Precipitation structures and atmospheric waves over the tropical ocean

Propagating disturbances in the tropical atmosphere which exhibit characteristics of linear equatorial waves have been shown to be “coupled” to convection. Considering the difference in dynamical characteristics between these equatorial wave types, it follows that the “coupled” convective dynamics might differ depending on wave type. Rain events spanning three years at Kwajalein Atoll, RMI, were classified by associated wave type (i.e. Kelvin or mixed Rossby-gravity (MRG)) using space-time spectral-filtered outgoing longwave radiation (OLR). Contoured frequency by altitude diagrams (CFADs) of radar for the classified dates were compared between the two groups. Kelvin wave-associated rain days show a distinctly different vertical structure from MRG wave-associated rain days with a significant shift towards smaller reflectivity values at all heights. The mean rain-rate for Kelvin wave-associated storms was also higher than the MRG events despite a shift towards smaller reflectivity values. Our observational result suggests that convective dynamics differs significantly between rainstorms associated with these two different tropical atmospheric wave types.