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contributor authorYasunaga, Kazuaki
contributor authorYoneyama, Kunio
contributor authorMoteki, Qoosaku
contributor authorFujita, Mikiko
contributor authorTakayabu, Yukari N.
contributor authorSuzuki, Junko
contributor authorUshiyama, Tomoki
contributor authorMapes, Brian
date accessioned2017-06-09T16:38:20Z
date available2017-06-09T16:38:20Z
date copyright2010/11/01
date issued2010
identifier issn0027-0644
identifier otherams-71387.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4213273
description abstractA 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 ? variations. Filtered ? 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 ? fluctuations appear less connected to those at the surface. SST diurnal variations were enhanced in light-wind and clear conditions. These coincided with westerly anomalies in prominent 6?8-day zonal wind variations with a deep nearly barotropic structure through the troposphere. Westward propagation and structure of time-filtered winds suggest n = 1 equatorial Rossby waves, but with estimated equivalent depth greater than is common for convectively coupled waves, although sheared background flow complicates the estimation somewhat. An ensemble reanalysis [i.e., the AGCM for the Earth Simulator (AFES) Local Ensemble Transform Kalman Filter (LETKF) Experimental Reanalysis (ALERA)] shows enhanced spread among the ensemble members in the zonal confluence phase of these deep Rossby waves, suggesting that assimilating them excites rapidly growing differences among ensemble members.
publisherAmerican Meteorological Society
titleCharacteristics of 3–4- and 6–8-Day Period Disturbances Observed over the Tropical Indian Ocean
typeJournal Paper
journal volume138
journal issue11
journal titleMonthly Weather Review
identifier doi10.1175/2010MWR3469.1
journal fristpage4158
journal lastpage4174
treeMonthly Weather Review:;2010:;volume( 138 ):;issue: 011
contenttypeFulltext


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