ALBERT

Description / Table of Contents: Zusammenfassung Durch Verwendung einer passend erweiterten Bilanzgleichung für die Elektronendichte-Änderungen während einer Sonnenfinsternis gelinght es erstmalig, die bisher nur theoretisch abgeleiteten Prozesse in derF-Schicht durch die Beobachtungen zu bestätigen und Zahlenmaterial über die Größe der Elektronenproduktionq=q(h), des Wiedervereingungskoeffizienten α=α(h) und die TemperaturT=T(h) zu erhalten. Dieses Zahlenmaterial ist in sich widerspruchsfrei; bemerkenswert ist die Kleinheit von α, wodurch nunmehr auch der nur langsame Abbau der Schicht in der Nacht verständlich wird. Die errechneten Temperaturwerte stimmen gut mit den Ergebnissen von Satellitenmessungen überein.

Description / Table of Contents: Summary Starting-point for our study was the static balance equation where the electron production is equated to the effective recombination. For the latter process we use the generally valid formula $$L = \alpha _0 \cdot p^k \cdot T^n \cdot N^{m + 2} $$ as introduced byBurkard. It was one of our first tasks to find appropriate numerical values for the constantsk, m, n. Thereby the following possibility presented itself: TheN(h) profiles derived from observations are represented in power series, that is in powers of «x», wherex designates the height from the layer peak upwards. Similarly, we can also set up such power series for the scale heightH, the pressurep and the density ρ. A comparison of coefficients thus should enable us to computeH (h) profiles. It turned out, however, in the course of this study that the accuracy of the observational material [e.g. theN (h) profiles at hand] is not sufficient for such a comparison of coefficients, so that we had to look for other ways. We were finally successful in determining from the observational material the numerical values for the hitherto undefined constantsk, m, n. Here two different possibilities result, according as we assume quasi-recombination or quasi-attachment. In many cases, so for instance in the derivation ofH (h) profiles, it did not prove necessary to decide upon one of these two possibilities, so that the computed values are valid for both models. One fact is probably of special importance, namely that the process of electron loss is found as a linear function of the temperature of the neutral gas (or the electron gas). Here further studies will be necessary, in order to interpret this result on the basis of molecular or atomic theory. The model presented in this study is mainly based onN (h) profiles, but agreement is also excellent with observations obtained by the moon-echo method, moreover, with determinations of density derived from satellite orbits. In this connection valuable information is obtained fromH (h) profiles which were computed for many cases and which show the diurnal variation of the scale height. Additional calculations were performed in order to determine the seasonal variation of the scale height at least basically. TheH (h) profiles show that at a height of about 200 km a considerable increase in temperature can be observed in the daytime. There the scale height varies between about 80 km and 170 km (Station Puerto Rico, July). At higher altitudes, however, those variations are considerably smaller, amounting to only about 30 km. In these altitudes we also find gradients of the scale height whose derivation from zero is very slight. Calculation of anN (h) profile obtained by the Scatter-Radar-Method (Bowles) yielded an almost constant scale height from a height of about 340 km upwards to altitudes of 700 km. Seasonal variations, however, proved to be much higher. For the layer maximum under consideration relatively small values for the scale height were found for winter-time and values 1.4 times larger for summer-time. Also the diurnal variation at a height of about 200 km is much less noticeable in the winter-time. The maximum of the scale height changes its height also with the time of the day and the year reaching its maximum at summer noons. Since the present study deals with models only, some of the expressions used for calculation had to suffer a few neglects in order to avoid unnecessary complications. Thus the variation of gravity with height was neglected. Also the diffusion of electrons was not taken into account and present results indicate that those processes of diffusion do not prove as important as is generally assumed. In conclusion we make a few suggestions as to an effective continuation of the investigations reported here.