The Interaction of the Madden-Julian Oscillation and the Maritime Continent in a GCM
Primary Author: Inness, Peter Additional Authors: Julia Slingo
The Interaction of the Madden-Julian Oscillation and the Maritime Continent in a GCM
Peter Inness and Julia Slingo
National Centre for Atmospheric Science - Climate Division, University of Reading
As the Madden-Julian Oscillation (MJO) passes over the islands of the Maritime Continent it is observed to weaken somewhat before reinvigorating over the West Pacific. However, studies with the HadCM3 coupled GCM showed that the MJO tends to die out altogether over this region, with very few cases of active MJO convection propagating from the Indian Ocean to the West Pacific. In this study, the effect of the topography of the Maritime Continent islands acting to disrupt the low level wind and pressure signal associated with the MJO is investigated. An idealised modelling framework is used in which an eastward propagating SST anomaly dipole is used to force organised convection which resembles the MJO. It is found that, although the island topography in the GCM is very much lower than in reality, it has a disproportionately large impact on the low level winds and pressure trough to the east of the convective maximum of the MJO. In particular the representation of Summatra as a single gridpoint wide, north-south oriented barrier seems to be central to the killing off of the MJO as it passes over the region in this GCM.
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