Friday, September 30, 2011

Solar & Propagation Sept. 28, 2011

Solar indices:
SSN: 82 – ISN: 70
Area(tot): 1110 – New AR today: 0
Solar Flux @2800 MHz: 139 sfu (Penticton)
Among the five Active Regions on the Sun’s visible hemisphere, the AR1302 is with no dubt the leader. Its surface represents 88% of the whole perturbed area (in the visible hemisphere) and it’s the only AR growing from yesterday: Sunspots +1, Area +30. Also Flare activity, lower enough than in the past few days, is from the big 1302.
Until Region 1301 crosses the West limb, on 03 October, Solar activity is expected to be at high to moderate levels. However, in the next few days a new AR will appear on the southern visible hemisphere and subsequently on both ones.

Geomagnetic activity:
A: 29 – K: (117 nT)
Earth’s magnetic field has been affected by a big storm during the past two days. The following plot shows A-index fluctuations in the last 30 days and the two storms (major & minor) occurred on 26 and 27 Sept. A decrease to quiet levels is expected on 29 – 30 September.

Strong Solar activity isn’t always synonymus of strong propagation. The other side of the coin is constituted, for example, by disturbances on Earth’s magnetic field: this happened in the last two days. Storms switched off high parts of HF, such as 10 and 12m and produced a kind of depression of propagation conditions on the whole spectrum of HF. At the peak of the disturbance, spectacular auroras sighted around North and South Pole. However, in the next few days conditions will increase again in small stages because of the quiet levels of our geomagnetic field.

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