U.A.R - Union des Amateurs Radio

Solar indices:

SSN: 096 – ISN: 063
Area(tot): 978 – New AR today: 0
Solar Flux @2800 MHz: 124 sfu (Penticton)

A lot of water has flowed beneath the bridge from our last bulletin. During the last two months solar activity has been characterized by a tendential growth of the main indices (Sunspot Number, Solar Flux), as we can notice in the plotter below. Since the month of April, the “up and down” curves (caused by the Sun’s rotation and a not-homogeneus dislocation of the sunspots) reached peaks and minimums progressively higher.

Here is the SFI-SSN plot showing indices fluctuation since the beginning of 2012:

Solar disk is today crossed by six different Active Regions, all together decreasing and close to the Western limb of the Star.

However, only one of them, the AR1504, represents 75% of the whole perturbed area. During the past few days it has been also place of the most important flare activity observed on the Sun. Noticeable is the M1.9-class flare occurred three days ago (June 15, 2012).

A double CME, occurred in the past few days on the same Active Region, is reching our Geomagnetic field. They already produced a G1-class storm yesterday as the strong A-index steep rise demostrates.

The following summary table shows more in detail the situation for each AR.

Geomagnetic activity:

A: 39 – K: 3

There are no large coronal holes on the Earthside sun. Geomagnetic field is however enough perturbed due to the double CME occurred around the middle of the month. Expected storms and Auroras at high latitudes.

Here is the K-index variation during the last two days:

Propagation:

If, on one hand, the growth of the main solar indices tend to offer better F2-layer conditions, on the other hand, the strong perturbation affecting our Geomagnetic field nullifies all beneficial effects. This, expecially on the higher bands of HF spectrum. So, MUF will be enough depressed even in the next few days; furthermore, the group of Active Regions now visible will reach the hidden side of the Sun. Therefore general propagation conditions will tend to decrease appreciably, expecially in the Southern Hemisphere areas and on the higher parts of HF. Aurorae, expected in the next few days, will offer good chances at high latitudes.

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73 and good DX

Max Laconca – IK8LOV

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