Cosmic noise absorption pulsations ...

• Main Author: Reid, JS
• Format: Thesis
• Language: unknown
• Published: University Of Tasmania 2023
• Subjects: Macquarie Island
• Online Access: https://dx.doi.org/10.25959/23244947.v1; https://figshare.utas.edu.au/articles/thesis/Cosmic_noise_absorption_pulsations/23244947/1

The fast cosmic noise absorption (c.n.a.) pulsations observed with fast response riometers at Macquarie Island in the southern auroral zone are discussed in relation to the parameters of the lower ionosphere. The pulsations which are similar to and associated. with pulsations in aurora luminosity (at ˜í¬™ 4278‚àövñ), Pi2 micropulsations and fast bremmstrahlung X-ray pulsations are unique in that they exhibit a time asymmetry or relaxation time which is believed to be a consequence of the relatively slow rate of removal of secondary electrons in the ionosphere. The relaxation time, T is defined as ˜ìvë = - A/ (¬ªvü) max where A is the amplitude of the pulse,above background and (¬ªvü)max is the Maximum (negative) slope of the relaxation part of the pulse. Measured values of ˜ìvë varied between 1 and 30 seconds and scatter diagrams of ˜ìvë versus A indicate a strong tendency for ˜ìvë to increase with increasing pulse amplitude. The properties and anomalies of the D-region of the ionosphere are discussed, as is ...