Ozone Variability in the Midlatitude Upper Troposphere and Lower Stratosphere Diagnosed from a Monthly SAGE II Climatology Relative to the Tropopause

摘要

[1] A midlatitude (25°–65°) monthly zonal median ozone climatology in the upper troposphere and lower stratosphere (UTLS), from 8 to 20 km with a 0.5-km vertical resolution and a 5° latitudinal resolution, is developed on the basis of version 6.2 (V6.2) ozone profile retrievals from the Stratospheric Aerosol and Gas Experiment (SAGE) II measurements from October 1984 to August 2005. To avoid mixing of the tropospheric ozone data with stratospheric values, the thermal tropopause height is used as a base altitude for developing the climatology (the monthly mean tropopause height has been added back to the climatological profile). This feature of the developed ozone climatology, together with the near global SAGE II data coverage, complements the existing ozone climatologies in the midlatitude UTLS. In addition to using this climatology to describe hemispheric differences in the UTLS ozone (the primary purpose of this paper), the database can also be used to initialize atmospheric chemistry-transport models or for satellite data retrieval. The specific new findings include (1) the differences in the vertical structure of monthly ozone evolution across the tropopause between the NH and the SH, (2) all year bimodal probability distribution functions (PDFs) of the tropopause ozone, and (3) the annual cycle of the tropopause ozone PDF with increasing (decreasing) presence of ozone-rich air leading to tropopause ozone enhancements (reductions) during spring and early summer (fall and winter). The derived climatology is shown to be consistent with the ozonesonde climatologies of Logan (1985, 1999a) in many respects, including ozone seasonal cycle at the tropopause and in the UT, the broad summer ozone maximum in the northern UT, and non-Gaussian ozone PDFs at the tropopause. This consistency strengthens the confidence in SAGE II satellite ozone remote sensing in the UTLS. The derived SAGE II midlatitude ozone climatology is compared to ozonesonde measurements at Hohenpeissenberg (47.4°N, 11°E), Germany, and Lauder (45°S, 169.7°E), New Zealand. The monthly ozone climatology data are provided as auxiliary material to this report.