Based on the tropical rainfall measuring mission (TRMM)-measured rainfall and estimated outgoing longwave radiation (OLR) fields, it is found that 2007–08 Madden–Julian Oscillation (MJO07-08) went through blocking, splitting, and merging stages when it passed over the New Guinea Highlands (NGH). The TRMM-estimated OLR fields fail to capture detailed TRMM rainfall field and thus is not suitable to serve as proxy for rainfall, as also found in previous studies. The mechanism of orographic blocking is explained by strong orographic blocking on the incoming, low-Froude number, and moist flow, which belonged to the flow-around regime. This is evidenced by estimating the Froude number by upstream soundings. The strong blocking forced the flow to go around the mountains on NGH, leading to the splitting of flow and MJO precipitating system and the merging at the southeast tip of New Guinea. Orographic, MJO, and cyclone clouds were shown in both observed and model-simulated results. The major differences of the model-simulated and TRMM-measured precipitation are as follows: (a) the model-simulated rainfall area is much larger than that covered by the observed rainfall and (b) even though they both show comparable maximum rainfall rate, the rainfall estimated by TRMM reveals more localized rainfall spots, which is unexpected since the WRF simulation uses a relatively fine resolution (5 km). In summary, during the blocking stage, the mountains have slowed down the MJO propagation and increased the rainfall amount upstream of the local mountains, while during the splitting and merging stages, the mountains have made significant impacts on the MJO rainfall distribution.

中文翻译：

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地形对传播和降雨变化的影响与 2007-08 马登-朱利安振荡 (MJO) 越过新几内亚高地有关

基于热带降雨测量任务 (TRMM) - 测量的降雨和估计的出射长波辐射 (OLR) 场，发现 2007-08 马登-朱利安振荡 (MJO07-08) 在发生时经历了阻塞、分裂和合并阶段。越过新几内亚高地 (NGH)。TRMM 估计的 OLR 场无法捕获详细的 TRMM 降雨场，因此不适合作为降雨的代理，这在之前的研究中也有发现。地形阻塞的机制可以用对来流、低弗劳德数和湿流的强地形阻塞来解释，属于绕流机制。通过上游探测估计弗劳德数证明了这一点。强烈的阻塞迫使水流在 NGH 上绕山而行，导致新几内亚东南端水流和 MJO 沉淀系统的分裂和合并。观测结果和模型模拟结果均显示了地形、MJO 和旋风云。模式模拟和TRMM测量的降水的主要区别如下：（a）模式模拟的降雨面积远大于观测降雨覆盖的面积；（b）尽管它们都显示出可比的最大降雨率， TRMM 估计的降雨量显示出更多的局部降雨点，这是出乎意料的，因为 WRF 模拟使用了相对精细的分辨率（5 公里）。综上所述，在阻塞阶段，山区减缓了 MJO 的传播，增加了当地山区上游的降雨量，而在分裂和合并阶段，