Convectively Coupled Equatorial Waves in Observations and Models

Synoptic activity in the tropics is often associated with waves which can be related to the preferred equatorially-trapped modes of the atmospheric circulation based on shallow water theory, but it is only in the last few years that it has become increasingly clear that these modes account for much of the organisation of tropical convection and of the development of tropical weather systems. The development and maintenance of equatorial waves is crucial for forecasting in the tropics, since these waves are the precursors for hurricanes and typhoons. The failure of present-day weather forecast and climate-prediction models to correctly capture the initiation of equatorial waves and their associated organised convection is largely due to inadequacies in the interaction of physics and dynamics, and is arguably one of the most fundamental errors in models used for weather and climate prediction.

This paper will introduce a new methodology for isolating convectively coupled equatorial waves in reanalysis and satellite data and show how it can be applied to the Hadley Centre's climate model to isolate fundamental difficulties in capturing organised tropical convection.