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Sunday, May 19, 2013

Solar Flare Propels Coronal Mass Ejection Towards Earth and Likely Will Cause Geomagnetic Storms Starting Today, May 19, 2013

CME IMPACT: A CME hit Earth's magnetic field on May 19th at 2250 UT (3:50 PM PDT). Polar geomagnetic storms and high-latitude auroras are possible in the hours ahead. Stay tuned for updates. 

The CME was propelled toward Earth on May 17th by an M3-class solar flare in the magnetic canopy of sunspot AR1748. SOHO took this picture of the CME racing away from the sun at 1500 km/s (3.4 million mph):


It was hurled into space by an M3-class solar flare in the magnetic canopy of sunspot AR1748. In the video, the CME appears to hit Mercury, but it does not. It is merely passing in front of the innermost planet. The planet in the line of fire is Earth.

AURORAS INVADE THE USA: A CME hit Earth's magnetic field on May 18th at around 0100 UT. Although it was just a glancing blow, the impact was enough to spark a G1-class geomagnetic storm. In the United States, Northern Lights descended as far south as Pawnee Buttes, Colorado:


"The aurora was not visible to the naked eye," says photographer Robert Arn. "Only with a 30 second exposure did I know it was there. As I started to collect data, I noticed an electrical storm in the distance. The juxtaposition of the electrical storm and aurora made for a spectacular image. (The moon near the horizon illuminated the landscape.)"

Elsewhere in the United States, faint auroras were photographed in Michigan, Massachusetts, Washington, Vermont, and Iowa. Browse the aurora gallery for more sightings.


Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 4 
unsettled
explanation | more data
Interplanetary Mag. Field
Btotal13.8 nT
Bz3.3 nT south 
explanation | more data
Updated: Today at 2357 UT

SWPC ACE RTSW MAG 24-hour Updating Plot

3-day Estimated Planetary K-index graph


The K-index

The K-index is a code that is related to the maximum fluctuations of horizontal components observed on a magnetometer relative to a quiet day, during a three-hour interval. The conversion table from maximum fluctuation (nT) to K-index, varies from observatory to observatory in such a way that the historical rate of occurrence of certain levels of K are about the same at all observatories. In practice this means that observatories at higher geomagnetic latitude require higher levels of fluctuation for a given K-index. The conversion table for the Boulder magnetometer is shown below:
K
nT
0
0-5
1
5-10
2
10-20
3
20-40
4
40-70
5
70-120
6
120-200
7
200-330
8
330-500
9
>500
At SWPC, we monitor the preliminary values of the K-index, minute by minute, from a network of observatories that relay data in near-real time. The final K-indices are determined after the end of prescribed three hourly intervals (0000-0300, 0300-0600, ..., 2100-2400). The maximum positive and negative deviations during the 3-hour period are added together to determine the total maximum fluctuation. These maximum deviations may occur anytime during the 3-hour period.


Relationship between Kp and the Aurora [ref]
Right: From thousands of observations, Cornell University scientists have determined geographic subpoints for the southern edges of auroral displays. The curves represent four values of the planetary index (Kp). As this index increases, the aurora's southern edge moves southward

In this article we briefly explain some of the ideas behind the association of the aurora with geomagnetic activity and a bit about how the ‘K-index’ or ‘K-factor’ works. The aurora is understood to be caused by the interaction of high energy particles (usually electrons) with neutral atoms in the earth's upper atmosphere. These high energy particles can ‘excite’ (by collisions) valence electrons that are bound to the neutral atom. The ‘excited’ electron can then ‘de-excite’ and return back to its initial, lower energy state, but in the process it releases a photon (a light particle). The combined effect of many photons being released from many atoms results in the aurora display that you see.

The details of how high energy particles are generated during geomagnetic storms constitute an entire discipline of space science in its own right. The basic idea, however, is that the Earth’s magnetic field (let us say the ‘geomagnetic field’) is responding to a outwardly propagating disturbance from the Sun. As the geomagnetic field adjusts to this disturbance, various components of the Earth’s field change form, releasing magnetic energy and thereby accelerating charged particles to high energies. These particles, being charged, are forced to stream along the geomagnetic field lines. Some end up in the upper part of the earth’s neutral atmosphere and the auroral mechanism begins.

The disturbance of the geomagnetic field may also be measured by an instrument called a magnetometer. At our operations center we receive magnetometer data from dozens of observatories in one minute intervals. The data is received at or near to ‘real-time’ and allows us to keep track of the current state of the geomagnetic conditions. In order to reduce the amount of data that our customers have to deal with we convert the magnetometer data into three-hourly indices which give a quantitative, but less detailed measure of the level of geomagnetic activity. The K-index scale has a range from 0 to 9 and is directly related to the maximum amount of fluctuation (relative to a quiet day) in the geomagnetic field over a three-hour interval.

The K-index is therefore updated every three hours and the information is made available to our customers as soon as possible. The K-index is also necessarily tied to a specific geomagnetic observatory. For locations where there are no observatories, one can only estimate what the local K-index would be by looking at data from the nearest observatory, but this would be subject to some errors from time to time because geomagnetic activity is not always spatially homogenous. Another item of interest is that the location of the aurora usually changes geomagnetic latitude as the intensity of the geomagnetic storm changes. The location of the aurora often takes on an ‘oval-like’ shape and is appropriately called the auroral oval. A useful map of the approximate location of the auroral oval as a function of the Kp-index was published in the June 1968 copy Sky & Telescope (see page 348). The Kp index is derived through by an algorithm that essentially averages the K-indices from several stations. Note that as a storm becomes more intense, the edge of the auroral boundary typically moves to lower latitudes.

For further reading we can recommend a couple of books for you. An old, but classic text is The Polar Aurora, Oxford University Press, 1955, by Störmer. A more modern text is The Physics of Space Plasmas, 1991, by George Parks. If you are interested in real-time reporting of geomagnetic activity please make use of our 24-hour/day, 7 day/week services. We have an internet home page address (/), and a recorded message which is updated every three hours or as major activity occurs (303-497-3235). You can also reach us at 303-497-3204. We hope that you find this information helpful. If you have some further questions please don’t hesitate to let us know. Best wishes ! Chris Balch (cbalch@sec.noaa.gov)


SPACE WEATHER
NOAA Forecasts
Updated at: 2013 May 19 2200 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
65 %
65 %
CLASS X
25 %
25 %
source: source: http://spaceweather.com/


3-day GOES X-ray Plot
The GOES X-ray Flux plot contains 5 minute averages of solar X-ray output in the 1-8 Angstrom (0.1-0.8 nm) and 0.5-4.0 Angstrom (0.05-0.4 nm) passbands. Data from the SWPC Primary and Secondary GOES X-ray satellites are shown. Some data dropouts from the Primary satellite will occur during satellite eclipses.
source: http://www.swpc.noaa.gov/rt_plots/xray_5m.html

SWPC ACE RTSW MAG & SWEPAM 24-hour Updating Plot

source: http://www.swpc.noaa.gov/ace/MAG_SWEPAM_24h.html


Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels:activeminor stormsevere storm

Updated at: 2013 May 19 2200 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
35 %
15 %
MINOR
30 %
05 %
SEVERE
20 %
01 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
05 %
15 %
MINOR
20 %
25 %
SEVERE
75 %
25 %


ACTIVE:

Geomagnetic Storm Forecasts
The geomagnetic storm probabilities are the estimated chances of at least one 3-hour K index, at the indicated level, for each of the next 3 days.

Active: K = 4.
Minor storm: K = 5.
Major or Severe storm: K > 6.

The "K index" is a 3-hourly quasi-logarithmic local index of geomagnetic activity relative to an assumed quiet-day curve for the recording site. Range is from 0 to 9. The K index measures the deviation of the most disturbed horizontal component of the magnetic field.
http://spaceweather.com/glossary/geostorm.html

MINOR:

Geomagnetic Storm Forecasts
The geomagnetic storm probabilities are the estimated chances of at least one 3-hour K index, at the indicated level, for each of the next 3 days.

Active: K = 4.
Minor storm: K = 5.
Major or Severe storm: K > 6.

The "K index" is a 3-hourly quasi-logarithmic local index of geomagnetic activity relative to an assumed quiet-day curve for the recording site. Range is from 0 to 9. The K index measures the deviation of the most disturbed horizontal component of the magnetic field.


http://spaceweather.com/glossary/geostorm.html

SEVERE:
Geomagnetic Storm Forecasts
The geomagnetic storm probabilities are the estimated chances of at least one 3-hour K index, at the indicated level, for each of the next 3 days.

Active: K = 4.
Minor storm: K = 5.
Major or Severe storm: K > 6.

The "K index" is a 3-hourly quasi-logarithmic local index of geomagnetic activity relative to an assumed quiet-day curve for the recording site. Range is from 0 to 9. The K index measures the deviation of the most disturbed horizontal component of the magnetic field.

http://spaceweather.com/glossary/geostorm.html





2 comments:

dan said...

Anything to do with the twisters raging through USA today?

Natasha Call said...

That will be coming up soon!