Regular reports of my grabber activity and that of others, plus information on QRSS software, hardware and technique that comes my way

Sunday, July 15, 2012

CME Effect on 40m QRSS Signal

This post is to document the effect of a Coronal Mass Ejection (CME) on a QRSS signal propagating between New Mexico (WA5DJJ) and Florida (W4HBK).  The CME occurred on July 12 and was described in my last post.

Figure 1 shows the observed effect.  DJJ transmits a fsk cw signal referenced to a Rubidium frequency standard which at this time scale produces two parallel lines corresponding to the fsk mark and space.  The Master Oscillator of my TS-440 is temperature controlled, thus the observed frequency changes are due to Doppler shifts caused by motion of the ionosphere.   As luck would have it, Dave's signal came on just before the start of the disturbance while the QRM ceased at the same time.

Figure 1.  Frequency shift of WA5DJJ signal during geomagnetic disturbance

Note these features:

1.  Start time is about 0345z
2.  As the event progressed four separate layers developed as the frequency shifted downward followed by a reversal with a decaying sine wave pattern.
3.  The apparent speed of the wave was very slow with a period or 1 to 2 hours.

Figure 2 is a corresponding magnetometer recording from Anchorage, AK which indicates time history of the geomagnetic disturbance.

Figure 2.  Geomagnetic disturbance recorded at Reeve Engineering Labs in Anchorage, AK

This leaves little doubt that the observed effect on the QRSS signal was caused by the disturbance.  However, this was not the initial arrival of the CME.  As shown in Figure 3 that actually occurred the day before at 1700z.

Figure 3.  CME history recorded by ACE spacecraft (~ 1 hr before before seen at Earth)

Our observation was related to the minor hump occurring at about 0300z.  I had made an effort to be watching for the arrival as predicted at but, again as luck would have it, the presence of lightning forced me to secure my station at that time.

Here's how I visualize the storm as depicted in Figure 1.  After the particles slammed into Earth around the Auroral Zone an ionospheric wave spread out at a surprisingly slow speed.  This wave is indicated by the exponentially decaying sine nature of the frequency variations.  The splitting of the frequency into 4 components is also surprising and could imply either a stacked vertical layering or possibly skip points spread out horizontally...but why 4?  In conclusion, I find both the layering and the slow speed with which the disturbance spread to be remarkable.

de w4hbk

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