[OKDXA] New Solar Cycle

[Kim Elmore]

Having read in replies here that there is a fair 
bit of confusion about what this says, along with 
some derision about why it's written the way it is, I looked it all up.

Concerning the terms used (nomenclature), 
remember that discussions like this are usually 
intended for an audience that's pretty familiar 
with some of the details of the subject matter, 
much like a meteorological discussion like might be found here

http://www.crh.noaa.gov/product.php?site=NWS&issuedby=OUN&product=AFD&format=CI&version=1&glossary=1

The discussion above is intended for other 
meteorologists, but is also made available to the 
general public as a matter of course. What you 
see reported by Dave (which came from 
spaceweather.com, but was created in Boulder at a 
solar forecast lab there. It is a discussion 
intended primarily for geophysicists and other 
solar physicists, so it uses the terms of their discipline.

As for the terms used, here goes:

At 09:25 AM 1/5/2008, you wrote:
>Here's more info:
>
>Joint USAF/NOAA Report of Solar and Geophysical Activity
>SDF Number 004 Issued at 2200Z on 04 Jan 2008
>
>IA.  Analysis of Solar Active Regions and Activity from  03/2100Z
>to 04/2100Z:  Solar activity was very low.  Region 980 (S06E29)

These numbers identify the active region (active 
regions include sunspots among other solar 
phenomenon) with respect to an arbitrary 
numbering system started 5 January 1972. Active 
region 10000 was recorded on 14 June 2002. 
Because of the formatting conventions of this 
numbering system, they can receive only four 
numbers. Hence, region 10000 was referred to as 
region 0000. Sometimes, the preceding zero in 
understood, so in the case above, what we really have is region 10980.

However, we see only the regions on the side of 
the sun that faces us, and the sun rotates about 
once every 27 days (the equator rotates faster 
than the polar regions). Each region receives a 
number as it appears on the limb of the visible 
disc, so its possible that the same region may 
survive an entire rotation. However, because we 
cannot follow it all the way around, and because 
these things change fairly rapidly, there's no 
way of knowing that it's the same region. Hence 
it receives a new number. Very long-lived regions 
can receive several different numbers.

The location given for the region (S06E29) gives 
its location on the visible disc using 
heliographic latitude and longitude. This is a 
coordinate system that applies only to the 
visible disc, not the entire sun, unlike terrestrial longitude and latitude.

How heliocentric longitude and latitude are 
determined (it's not trivial) is explained here 
http://www.petermeadows.com/html/location.html.

>produced one low level B-class flare during the past 24 hours.

Solar flares are classified as A, B, C, M or X 
according to the peak flux (in watts per square 
meter, W/sq meter) of 100 to 800 picometer X-rays 
near Earth, as measured on the GOES spacecraft. 
Each class has a peak flux ten times greater than 
the preceding one, with X class flares having a 
peak flux of order 10-4 W/sq meter. Within a 
class there is a linear scale from 1 to 9, so an 
X2 flare is twice as powerful as an X1 flare, and 
is four times more powerful than an M5 flare. 
Hence, a B-class flare has a peak X-ray flux of about 10-7 W/sq meter.

>   The
>region continued to decay and is now classified as a simple Axx
>sunspot group.

This classification method (the McIntosh Sunspot 
Group Classification) uses one capital letter and 
two lower case letters. A means that it is a 
unipolar sunspot group (only one magnetic 
polarity), the first x means that the spot has no 
penumbra (a lighter region surrounding the 
darkest area, called the umbra), and the second x 
is simply a place filler. This is the simplest kind of sunspot.

>New Region 981 (N30E22) is classified as a Cso beta
>sunspot group.

This group (full number is 10981) appears 30 deg 
North of the equator (N30E22) and 22 deg East of 
the central meridian. New sunspot groups usually appear at mid-latitudes.

C - Bipolar group with penumbra on one end of 
group, usually surrounding largest of leading umbra
s - Small, symmetric penumbra, elliptical or 
circular and N-S size smaller than 2.5°.
o - open - few, if any, spots between leader and follower spots.

Beta comes form the Mount Wilson observatory 
magnetic classification system and may be 
somewhat redundant here. Beta means a sunspot 
group having both positive and negative magnetic 
polarities, with a simple and distinct division between the polarities.

>This region is likely a new solar cycle sunspot
>group.  A very faint backsided CME

CME refers to a coronal mass ejection. A CME is 
an ejection of material from the solar corona, 
usually observed with a white-light images of the 
solar coronal, called a coronagraph. "Backside" 
refers to the trailing region of the sunspot group

>  was observed on LASCO C2 imagery
>at 4/1454Z.

LACO refers to the Large Angle and Spectrometric 
Coronagraph Experiment. The C2 refers to the C2 
coronagraph, which images the corona from about 1.5 to 6 solar radii.

There!  Now you know something about how to interpret these discussions.

73,

Kim Elmore (N5OP)