Analysis of convectively coupled Kelvin waves in 21 WCRP CMIP3 models

Output from 21 global coupled models is analyzed for the existence and structure of convectively coupled Kelvin waves. Model data are obtained from the World Climate Research Program's (WCRP) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset. Data from the “Climate of the 20th Century Experiment” model runs (1961-2000) are analyzed.

Kelvin waves are isolated using a wavenumber-frequency spectral filtering technique, and composite structures are calculated via linear regression. The resulting 3-dimensional dynamical and thermodynamical wave structures are then compared to observations of convectively coupled Kelvin waves based on satellite and radiosonde data.

Results show that of the 21 models analyzed, only 8 contain realistic Kelvin wave precipitation spectra, and of these 8, only 3 have horizontal and vertical structures comparable to observations. Further analysis will investigate additional model output to gain insight into the model differences.