Observed radar reflectivity in convectively coupled Kelvin and mixed Rossby-gravity waves

摘要

Propagating disturbances in the tropical atmosphere exhibiting characteristics of linear equatorial waves have been shown to be "coupled'' to convection. In some cases, a rain event at a specific location can be associated with a particular wave of sufficiently large amplitude. Rain events spanning three years at Kwajalein Atoll, Republic of the Marshall Islands, 8.72 degrees N 167.73 degrees E, are 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. The Kelvin wave accumulated CFAD has a distribution shifted to lower reflectivities compared to MRG suggesting that Kelvin storms likely contain a larger fraction of stratiform to convective area compared to MRG storms.