[NZ4O Spaceweather] Upward Trend Of Indices Slows

[Thomas F. Giella NZ4O]

As of this morning UTC the solar flux reached 113.2 and the sunspot number 
105, as the upward trend continues but at a slower rate.

The indices are high enough once again for east-west radiowave propagation 
on 10 meters. Radiowave propagation conditions continue to improve as the 
two plus day geomagnetic storm ended yesterday. However 160 and 80 meter 
band conditions will take longer to improve across lower latitudes due to a 
stoked up (ERC)equatorial ring current.

>From http://www.wcflunatall.com/nz4o5.htm the ERC is a phenomenon that acts 
as a repository for precipitated electrons in the vicinity of the magnetic 
equator. The electrons travel by spiraling around north south magnetic field 
lines at a frequency called the gyro frequency. The end result is lower 
latitude propagation path medium and lower HF frequency transmitted RF 
signal blockage and absorption via the D layer. Absorption is similar to 
higher latitude Aurora Oval absorption and is inter-related with same.

A reliable gauge for measuring the up to three day lingering post 
geomagnetic storming medium frequency transmitted RF absorption is the Dst 
index, measured in nT's. It is an estimated value from Kyoto Japan and is 
based on a formula. Large negative values after a major geomagnetic storm 
indicates a high Equatorial Ring Current level. (See definition #2. Aurora 
Oval Blockage, Absorption And Refraction). Here is a website link to the 
Kyoto, Japan Dst Index 
http://swdcwww.kugi.kyoto-u.ac.jp/dst_realtime/presentmonth/index.html and 
the U.C. Berkeley website link http://sprg.ssl.berkeley.edu/dst_index and a 
NASA GSFC website link http://sprg.ssl.berkeley.edu/dst_index . (See 
definition #2. Aurora Oval Blockage, Absorption And Refraction). Another 
excellent source of a daily Dst figure is at 
http://www.alan.melia.btinternet.co.uk/latest.htm .

The geomagnetic storm pretty much wrecked radiowave propagation conditions 
last weekend, thanks to a geoeffective (earth facing) coronal hole in unison 
with a coronal mass ejection (CME), which was hurled at earth by a 
collapsing magnetic filament. We saw 12 hours of moderate geomagnetic (Kp-6) 
storming, 2 hours with minor (Kp-5) geomagnetic storming and 15 hours of 
active (Kp-4) geomagnetic conditions.

73 & GUD DX,
Thomas F. Giella, NZ4O
Lakeland, FL, USA
nz4o at arrl.net

eMail Reflector Moderator & Owner

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