Аскаплоты советских станций за 1981 год : (оперативно-информационный материал) / Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т. – Апатиты : Кольский филиал АН СССР, 1989.

10 Methods of ascaplotinK. Information about auroras for every station according to /1,2/ is encoded in 5 lines divided by vertical bars. One vertical dividing corresponds to a half-an-hour interval centered at the beginning and middle of each hour (UT). The local geomagnetic midnight is marked by a circle under the ascaplots. Three upper lines show aurora location in the sky. The upper blackened line demonst rates that within a given half-an-hour interval auroras were observed within the scale of zenith angles from 60° to 80° N. The second blackened line corresponds to aurorae in the zenith (from 60° N to 60° S) and the third one marks auroras in the south (from 60° to 80° S). Occurence of auroras in the corresponding part of the sky was marked when an aurora was observed during one minute in a given time interval. Auroral location was defined by its bottom edge. Suppose that the height of the lower edge equals to 100 km then we get that all three angle intervals have approximately sufficient extent along the meridian corresponding to 3 degrees of latitude. Thus, ascaplots give information about spatial distribution of auroras in 9-degree-latitude range within its center in the zenith of the station. It should be taken into account that the sensitivity of all sky cameras is maximum for the zenith and it diminishes when the zenith angle increases. Presence of stars on the films makes it possible to judge °n meteorological conditions in every latitude interval. According to /1,2/ the dot in the middle of the square shows weak cloudiness or cloudiness with rents in the given part of the sky and in the given time-interval. The vertical line denoted complete cloudiness. The tick inside the square of the third line points to bad quality of the ascafilm caused by some technical reasons (inaccurate focusing, poor quality of development etc.). The horizontal line denotes absence of observations. To mark moon lighting which sufficiently reduces the quality of ascafilms we used an additional designa tion, i.e. the horizontal line over the ascaplot. Two bottom lines of squares carry information about auroral activity. Blackening of the very bottom line means that two ball aurora was observed, black ening of other two bottom lines refers to 3 ball auroral activity. It should be noted that the activity in ascaplots does not entirely coincide with brightness of forms. The ball of activity also includes such parameters as the type of the form and its life-time within the given half-an-hour interval. Since the compression of the angle range for the north and south does not permit similar determinations of peculiarities of auroral forms, the auroral activity in ascaplots was estimated only for the zenith region. The series of auroral activity (offered in /7/) characterizing connection between the substorm phase and substorm intensity on one hand, and the type of the form on the other, was taken as a basis. The table for estimating activity is given in Figure 1. Here the balls of activity are marked at the bottom, horizontal lines denote the types of forms (corresponding to the international classification) as well as brightness of forms (W - weak, M - mean, В - bright). Two circles denote duration of observations, the left circle means that the observation period lasted more than that denoted by the right one. The indices by which the balls of activity are calculated are given at the top of the Table. Indices 1-3 correspond to the first ball, whereas indices 4-6 and 7-9 correspond to the second and third ball, respectively. For several forms occuring simultaneously the index is calculated by the most important form plus 1. For example, if during more than