Heliosphere, The Sun and Tilt Angle.

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BY DAVID BIRCH

Hello and welcome to the blog.

For those that have been following my blog you will already know the Heliospheric Current sheets Inclination effects on sunspots and Magnetic field lines associated with the Solar cycle.

For those that do not today we shall go over (basic) understandings of the above,

Firstly the Heliospheric Current sheet is the surface within the Solar system where polarity of the Sun’s Magnetic field changes from North to South. This field extends throughout the Sun’s Equatorial plane in the Heliosphere.

Also known as the Rose Bud or Ballerina Skirt the HCS moves from solar Maximum to solar Minimum, this is called Inclination of the HCS. Inclination moves from 75° to around 7-10° during the course of the Solar cycles, and this is key in looking at progression of any solar cycle vis sunspot activity.

the last 4 solar cycle Tilt angle can be seen in the following graph.

overlaid by myself using original data from the Wilcox solar observatory.

Tilt Angle

The red line above shows the rate of inclination during 4 solar cycles and indeed vary during each cycle. This was put together back in 2017 with my pointer to 2019, you will notice at this time my projection was for cycle 24 to go past the year 2019 into 2020/21.

This was purely set from looking at the Tilt angle of the previous 3 cycles and a 10° flat inclination which denotes solar cycle minimums of cycle 21/22/23.

we can now look at the most current data and Tilt angle of the HCS.

 

Tilt angle Feb 2019

 

Here we can see that indeed the Tilt angle of the HCS is currently at 27° after a shift in the Inclination from 18-27° suggesting that cycle 24 is not yet ready to go into solar minimum in line with previous cycles.

we do however observe a “sudden drop” of the HCS when nearing solar minimum so we have 2 scenarios here.

1…previous cycles suggest a shift “positive” prior to a steep drop in the tilt angle.

2…The increase in Tilt angle may continue for the remainder of 2019 prior to a sudden drop to minima around 2020/2021.

My guess (and that is all it can be) based on previous progression is that the remainder of 2019 will not see the sudden drop, and we will see the inclination fall during 2020 with minima late 2020 early 2021, however the powers that be may not “officially” call solar minima at this point.

we can now look at the HCS/Sunspot progression.

A peak in the sunspot count is referred to as a time of “solar maximum” (or “solar max”), whereas a period when few sunspots appear is called a “solar minimum” (or “solar min”). An example of a sunspot cycle spans the years from the solar min in 1986, when 13 sunspots were seen, through the solar max in 1989 when more than 157 sunspots appeared, on to the next solar min in 1996 (ten years after the 1986 solar min) when the sunspot count had fallen back down to fewer than 9.

Along with the number of sunspots, the location of sunspots varies throughout the sunspot cycle. At solar min, sunspots tend to form around latitudes of 30° to 45° North and South of the Sun’s equator. As the solar cycle progresses through solar max, sunspots tend to appear closer to the equator, around a latitude of 15°. Towards the end of a cycle, with solar min once again approaching, sunspots form quite close to the solar equator, around 7°-10° North and South latitude. Starting to see the picture yet?

OVERLAP

Many people have asked me what the Overlap is so let us look at this now.

There is often an overlap in this latitudinal migration trend around solar min, when sunspots of the outgoing cycle are forming at low latitudes and sunspots of the upcoming cycle begin to form at high latitudes once again. This gradual equatorward drift of sunspots throughout the sunspot cycle, which was first noticed in the early 1860’s by the German astronomer Gustav Spörer and the Englishman Richard Christopher Carrington, is often called Spörer’s Law. In 1904 another English astronomer, Edward Walter Maunder, constructed the first “butterfly diagram”, a graphical plot of this sunspot migration trend.

here we can see a visual of “old and new” sunspots using their Theory.

We can see from the above the strongest cycle in the diagram was during 1960 cycle 19 and sunspot progression drifting SE to the equator which indicates solar minimum. we can also see from the side graph incoming and outgoing sunspot relation.

a great example of located sunspots is shown in the graph below.

Sunspot location 2001-2005

2005 at this point had zero sunspots Earth facing however notice the location at solar max a mixture of outgoing cycle spots (Equator) incoming 30-40°N.

The 11-year sunspot cycle is actually half of a longer, 22-year cycle of solar activity. Each time the sunspot count rises and falls, the magnetic field of the Sun associated with sunspots reverses polarity; the orientation of magnetic fields in the Sun’s northern and southern hemispheres switch. Thus, in terms of magnetic fields, the solar cycle is only complete (with the fields back the way they were at the start of the cycle) after two 11-year sunspot cycles. This solar cycle is, on average, about 22 years long – twice the duration of the sunspot cycle.

Summing up the importance of the location of Sunspots and the Inclination Tilt angle of the HCS is very important in estimating the period at which we will see solar Max/Min IS OBVIOUS HOWEVER not necessarily a foregone conclusion as we have seen the tilt angle can and will change during the “drop” to solar minimum.

Also keep our eyes open for regular incoming sunspots at higher latitudes not simple sporadic “rogue” sunspot activity.

Thanks for viewing

David.

 

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