PUBLICATION HIGHLIGHT: Influences of the MJO on the space-time organization of tropical convection

Photo: Eduardo Jaeger courtesy
Photo: Eduardo Jaeger courtesy

The Madden and Julian Oscillation (MJO) is a large-scale pattern of tropical rainfall with a period of about 40 days, mainly over the tropical Indo-Pacific Region, which has worldwide impacts. In a new study published in the Journal of Geophysical Research – Atmospheres, researchers from ESRL’s Physical Sciences Division, CIRES, and the University of Hawaii investigate how the MJO interacts with daily-to-weekly rainfall variability and intensity and how the MJO impacts globally integrated rainfall.

The researchers find that while tropical convection is intensified where the MJO is active, it does not significantly impact the behavior of rainfall on shorter time scales. Particular types of large-scale tropical disturbances are not more likely to develop where the MJO is most active, instead the MJO enhances the overall activity of existing disturbances. As a result, the MJO changes the distribution of tropical rainfall, without increasing its total amounts.

Since current operational forecast models still struggle to simulate the MJO, this study offers observational targets for model development. Improvements in the representation of the MJO in forecast models will lead to better forecasts of global weather on daily to climate scales, even outside the tropics, since the MJO has such a large influence on the global atmosphere.

Authors of Influences of the MJO on the space-time organization of tropical convection are Juliana Dias, Naoko Sakaeda, and George Kiladis of the ESRL Physical Sciences Division, and Kazuyoshi Kikuchi of the University of Hawaii.