Can stratospheric ozone measurements be used to quantify tropical width changes?

Abstract:

The stratospheric ozone column amount varies with latitude, in part due to the difference in tropopause height between the tropics and midlatitudes. This dependency of the ozone column on latitude has been exploited by several studies to identify tropical edge latitudes and to compute their trends over the past several decades. The global tropical widening trend estimate from this method is greater than 3° latitude decade^-1, a rate which is significantly larger than most other tropical widening estimates. In this study, we assess the robustness of the previously used total column ozone methodology for quantifying the tropical width by comparing the previously used method to a new gradient-based method of total column ozone. The two total column ozone edge latitude timeseries are then compared to a diagnostic based on the peak meridional gradient of ozone and water vapor concentration at several vertical levels in the upper troposphere and lower stratosphere region. This new tropical edge diagnostic is applied to two vertically resolved merged ozone and water vapor databases: the Binary DataBase of Profiles (BDBP) and the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) data set.