Estimating the 27-day and 11-year solar cycle variations in tropical upper stratospheric ozone

• Published in: Journal of Geophysical Research: Atmospheres 2009-01, Vol.114 (D2), p.n/a
• Main Author: Fioletov, V. E.
• Format: Article
• Language: English
• Subjects: Amplitudes; Earth sciences; Earth, ocean, space; Estimates; Exact sciences and technology; Magnesium; Ozone; Proxy client servers; solar; Solar activity; Solar cycles; Solar flux; upper stratosphere
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2008JD010499

Spectral analysis of the solar backscatter ultraviolet (SBUV) satellite instrument ozone and solar flux time series was used to estimate the ozone response in the tropical upper stratosphere to the solar flux harmonics of the 27‐day Sun rotation cycle with periods of 9, 13.5, and 27 days. Solar UV flux at 205 nm, Mg II index, composite solar Lyman alpha, and 10.7 cm solar flux data sets were tested as proxies for the solar signal. The Mg II index has the highest coherency with tropical ozone in the upper stratosphere among all solar proxies. The analysis shows that during the periods of high solar activity, about half of the ozone variance for periods of 13.5 and 27 days near 40 km can be attributed to the fluctuations of the Mg II index. During the periods of low solar activity, the 27‐day signal is below the 90% statistical significance level, while the 13.5‐day signal is usually significant. Also, a 9‐day period can be seen in ozone data during the time of low solar activity. The ozone response to solar variations with a 27‐day period was used to estimate the 11‐year solar cycle amplitude in tropical ozone. Biases in individual SBUV instrument data were included as a part of the statistical model. In that case, the estimate from the 27‐day period minimum to maximum range of the 11‐year cycle is about 2%. This agrees with the data in layers 8–9 (38–43 km) derived from the SBUV data set. Below these layers, the amplitude of the 11‐year cycle is only about one third of the one estimated from the 27‐day cycle. Above these layers, the amplitude of the 11‐year cycle is larger than that estimated from the 27‐day cycle, but it is primarily due to the high amplitude of the 11‐year cycle in the Nimbus 7 SBUV data.