Journal of Tropical Oceanography ›› 2024, Vol. 43 ›› Issue (5): 1-16.doi: 10.11978/2023150CSTR: 32234.14.2023150

• Marine Hydrology •     Next Articles

Impact of Atlantic Multidecadal Oscillation on interannual relationship between ENSO and early summer marine heatwaves in the Western Pacific*

YUAN Yu1,2(), XU Haiming1,2(), MA Jing1,2, ZHANG Tong1,2   

  1. 1. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CICFEMD) / Key Laboratory of Meteorological Disaster, Ministry of Education (KLME) / Joint International Research Laboratory of Climate and Environment Change (ILCEC), Nanjing University of Information Science and Technology, Nanjing 210044, China
    2. College of Atmospheric Science, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • Received:2023-10-16 Revised:2023-12-14 Online:2024-09-10 Published:2024-10-10
  • Supported by:
    National Natural Science Foundation of China(42192562); National Natural Science Foundation of China(41975106)

Abstract:

Marine heatwaves are extreme high temperature events that occur on the oceans and have devastating impact of marine environment and ecosystems. Using the fifth generation of European centre for medium-range weather forecasts atmospheric reanalysis data (ERA5) and the Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST) dataset during the period of 1960-2020, and data from the North Atlantic idealized experiments performed with the CESM1 model, this study investigated the variation of the interannual relationship between the El Niño-Southern Oscillation (ENSO) and the following early summer marine heatwaves in the western Pacific, and the possible reasons for their decadal variation based on correlation, synthetic analysis and other statistical methods. The results are shown as follows. 1) The interdecadal relationship between the ENSO and the following early summer marine heatwaves months in the western Pacific displays a prominent decadal variation, which is modulated by the Atlantic Multidecadal Oscillation (AMO). A high correlation between the ENSO and the following early summer marine heatwaves in the western Pacific appears during the positive AMO phase, while no significant correlation is found during the negative AMO phase. 2) AMO mainly affects the response of atmospheric circulation in the Northwest Pacific by modulating ENSO amplitude, thereby affecting the relationship between the ENSO and the following early summer marine heatwaves in the western Pacific. During the negative (positive) AMO phases, the Northwest Pacific anomalous anticyclone/cyclone appears strong (weak), and its position shifts toward east (west) in the following early summer, due to the relatively strong (weak) ENSO events through strong (weak) wind-evaporation-SST positive feedback mechanism. Thus, the position and intensity of anomalous anticyclones/cyclones led to significant differences in the distribution of early summer marine heatwaves in the western Pacific between the positive and negative AMO phase.

Key words: early summer marine heatwaves, western Pacific, ENSO, AMO, Northwest Pacific anomalous anticyclone/cyclone