Edward V. Appleton

Bio: Edward V. Appleton is an academic researcher from University of Edinburgh. The author has contributed to research in topics: Ionosphere & Ionospheric heater. The author has an hindex of 9, co-authored 17 publications receiving 994 citations.

Two Anomalies in the Ionosphere

Abstract: DURING the War, many new ionospheric stations were instituted in different parts of the world to serve the operational requirements of the Allied Forces. As a result, there have become available, for the first time, sufficient data to provide a rough general morphological picture of the F2 layer of the ionosphere. A study of these data has disclosed the remarkable result that, although ionospheric events in the E and F1 layers are similarly reproduced at the same local time on the same day at all locations on a line of constant geographic latitude, the same is by no means the case for the F2 layer. It has also been confirmed, as was suspected earlier, that under conditions of symmetrical solar illumination, an asymmetry of ionization exists for certain station on the same longitude and situated at equal latitudes north and south of the equator.

Local Reflection of Wireless Waves from the Upper Atmosphere

Abstract: IN some recent experiments carried out for the Radio Research Board of the Department of Scientific and Industrial Research, measurements have been made of the diurnal variation of the signals received at Cambridge from the stations of the British Broadcasting Company. During the day-time these signals have been found to be fairly constant, but night-time variations of intensity have been measured at distances from the transmitter so short as 50 miles. For example, the signals from London at Cambridge are found to be constant during the day; but, at about sunset, variations, which are often of a periodic character, begin, and continue through the dark hours. In this case the mean night value is very little different from the day value. For more distant stations (for example, Bournemouth) the phenomena are different. During the day the signal is weak and constant; but after sunset the intensity increases and, though variable, the signal maxima may be several times the day value. In this case the variations in signal intensity are larger, less rapid, and less markedly periodic than in the case of the London signals.

Control of equatorial ionospheric morphology by atmospheric tides

Abstract: [1] A newly discovered 1000-km scale longitudinal variation in ionospheric densities is an unexpected and heretofore unexplained phenomenon. Here we show that ionospheric densities vary with the strength of nonmigrating, diurnal atmospheric tides that are, in turn, driven mainly by weather in the tropics. A strong connection between tropospheric and ionospheric conditions is unexpected, as these upward propagating tides are damped far below the peak in ionospheric density. The observations can be explained by consideration of the dynamo interaction of the tides with the lower ionosphere (E-layer) in daytime. The influence of persistent tropical rainstorms is therefore an important new consideration for space weather. Citation: Immel, T. J., E. Sagawa, S. L. England, S. B. Henderson, M. E. Hagan, S. B. Mende, H. U. Frey, C. M. Swenson, and L. J. Paxton (2006), Control of equatorial ionospheric morphology by atmospheric tides, Geophys. Res. Lett., 33, L15108, doi:10.1029/2006GL026161. [2] The ionosphere is the region of highest plasma density in Earth’s space environment. It is a dynamic environment supporting a host of plasma instability processes, with important implications for global communications and geo-location applications. Produced by the ionization of the neutral atmosphere by solar x-ray and UV radiation, the uppermost ionospheric layer has the highest plasma density with a peak around 350–400 km altitude and primarily consists of O + ions. This is called the F-layer and it is considered to be a collisionless environment such that the charged particles interact only weakly with the neutral atmosphere, lingering long after sunset. The E-layer is composed of molecular ions and is located between 100–150 km where collisions between ions and neutrals are much more frequent, with the result that the layer recombines and is reduced in density a hundredfold soon after sunset [Rees ,1 989;Heelis, 2004]. The respective altitude regimes of these two layers are commonly called the E- and F-regions. [3] The ionosphere glows as O + ions recombine to an excited state of atomic oxygen (O I) at a rate proportional to

lonization transport effects in the equatorial F region

Abstract: Continuity equation for electrons in F-2 layer obtained for region near geomagnetic equator at noon including photoionization, recombination, drift, etc

The equatorial electrojet

Abstract: An integrated treatment of observations and models of the undisturbed equatorial electrojet is presented. Previous reviews have concentrated on particular aspects of the electrojet phenomenon, such as ground magnetic variations, the counterelectrojet, or E region electron density irregularities and associated plasma instabilities. Here accomplishments during the past 15 years involving all aspects of the phenomenon are covered and, where possible, interrelated. Observational and theoretical studies during recent years have emphasized the local time, longitude, vertical, and latitudinal structure of electric fields and currents in the electrojet; this review similarly places its emphasis along these lines and by necessity involves a detailed examination of electrodynamic coupling with the neutral atmosphere tidal oscillations in temperature, composition, and winds. The review concludes with an assessment of current knowledge concerning the equatorial electrojet and suggestions for the future direction of observational and theoretical research on electrodynamical processes in the equatorial ionosphere.