Association of double tropopause events with baroclinic waves

Abstract

We herein propose a method for identifying breaks in the subtropical tropopause as found in the ERA Interim reanalysis data. The method uses the identification of double tropopauses and allows the quantification of the extension of the overlap between the tropical and extratropical tropopauses. The correlations between the meridional extension of the superposition of tropopauses and the fields of geopotential, potential vorticity, or potential temperature, reveal baroclinic wave patterns. Similar wave patterns were also identified in the potential temperature fields derived from GPS radio occultation COSMIC data. The zonal propagation velocity of the anomalies in the meridional extension of the overlap was estimated using Hovmöller diagrams. The estimated zonal velocities suggest that the variability in the superposition of the tropopauses is associated with baroclinic Rossby wave patterns in the subtropical upper troposphere and lower stratosphere.