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

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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