Variability of Strato-Mesospheric O₃ Derived from Ground-Based Microwave Radiometry

Abstract

Comparison of strato-mesospheric 03 derived from ground-based microwave radiometry at Nagoya University with Umkehr measurements at Tsukuba by JMA (Japan Meteorological Agency) has been carried out for evaluation of microwave measurements. Good agreements between radio and Umkehr measurements have been found from Umkehr layer 6-9, which correspond to the pressure of 15.8-0.99hPa. Layer ozone amounts in layer 10 from microwave measurements show short term enrichment in winter with time scale of about a week, which are not observed by Umkehr measurements. The difference is due to the saturation effect inherent in Umkehr measurements. Fourier coefficients, up to the 2nd harmonic of the seasonal variations of nighttime and daytime mixing ratios, are given in tables for the pressure P=0.013, ..., 10hPa (log P=-1.875, ..., 1.000). QBO type variations of O3 in 1-0.1hPa range described in our earlier paper are due to the superposition of the short term enrichment. The short term enrichment was especially remarkable in 1992-1993 and 1994-1995. The short term enrichment does not correlate with temperature. A plausible cause of the enrichment will be vertical circulation anomalies as is the case of QBO variations in 03 at the lower-stratosphere, and in NO2 at the middle-stratosphere proposed by Randel and Wu (1996).