Temporal evolution of S2 atmospheric tide as represented in reanalysis databases

Abstract

Temporal evolution of the semidiurnal component of the solar atmospheric tide (S2) has been assessed using six reanalysis databases. The motivation for this work is twofold: first, to validate the interpolation method commonly used (reanalysis data are generally available every 6 hours, just in S2 Nyquist frequency). And second, as the main forcing of the atmospheric tide is the UV absorption in the ozone layer and, to a lesser extent, the IR absorption by water in the troposphere, its amplitude could eventually be used as a proxy for these magnitudes. The main results of this study are: i) the usual interpolation method is basically correct to evaluate mean zonal nearequatorial semidiurnal tide; ii) the static calculation of the tide (i.e. using the whole time span as it is usually done) can be misleading, as a number of spurious years are present in some reanalysis; iii) S2 tide variation presents two frequencies at 1 year and 6 months periods; iv) the results from different reanalysis show a great variability and no clear, common pattern in their temporal evolution has been found.