Boreal summer intraseasonal oscillations in the MJO skeleton model with observation-based forcing |
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Institution: | 1. Université de Lille 1 - Sciences et Technologies, Polytech’Lille, and Laboratoire de Mécanique de Lille (LML), Cité Scientifique, 59655 Villeneuve d’Ascq, France;2. LabReo, Department of Mechanical Engineering, Universidade Federal do Espírito Santo, Avenida Fernando Ferrari, 514, Goiabeiras, 29075-910, ES, Brazil |
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Abstract: | The Madden-Julian oscillation (MJO) skeleton model is a low-order model for intraseasonal oscillations that, in an extended form, includes off-equatorial and antisymmetric components. Previous studies of this extended model have used an idealized background state and forcing terms. In the current study, observation-based estimates of these forcing terms and background state are used. Linear solutions to the extended model with this observation-based forcing consist of both equatorially-symmetric convective events and events with a meridional tilt reminiscent of composites of the boreal summer intraseasonal oscillation (BSISO) in observational studies. Solutions to a nonlinear stochastic form of the model exhibit realistic precipitation mean and variance and intraseasonal variability throughout much of the tropics. These solutions contain several types of events, including meridionally-tilted convective activity that moves both northward and eastward. Solutions to both forms of the model also indicate that this BSISO-like convective activity is coupled to activity over the eastern Pacific. A discussion of these features and their agreement with previous observational studies of the BSISO is given. |
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Keywords: | Boreal summer intraseasonal oscillation MJO skeleton model |
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