Tropopause folding at satellite‐observed spatial gradients: 1. Verification of an empirical relationship

Abstract

Tropopause folding, a mechanism for stratosphere/troposphere exchange (STE), can be detected indirectly from strong spatial gradients in two satellite‐derived products that are primarily sensitive to tropopause height: the altered water vapor product, developed from the GOES water vapor channel; and the Total Ozone Mapping Spectrometer level 2 total ozone product. The images were preprocessed with an optimized smoothing algorithm that filtered out gradients at spatial scales of less than ∼30 km. This removed jagged, fine‐scale edges in the moisture fields and helped emphasize upper tropospheric air mass boundaries and dry air “streamers,” which are both associated with STE. In the verification data set, 13 out of 14 tropopause folds identified by an airborne lidar were correctly distinguished by the technique with no false positives. These results have been applied in an empirical model over the midlatitudes to predict spatial and temporal patterns in tropopause folding.