the Atlantic Ocean and its surrounding continents.
The Atlantic Niño and Niña can be categorized into two types, one peaking in summer and the other in winter, which have different characteristics. Climatically, a decrease of SWT is observable in the eastern Atlantic around June due to the eastward propagation of cold Kelvin waves. However, if this propagation is hindered for some reason, warming occurs in the eastern Atlantic, producing the Atlantic Niño. In the winter Niño cases, the equatorial warm Kelvin waves are main contributor to its development , which is followed by the westward propagation of the warm Rossby waves off the equator. Interestingly, the contribution of seasonal ocean wave is limited in the winter Niño. The reverse is almost true for the Atlantic Niña. On the day of the presentation, we further introduce how the seasonal cycles are generated, from the perspective of the atmosphere-ocean coupled system in the Atlantic Ocean and its surrounding continents.