Winter-time dependence of the global TEC on the stratospheric temperature and solar radiation

This paper presents a simple linear regression model that enables to quantify the contribution of high-latitude stratospheric temperature and solar radiation (describes by its proxy F10.7) to the variability of the low-latitude TEC during winter. The model is based on cross-correlation analysis performed on the Aura MLS temperature measurements and the global CODE TEC data for the period of time 2005-2010, i.e. at low to moderate solar activity (F10.7 changes between ~65 and ~140 solar flux units). It revealed that the temperature at altitude of ~40 km and latitude of ~60°N describes the most typical winter conditions and shows the largest negative correlation with the low-latitude TEC. This temperature namely is included in the regression model. The model results have been compared with the TEC data by calculating the standard deviation (STD). The comparison indicated that the regression model describes almost half of the real variability of the global TEC and that the contribution of the temperature (that is only a part of forcing from below) is almost half of the solar variability (i.e. external forcing related to the photo-ionization). A possible mechanism for explaining the relationship between the high-latitude stratospheric increase of the temperature and low-latitude decrease of the TEC is suggested.