The Aurora Code
Aurora Codes. Are a set of abbreviations used to record and report auroral activity. Aurora code offers a quick and convenient means of recording the condition, qualifying symbol, structure, form, brightness and colour of a display:
Auroral activity observed should be recorded using the code below on a report sheet drawn up in accordance with the sample provided below. The observer should enter a new line of data whenever the aurora is seen to change in form or activity. It may be necessary to fill in more than one line if more than one form is active at the same time. If in doubt, draw a sketch on which is written the necessary
Condition Qualifying Symbol
Code Definition Code Definition
q | Quiet. No Movement | m | Multiple. Several groups of forms | |
a | Active | f | Fragmentary. A part only of an auroral form | |
a1 | Folding of Bands | c | Coronal. Rays converging | |
a2 | Rapid Change of Shape of Lower Form | Structure | ||
a3 | Rapid Horizontal Movement of Rays | Code | Definition | |
a4 | Forms fade quickly to be replaced by others | H | Homogeneous. Uniform in shape and intensity | |
p1 | Pulsing. Rythmic change of form as a whole | S | Striated. Lines of brighter and darker light | |
p2 | Flaming. Variations moving upwards | R1 | Rayed. Short Rays | |
p3 | Flickering. Rapid irregular variations | R2 | Rayed. Medium Length Rays | |
p4 | Streaming. Irregular horizontal variations in homogenious forms. | R3 | Rayed. Long Rays | |
Form | Brightness | |||
Code | Definition | Code | Definition | |
G | Glow. Brightness from horizon upwards. | 1 | Weak. Barely visible | |
A | ARC. Uniformly curved arch of light. | 2 | Bright as moonlit cirrus cloud | |
RA | Rayed ARC from which rays appear. | 3 | Bright as moonlit cumulus cloud | |
R | Ray. A vertical shaf | 4 | Strong. Bright enough to cast shadow | |
B | Band. Twisted ARC | |||
V | Veil. Indefinite | |||
P | Patch. Isolated “cloud ” of aurora. | |||
N | Undefined. Does not identify with other forms. | |||
Colour | ||||
Code | Definition | |||
a | Red Only in upper portion of form | |||
b | Red Lower Border only | |||
c | White Green or Yellow | |||
d | Red | |||
e | Red and Green | |||
f | Blue or Purple |
Aurora code is used in the following format: condition|qualifying|structure|form|brightness|colour
Example: a3|cf|R|B|2|c
Is a fragment of white, green or yellow rayed band as bright as moonlit cirrus cloud, forming a
corona in the magnetic zenith. Confusion between corona (c) and colour class (c) is defined by
the columns in which the codeletters are ntered in the report forms
Auroral activity observed, should be recorded using the report sheet, and drawn up in accordance with the sample provided above. The observer should enter a new line of data whenever the aurora is seen to change in form or activity. It may be necessary to fill in more than one line if more than one form is active at the same time. If in doubt, draw a sketch on which is written the necessary data:
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