Characteristics of 3–4- and 6–8-Day Period Disturbances Observed over the Tropical Indian Ocean
Characteristics of 3–4- and 6–8-Day Period Disturbances Observed over the Tropical Indian Ocean
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DOI：
10.1175/2010mwr3469.1
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发表时间：
2010-11
影响因子：
3.2
通讯作者：
K. Yasunaga;K. Yoneyama;Q. Moteki;M. Fujita;Y. Takayabu;J. Suzuki;T. Ushiyama;B. Mapes
中科院分区：
文献类型：
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作者：
K. Yasunaga;K. Yoneyama;Q. Moteki;M. Fujita;Y. Takayabu;J. Suzuki;T. Ushiyama;B. Mapes
摘要实地观测活动[即，2006年12月至12月，在赤道印度洋中部上空进行了米拉伊号印度洋巡航考察，以研究MJO对流的发生。在MISMO期间，大规模有组织的对流伴随着弱的马登-朱利安振荡（MJO）爆发，并观察到其他一些显著的变化。水汽和降水资料显示，与纬向风场变化相关的周期变化明显，为3-4天周期。再分析数据中中层的过滤后的异常[即，日本气象厅（JMA）的气候资料同化系统（JCDAS）]显示了向西的相速度，其结构与Rossby-重力混合波相一致。估计的等效深度是几十米，典型的对流耦合波。在MISMO多雨的部分（11月16-26日），3-4天的波动在对流层低层和中层是连贯的，而在11月上旬不太活跃的时期，中层扰动波动出现较少。
Abstract A field observational campaign [i.e., the Mirai Indian Ocean cruise for the Study of the MJO-convection Onset (MISMO)] was conducted over the central equatorial Indian Ocean in October–December 2006. During MISMO, large-scale organized convection associated with a weak Madden–Julian oscillation (MJO) broke out, and some other notable variations were observed. Water vapor and precipitation data show a prominent 3–4-day-period cycle associated with meridional wind υ variations. Filtered υ anomalies at midlevels in reanalysis data [i.e., the Japan Meteorological Agency (JMA) Climate Data Assimilation System (JCDAS)] show westward phase velocities, and the structure is consistent with mixed Rossby–gravity waves. Estimated equivalent depths are a few tens of meters, typical of convectively coupled waves. In the more rainy part of MISMO (16–26 November), the 3–4-day waves were coherent through the lower and midtroposphere, while in the less active early November period midlevel υ fluctuations appear le...