GEOPHYSICAL STUDY

Press, Volume CII, Issue 30156, 13 June 1963, Page 10

GEOPHYSICAL STUDY

lonosonde For Raoul Is.

A five-year project to try to correlate meteorological conditions in the ionosphere with the electrical state of the region will be started late this year by the Geophysical Observatory. Department of Scientific and Industrial Research. Christchurch. In its early stages, the project will form part of New Zealand’s contribution to I.Q.S.Y. (the International Year of the Quiet Sun). The observatory already carries out regular ionosonde observations at Christchurch and Campbell Island, but for the purposes of the new survey an extra station will be set up. For the next two years or so, during the sunspot minimum, the additional ionosonde will be in the subtropics at Raoul Island; for the succeeding three years, during the sunspot maximum, it will probably be at Invercargill. The ionosphere contains layers of excited electrons and ionised particles • which reflect and refract radio waves.

At sunspot minimum, the most pronounced impact of meteorology on the electrical conditions is at low latitudes, with practically no effects at all at the latitude of Christchurch or anywhere further south; at sunspot maximum, the greatest effects are at about the latitude of Campbell Island, the purpose of the extra station between there and Christchurch being to study the fine structure of the disturbances. In the Raoul Island observations, which will probably start in September or October, information will be sought on the effect on the ionisation of the F-region (an ionised layer about 150 to 180 miles up) of movements of the atmosphere below about 60 miles. This effect has been observed only in low latitudes, although why it should be restricted to these latitudes is not known. At sunspot maximum, the effect studded will be the way movement of the atmosphere below 60 miles affects the way in which the atmosphere settles into its constituents, and hence the rate of recombination of electrons and ionised atoms—a rate which can be measured at F-region level. This effect has not been observed at low latitudes.