Preprints
https://doi.org/10.5194/acpd-14-1349-2014
https://doi.org/10.5194/acpd-14-1349-2014
17 Jan 2014
 | 17 Jan 2014
Status: this preprint was under review for the journal ACP but the revision was not accepted.

Where do the air masses between double tropopauses come from?

A. C. Parracho, C. A. F. Marques, and J. M. Castanheira

Abstract. An analysis of the origin of air masses that end up between double tropopauses (DT) in the subtropics and midlatitudes is presented. The double tropopauses were diagnosed in the ERA-Interim reanalysis (1979–2010), and the origin of air masses was analysed using the Lagrangian model FLEXPART.

Different processes for the formation of double tropopauses (DT) have been suggested in the literature. Some studies have suggested that double tropopauses may occur as a response to the vertical profile of adiabatic heating, due to the residual meridional circulation, while others have put forward contradicting explanations. Whereas some studies have suggested that double tropopauses result from poleward excursions of the tropical tropopause over the extratropical one, others have argued that DTs develop in baroclinic unstable processes involving transport of air from high latitudes.

In some regions, the DT structure has a semipermanent character which cannot be explained by excursions of the tropical tropopause alone. However, the results presented in this paper confirm that processes involving excursions of the tropical tropopause over the extratropical tropopause, which are therefore accompanied by intrusions of air from the tropical troposphere into the lower extratropical stratosphere, make a significant contribution for the occurrence of DTs in the subtropics and midlatitudes. Specifically, it is shown that the air between double tropopauses comes from equatorward regions, and has a higher percentage of tropospheric particles and a lower mean potential vorticity.

A. C. Parracho, C. A. F. Marques, and J. M. Castanheira
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
A. C. Parracho, C. A. F. Marques, and J. M. Castanheira
A. C. Parracho, C. A. F. Marques, and J. M. Castanheira

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