High‐resolution measurements and simulation of stratospheric and tropospheric intrusions in the vicinity of the polar jet stream

Abstract

Pronounced filamentation of tropospheric and stratospheric air masses was observed on a flight in the vicinity of the polar jet stream during the STREAM 1998 campaign in Timmins, Canada. High‐spatial resolution O 3 and H 2 O measurements showed highly variable structures for the investigated region. Reconstructing high‐resolution potential vorticity (PV) fields using the reverse‐domain‐filling (RDF) technique reproduce the in‐situ O 3 measurements qualitatively. Measurements and RDF results show the intrusion of stratospheric air penetrating deep into the troposphere. The observed intrusions occur on smaller horizontal scales than generally assumed for tropopause folding events. Moreover, fine‐scale structures of tropospheric air masses being lifted up into the stratosphere could be reconstructed by the RDF technique using the tropospheric tracer specific humidity in addition to the more conventional calculations for the stratospheric tracer PV.