Precursor Signals and Processes Associated with MJO Initiation over the Tropical Indian Ocean
Precursor Signals and Processes Associated with MJO Initiation over the Tropical Indian Ocean
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DOI：
10.1175/jcli-d-12-00113.1
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发表时间：
2013-01
影响因子：
4.9
通讯作者：
Chongbo Zhao;Tim Li;Tianjun Zhou
中科院分区：
文献类型：
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作者：
Chongbo Zhao;Tim Li;Tianjun Zhou
通过对1982-2001年40 a ECMWF再分析(ERA-40)资料的诊断分析，研究了北半球冬季与Madden-Julian振荡(MJO)相关的对流启动前兆信号。西赤道印度洋(WIO)是MJO启动的关键区域。对流爆发前5-10天，对流层低层比湿度和温度显著增加。对流层低层水(热)收支的诊断表明，水汽(温度)的增加主要是由MJO气流对平均比湿(温度)的水平平流引起的。异常气流主要由东印度洋上空前一次抑制位相MJO的下游Rossby波响应所决定，而上游Kelvin波对前一次东向传播的MJO的响应则主要由前一次东向传播的Kelvin波响应决定。
AbstractThe precursor signals of convection initiation associated with the Madden–Julian oscillation (MJO) in boreal winter were investigated through the diagnosis of the 40-yr ECMWF Re-Analysis (ERA-40) data for the period 1982–2001. The western equatorial Indian Ocean (WIO) is a key region of the MJO initiation. A marked increase of specific humidity and temperature in the lower troposphere appears 5–10 days prior to the convection initiation. The increased moisture and temperature cause a convectively more unstable stratification, leading to the onset of convection.A diagnosis of lower-tropospheric moisture (heat) budgets shows that the moisture (temperature) increase is caused primarily by the horizontal advection of the mean specific humidity (temperature) by the MJO flow. The anomalous flow is primarily determined by the downstream Rossby wave response to a preceding suppressed-phase MJO over the eastern Indian Ocean, whereas the upstream Kelvin wave response to the previous eastward-propagating con...