Critical Roles of the Stratiform Rainfall in Sustaining the Madden–Julian Oscillation: GCM Experiments*
Critical Roles of the Stratiform Rainfall in Sustaining the Madden–Julian Oscillation: GCM Experiments*
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DOI：
10.1175/2009jcli2610.1
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发表时间：
2009-07
影响因子：
4.9
通讯作者：
Xiouhua Fu;Bin Wang
中科院分区：
文献类型：
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作者：
Xiouhua Fu;Bin Wang
本文在ECHAM4大气环流模式及其耦合模式中评估了层状降雨(即大尺度降雨)对Madden-Julian振荡(MJO)发展和维持的影响。为了检验模式MJO将如何随层状比例(层状与总降雨量的比率)的变化而变化，在天气预报设置下进行了一系列敏感性试验，并使用了三个20年的自由积分。在这些实验中，作为层状云水补给的深/浅对流的减速速率被修改，从而导致层状降水的显著变化。预报试验和长期自由积分均表明，只有当模式产生相当大比例的层状降水(≥为30%)时，才能维持较强的MJO。当层状降水所占比例变小时，模式中的热带降水以细雨状暴雨为主。
Abstract This study assesses the impact of stratiform rainfall (i.e., large-scale rainfall) in the development and maintenance of the Madden–Julian oscillation (MJO) in a contemporary general circulation model: ECHAM4 AGCM and its coupled version. To examine how the model MJO would change as the stratiform proportion (the ratio of the stratiform versus total rainfall) varies, a suite of sensitivity experiments has been carried out under a weather forecast setting and with three 20-yr free integrations. In these experiments, the detrainment rates of deep/shallow convections that function as a water supply to stratiform clouds were modified, which results in significant changes of stratiform rainfall. Both the forecast experiments and long-term free integrations indicate that only when the model produces a significant proportion (≥30%) of stratiform rainfall can a robust MJO be sustained. When the stratiform rainfall proportion becomes small, the tropical rainfall in the model is dominated by drizzle-like r...