Association between ionospheric maximum electron density and lower stratospheric temperature

A correlation has been found between the peak electron density of the ionospheric F2 layer, Nmax, and the temperature of the lower stratosphere. The electron density anomaly, NmaxA, and the 12-month running mean of the lower stratospheric temperature anomaly (LSTA) are correlated. NmaxA is the residual of the linear regression of Nmax on the sunspot number, Rz; and LSTA is the difference between the lower stratospheric temperature and its mean value. Monthly median values at 1200 LT of Nmax measured at Yamagawa, Kodaikanal, Okinawa, and Manila ionospheric stations are considered, covering the period 1979–1994. The lower stratospheric temperature corresponds to monthly mean values of the period January 1979 to December 1993. Since solar EUV and UV radiation affect the F2 layer ionization and the stratospheric heating respectively, the part of the EUV and UV flux time variation that is not dependent on Rz has also been analyzed. This has been done using the photoelectron current (Ipe) measured with a Langmuir Probe on the Pioneer Venus Orbiter as indicator of the EUV flux, and the Mg II core-to-wing ratio as indicator of the UV flux. The temporal variations of Nmax independent of Rz are found to be similar to LSTA variations. The temporal variations, not dependent on Rz, of the solar EUV and UV energy output, are also similar.