The Solar X-Ray flux arises from two factors. Firstly, there
is flux coming from sunspot regions and other
features - the background flux - and this varies slowly
from day-to-day. Secondly, solar flares produce
large amounts of X-ray flux, but this is concentrated to the
duration of the flare which is usually from
minutes to several hours.
Solar X-Ray Flux is described as follows:
Level Flux (watts/sq meter) Description
A less than 10-8 Very Low Background
A between 10-8 and 10-7 Low Background
B between 10-7 and 10-6 Moderate Background
C between 10-6 and 10-5 High Background/Low Flare
M between 10-5 and 10-4 Moderate Flare
X between 10-4 and 10-3 High Flare
Y greater than 10-3 Extreme Flare
where ** indicates a power [e.g. 10-2 equals 0.01]. Within
these levels, a number is used
to specify the flux. Hence a value M3.2 indicates that the
flux is 3.2 x 10-5 watts/sq meter.
The Y classification of flares is new; and these extremely large flares are
often still classed as X flares with a qualifying number greater than 10.
Hence a Y1.6 flare is exactly the same as an X16 one.
Material Prepared by Richard Thompson. © Copyright IPS - Radio and Space Services.
Educational