Imprint of the 11-year solar cycle in reanalyzed and radiosonde datasets: a spatial frequency analysis approach
Abstract
Oscillations in the period band of 10-12 years were globally analyzed by the pseudo-2D wavelet transform of reanalyzed (ERA-40 and NCEP/NCAR) and HadAT radiosonde series at several pressure levels. The results were obtained for the series of temperature, u and v wind velocities, ozone mass mixing ratios at pressure levels up to 10 hPa and temperature and height of the tropopause.
The study provides a detailed description of the oscillations' spatial distribution, together with mutual comparison of the reanalyzed datasets. The analysis is supplemented by a correlation study between the wavelet power spectra interval of the reanalyzed and radiosonde series.
For the temperature series, the study shows that the cycle is detected primarily in the tropics and subtropics; the details of the spatial patterns, however, differ significantly for the ERA-40 and NCEP/NCAR series. The analysis of the u and v velocities provides a new characterization of the longitudinal variability of the regions sensitive to solar forcing showing, e.g., preferences for Pacific Ocean areas at 100 hPa.
In the ozone mass mixing ratio fields, the oscillations are identified throughout hemispherically asymmetrical and vertically variable locations. The findings describe cycle spatial distribution in a new way and are in general agreement with other studies.
The analysis of the temperature and height of the tropopause showed that the regions where the cycle is detected are primarily found within tropical to middle latitudes, with pronounced longitudinal variability over the eastern Pacific Ocean.