A comparison of different metrics for analyzing the troposphere/stratosphere transitions using high-resolution ozonesondes

In recent years, NOAA Earth System Research Laboratories (ESRL) have been launching very high quality and high resolution ozonesondes from eight sites across the globe: Antarctica; Greenland; American Samoa; Fiji; and several sites in USA (Alabama, California, Colorado and Hawai'i). These locations collectively cover the tropics, mid-latitudes and polar regions. The balloons provide in-situ measurements approximately every second throughout their vertical ascent and descent in the troposphere, tropopause and stratosphere (up to ~30-35 km altitude) with readings of: pressure; temperature; water vapor; ozone; horizontal wind speed and direction; and vertical ascent and descent velocity.

This unique high quality and publicly archived dataset allows direct inter-comparisons between various new and old techniques for analyzing the troposphere/stratosphere transitions that were not previously possible. With this in mind, we have analyzed one complete year (2016) of ozonesonde data from these eight locations in terms of several widely-used definitions of the tropopause, as well as some new definitions. We find a surprising cohesiveness between many of the independent definitions of the tropopause that does not appear to have been properly recognized until now. These definitions appear to hold over all eight locations – from the tropics to the poles – for all seasons.

We discuss the implications of these new results for our understanding of the interrelationships between the upper troposphere, tropopause and stratosphere.