Interactions Between Local Atmospheric Vertical Structures and the Madden-Julian Oscillation

A fundamental yet poorly understood aspect of the Madden-Julian Oscillation (MJO) is the interaction among the local atmospheric state, cumulus and mesoscale convection, and the large-scale flow field. These interactions can be partly assessed through the use of data sets derived from in situ observations and remotely sensed measurements. In this study, we use a host of Indian Ocean radiosonde data sets to explore the mean and time-evolving components of the local atmospheric vertical structure and its relation to organized MJO convection during all stages of its life cycle. The Indian Ocean is an area of relatively sparse coverage of measured data. The details of the mean thermodynamic profiles within the Indian Ocean region and how they may differ from those in the Pacific have yet to be closely examined and so will be addressed here. We survey long-term daily vertical profiles from the Integrated Global Radiosonde Archive (IGRA), sub-daily soundings from recent field experiments within the Indo-Pacific region including MISMO and DYNAMO, and satellite-based estimates of outgoing longwave radiation, column moisture, and precipitation. Our approach links large-scale MJO convection, as defined by the Wheeler-Hendon MJO index and other filtered convective signals, to the local atmospheric states as a way of assessing the impact of moisture on the initiation and maintenance of the MJO.