A model current system associated with multiple auroral arcs

• Main Author: Sesiano, Jean
• Other Authors: Cloutier, Paul A.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 1974
• Subjects: Aurores boréales; Géomagnétisme; Birkeland; Matin; Aurore boréale; aurores boréales; Alaska
• Online Access: https://archive-ouverte.unige.ch/unige:154582

A rocket-borne experiment comprising a vector magnetometer and an array of particle detectors to study the currents and precipitating particles associated with multiple auroral arcs was conducted at Poker Flats, Alaska, on February 2, 1972 at 01:22h local time. The magnetometer measured the magnetic field as the payload passed over the arc system (visual intensity about 20 kR). From the changes in the magnitude and direction of the field, it was possible to build a system of electrojets and Birkeland (field-aligned) currents. Two models were compatible with the data. The first model consisted of four pairs of current sheets, three of them corresponding to visible arcs, aligned in a magnetic east-west direction, of current densities ~30 μA/m² two eastward and one westward electrojet of current magnitude between 1000 and 2000 amperes were also present. They were generally located under the regions of precipitating electrons. The second model is similar to the first one, but two of the current sheets have been replaced by a broader one; it is thus a model consisting of three pairs of current sheets. Unfortunately, no particle data were obtained due to an instrumental failure. Une fusée-sonde, destinée à l'étude des courants et des particules précipitées au voisinage d'une aurore boréale multiple, a été lancée de la base de Poker Flats, en Alaska, le 2 février 1972 a lh22 le matin. La charge utile comprenait un magnétomètre vectoriel et des détecteurs de particules. Le magnétomètre a mesuré les variations du champ magnétique durant le passage de la charge utile au-dessus du système d'arcs, d'une intensité visuelle égale environ a 20 kR. Partant des changements de champ en intensité et direction, il a été possible de construire un modèle comprenant des courants horizontaux (électrojets) et verticaux (parallèles aux lignes de champ), les derniers étant dits "courants de Birkeland". Deux modèles en accord avec les observations sont présentes. Le premier modèle comprend quatres paires de courants de Birkeland ...