A case study of the MJO event observed during January and February 2017 is conducted to understand its propagation through the Maritime Continent (MC) region. Ensemble cloud-permitting numerical simulations are performed to test the effects of the islands over MC on this MJO event. The control simulation reasonably captures the large-scale mean state, eastward propagation and diurnal cycle over islands of this MJO event. Sensitivity experiments are conducted to test the impact of topography, friction, and land-sea contrast on this MJO event. Eliminating the topography around the MC region leads to reduced precipitation over the islands while changes in eastward propagation are small. When friction is further removed, results are similar except that the low-level wind is stronger, and the MJO precipitation propagation is not essentially different. Land-sea contrast is further eliminated by replacing land with ocean, and the MJO is stronger and displays smoother eastward propagation. Diagnosis of moist static energy budget indicates that both the surface flux feedback and horizontal advection (especially the zonal advection) are greatly strengthened without land-sea contrast, which enhance the convection over the sea and facilitate the eastward propagation of the MJO.

对 2017 年 1 月和 2 月期间观察到的 MJO 事件进行了案例研究，以了解其在海洋大陆 (MC) 区域的传播。执行集合云允许数值模拟以测试 MC 上的岛屿对这次 MJO 事件的影响。控制模拟合理地捕捉到了本次 MJO 事件岛屿上空的大尺度平均状态、向东传播和昼夜循环。进行敏感性实验以测试地形、摩擦和海陆对比对这次 MJO 事件的影响。消除 MC 地区周围的地形会导致岛屿上的降水减少，而向东传播的变化很小。进一步去除摩擦后，结果相似，只是低层风更强，MJO降水传播没有本质区别。以海洋代替陆地，进一步消除了海陆反差，MJO更强，东向传播更顺畅。湿静态能量收支的诊断表明，在没有海陆对比的情况下，地表通量反馈和水平平流（尤其是纬向平流）都大大加强，这增强了海上对流，促进了 MJO 的向东传播。