High frequency coupling between the tropical upper ocean and atmosphere at diurnal time scales is being recognised to be important for the behaviour of large scale climate modes such as the Madden Julian Oscillation (MJO). Sea surface temperature (SST) variability in the Eastern Indian Ocean warm pool and on the Northwest Shelf of Australia is strongly influenced by the MJO activity. In this study, we use the hourly Himawari-8 geostationary satellite SST data to understand the modulation of the amplitude of SST diurnal variations in the region by the MJO during two austral summer seasons of 2015–16 and 2016–17. The high temporal and spatial resolutions of the Himawari-8 SST data are able to capture the temporal and spatial variability of diurnal SST amplitude. Our results show that the MJO onset (active phase) is preceded by strong diurnal SST variations during the MJO suppressed phase. The amplitudes of the SST diurnal variations are mainly modulated by surface wind variability in the region, as denoted by their spatial and temporal correlations. The very strong El Niño event in 2015–16 may have significantly weakened the MJO activities in the region, resulting in prolonged MJO suppressed phase, high diurnal SST variation and mean SST. This study provides background knowledge for future research on how the diurnal SST variation in the region may influence the progression of the MJO events.

人们已经认识到，热带的上层海洋与大气在昼夜时间尺度之间的高频耦合对于诸如Madden Julian涛动（MJO）之类的大规模气候模式的行为很重要。东印度洋暖池和澳大利亚西北大陆架的海表温度（SST）变异性受MJO活动的强烈影响。在这项研究中，我们使用每小时的Himawari-8对地静止卫星SST数据来了解MJO在2015-16和2016-17的两个夏季南方季节对区域SST昼夜变化幅度的调制。Himawari-8 SST数据的高时空分辨率能够捕获日SST振幅的时空变化。我们的结果表明，在MJO抑制阶段，MJO发作（活动期）之前存在强烈的昼夜SST变化。SST日变化的幅度主要由该地区的表面风变率调制，如它们的空间和时间相关性所示。2015-16年度非常强烈的厄尔尼诺事件可能已大大削弱了该地区的MJO活动，导致MJO抑制期延长，昼夜SST变化和平均SST升高。这项研究为该区域日SST的变化如何影响MJO事件的进展提供了背景知识，可用于未来的研究。2015-16年度非常强烈的厄尔尼诺事件可能已大大削弱了该地区的MJO活动，导致MJO抑制期延长，昼夜SST变化和平均SST升高。这项研究为该区域日SST的变化如何影响MJO事件的进展提供了背景知识，可用于未来的研究。2015-16年度非常强烈的厄尔尼诺事件可能已大大削弱了该地区的MJO活动，导致MJO抑制期延长，昼夜SST变化和平均SST升高。这项研究为该区域日SST的变化如何影响MJO事件的进展提供了背景知识，可用于未来的研究。