The difference in variation characteristics of the F2-peak height hmF2 at the low and middle latitudes

There is a continuing requirement for simple, but representative methods for determining the height of maximum electron concentration of the F2-layer (symbol hmF2), both for communication and navigation. The techniques for estimating the F2-peak height hmF2 from M(3000)F2 are reviewed with particular stress put upon those in which the effects of underlying ionization are accounted for by a correction to M(3000)F2, formulated in terms of the ratio f0F2 and f0E. Changes in the neutral atmosphere and in the hmF2 model have minor effects at low latitudes, where the fluxes are larger, but can appreciably alter the results at middle latitudes. At 21° latitude, neutral winds have a major effect on the distribution of ionization from the equatorial fountain. Thus, at the solstices the day-time flow is about 4 times larger in winter than summer. This paper reports on a comparison of the difference in variation characteristics of the observed monthly mean ionospheric F2-peak height hmF2 at Lanzhou (36.06°N latitude) and Haikou (20°N latitude) for both solar minimum (2005-2007) and solar maximum (2010-2011). The diurnal, seasonal, and solar variation of the hmF2 at the two sites compared with results of detailed calculations. Also, the contemporary practical implementations will be compared and contrasted in the light of this investigation and the scope for further refinements will be discussed.