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Scientific question: Large-scale disturbances

The large-scale disturbances are discussed below:

Using equipment deployed for at least a year and data from observational networks, we will investigate the following:

  • Are there [oscillatory] convective activities in the two sites?  Climatological information suggest that the main MJO initiation takes place in the central IO from October to March, with the highest occurrence probability near the equator during October to January (Zhang & Dong 2004). The observations of the Dynamo Experiment were made during October to March 2012 (Yonayama et al. 2013), and the proposed winter and summer observations will add value to or complement those from Dynamo.
  • What are the generation mechanisms of northeastward propagating equatorial disturbances? One of the suggested mechanisms is related to a positive shortwave-radiation anomaly that develops north of equatorial convection region. It warms up the sea surface, increases the low-level convergence and moist static energy and destabilizes the atmosphere, thus leading to northward propagating equatorial convection. This and other plausible mechanisms will be pursued via observations.
  • Is there coherence between observations at our locations? We will analyze the surface pressure, temperatures and upper level moisture (mixing ratio and liquid water content).  What are the phase speed and wave length of propagating disturbances? Can we identify those using existing theoretical frameworks (e.g., westward-propagating Rossby waves, equatorial Kelvin waves)? The interest is not only eastward-propagating perturbations, but also the much slower, northward-propagating, component.
  • What are the time scales of convective activities – their initiation, maturation and decay?