The Sun and Cycle 24 David Treharne, N8HKU Ford Amateur Radio League January 12th, 2012

Why is the sun important Ionization of the upper atmosphere is responsible for reflection of radio waves- allowing for skip propagation around the world. Best distance, the highest frequency that will refract off of the F layer

Ionization is the Key UV radiation Angstroms: F Layer Ionization (best) Soft X-Rays Angstroms: E Layer Ionization Hard X-Rays 1-10 Angstroms: D Layer Ionization, The D layer gets strong during daylight, absorbing lower frequency RF. (No 80m during daylight)

Sunspots are the Key to the F Layer UV Ionization Sunspots emit UV radiation. Sunspots facing the earth activate the F Layer More sunspots= more F ionization It takes several days of sunspots to build up the F Layer, which tends to decrease at night.

Magnetic Explosion on the Sun Each sunspot is actually a pair. A sunspot group is generally 11 spots, due to the calculation method Strong magnetic fields form and explode from the surface UV radiation radiates from around these explosions Sunspots are cooler than the regular surface of the sun, hence they appear darker.

What is causing Sunspots, and How they Appear Magnetic bands appear North and South of the Sun’s equator. These bands generate sunspots. The bands travel toward the equator. The solar cycle is actually 22 years. The bands have a E-W or W-E polarity. During alternate cycles, the bands shift polarity! At the sunspot maximum, the orientation of the sun’s magnetic dipole flips N-S. This is a good way to detect the peak.

How Many Sunspots= Excellent Propogation? Numbers higher than 100= 10 mtrs open a lot. Cycle 23 reached 120 peak Current numbers: Nov: 96.7, Dec: 73 Sunspot Cycle: Ave=11 yrs

Cycle 23 and new Cycle 24 Cycle 23Cycle 24 Smoothed data is actual through Mar, 2011, due to smoothing of 6 months. Rest is estimated through Mar of 2012, then predicted. Monthly data is through Sept, 2011

Solar Flux vs Sunspot Cycles 2800 MHz (10.7 cm) Solar Flux is used as an approximation for the smoothed sunspot number: Smoothed Sunspot number is 6 mo late! The solar flux is daily Solar flux is well below UV wavelength, but it correlates very well.

Sunspots Peak Quickly and Decline Gradually During the Cycle Sunspots start far from the equator, then work their way to the equator. Sunspots are stronger and more numerous at the start of the cycle The beginning of the cycle peaks quicker, then the numbers slowly fall off

Solar Storms The Sun also has storms, which dramatically disrupt communications, and can damage satellites Solar Flares: An eruption that sends RF from VLF to X-Rays into the Earth RF blast causes atmospheric absorption from MHz. Lasts an hour Particles arrive hours later. They interact with the magnetic field, disabling satellites Corona Holes can travel around the sun for months, sending communications down for days

Storm Intensity Measurements K readings are quasi-logrithmic. A ratings are an average of K readings. Kp and Ap are planatary averages. High Ap or Kp are BAD for propagation, as the X rays from the storm ionize the D layer, resulting in radio signal absorption and atmospheric noise.!

January 2012 Spaceweather.com Update January 10, 2012 Sunspots: cm Solar Flux: 129 Planetary K-index Now: Kp= 1 quiet 24-hr max: Kp= 2 quiet

Propogation Lab. Gives Propogaton Skip to 3000km to 4000km. Can use the frequency given in the iso bars in the direction you want to work!

Bibliography ARRL QST Sunspot Cycle.pdf, Sept