The K7RA Solar Update


The activity we could see recently on our Sun’s far side -- thanks to the STEREO mission -- has been rotating into view, producing some nice sunspot activity and the resulting improved upper-HF propagation. Compared to the previous week (March 17-23), the past week (March 24-30) showed average daily sunspot numbers up more than 61 points to 102.1, while the average daily solar flux up nearly 20 points to 114.7. Geomagnetic conditions were quieter as well, and reports from readers show greatly improved propagation on 20, 15 and10 meters.

Sunspot numbers for March 24-30 were 73, 104, 104, 132, 103, 108 and 91, with a mean of 102.1. The 10.7 cm flux was 107.6, 112.6, 114.5, 115.6, 118.5, 116.2 and 117.6, with a mean of 114.7. The estimated planetary A indices were 4, 3, 1, 2, 3, 4 and 5, with a mean of 3.1. The estimated mid-latitude A indices were 3, 2, 1, 2, 2, 2 and 4, with a mean of 2.3. This table shows a new sunspot group on March 23, two more groups appeared March 24, two more on March 25 and another two more on March 27.

The latest prediction from USAF/NOAA -- issued Thursday, March 31 -- differs from the one from the previous day. The March 30 prediction was referenced in The ARRL Letter, and the new prediction is less optimistic in terms of increasing solar activity. The March 31 projection shows solar flux at 115 on April 1-2, 110 on April 3-5, 105 on April 6-8, 100 on April 9-10. For April 11-17, we’ll see flux values of 95, 95, 90, 88, 88, 90 and 100. Then they show a rise to 125 on April 19-27, and 135 on April 28. The latest planetary A index projection shows 8 on April 1, 5 on April 2-7, 8 on April 8 and then back to 5 on April 9-17. Geophysical Institute Prague predicts quiet to unsettled conditions April 1, quiet April 2-4, quiet to unsettled April 5 and unsettled April 6-7.

Rob Steenburgh, KA8JBY, informs us of the annual Space Weather Workshop, April 26-29, 2011 in Boulder, Colorado. Rob also reminds us that there is “a nice web application for examining imagery from the SDO and SOHO spacecraft. It is called Helioviewer and can be found here. There’s also an open-source application folks can load on their computer called JHelioviewer. Users can create whole-disk animations, as well as movie loops zoomed in on active regions. They can also overlay various images. Both sites are open-source projects for the visualization of solar and heliospheric data. The projects are funded by ESA and NASA.”

I noticed that seems to work much better than when it was first announced. You can zoom in on the latest images, and also step back in time to see how the Sun has changed over the previous few hours, days or weeks.

Now that March has ended, we can review some sunspot number averages over previous months. The monthly averages for sunspot numbers -- December 2010 through March 2011 -- were 22, 32.2, 53.5 and 81.1. This represents a dramatic increase in solar activity. We’ve also been looking at a three-month moving average; the latest is for January 1 through March 31, centered on February. The three-month moving average centered on March 2010 through February 2011 was 22.3, 18.5, 16.4, 20.4, 23.2, 28.9, 33, 35.6, 31, 30.1, 35.3 and 55.7. So to review and clarify, 35.3 is the average for all daily sunspot numbers from December 1 through February 28, and 55.7 is the average of all sunspot numbers from January 1 through March 31.

Charles Tropp, N2SO, of Staten Island, New York, is excited about 10 meter propagation. He writes: “I saw a spot for 5N7M, Ivan, in Abuja, Nigeria on Monday, March 29 at 2000 on 28.009 CW, so I checked the frequency. Sure enough, there he was, loud and clear in Staten Island, New York. He was working US call areas 1, 2, 3, 4 and 5, none of which I could hear. So I gave him a call. He came right back to me, about 589. After I logged him, I decided to check my propagation program to see why this QSO was possible with my backyard vertical and my rig running 100 W. The effective SSN was about 72 at the time, KP was 1 and, yes, according to DX Atlas, there was a thin crescent moon-shaped propagation path running down Mexico and Central America, across the South Atlantic and just reaching Nigeria about 5230 miles from my location. All of the US was dark, which explains why I couldn’t hear any other signals. I just thought I would share my excitement.”

At first I was confused by Charles’ description of the propagation path, because this seemed an unlikely route for his signal to take. But he is probably talking about areas shown on the map that have propagation to Nigeria, which could be over a large area. You can see a nice photo of Charles and his station here. Click on the photo to zoom in.

Randy Crews, W7TJ, of Spokane, Washington, is excited about the increased solar activity and resulting HF propagation. He writes: “This past month has been the most amazing this year for high band propagation, as I am certain all DXers would agree for Solar Cycle 24. There have been more days with the solar flux topping 100 than below, in addition reaching a new high. Seventeen meters sounds like 20, and both 17 and 15 meters are loaded with DX stations from sunrise to well after sunset. Twelve meters has been extremely productive in the past few days, with European DX from 1500-2200Z! I have had QSOs stations not heard since 2001-02, as folks renew their interest. It really is great to see the high bands snap back after an incredibly long dry spell.”

Mike Shaffer, KA3JAW, of Tampa, Florida, sent in a link to some video recordings of broadcast television DX via tropospheric propagation from Cuba. This shows several stations received on Sunday, March 27.

Eric Bowen WK4CW, of Winston-Salem, North Carolina, sent in this report: “Just a report from the CQ WPX phone contest. Between 2200-2300 on March 27, I was able to work VK4RK and VK4MC, along with several JAs on 10 meters. I personally have not worked any Australians from the East Coast on 10 meters in quite a long time, and all were between 57 to 59 RST. I was running 100 W with an antenna 70 feet in the air. Conditions on all bands were good throughout the contest, and the flux at the time was 115, with the K and A indices both at 1. The SSN was 104.”

This report arrived on March 27: “I am Steve Moles, N5TEY, from Pawhuska, Oklahoma. I have read your propagation column weekly from the ARRL for years. I have always envied those operators you noted in your report who had worked the hard to find DX stations on an upper band. I was fortunate enough to catch one of those openings myself today. I had just came home from church and opened my BandMaster program and saw that VU2PAI (Ananth in Manglore, India) was working well into the US on 12 meters. I moved late last fall and only have up a Cushcraft MA5V (using RG-8X feed line) and am only running 250 W from my 746 Pro at this time. The past winter has been tough here and I am just now preparing to put up my tower for my hybrid cubical quad. The reports from the cluster reported Ananth as being a true 59 into the Southern US, so I thought I would give it a try.

“I turned on the rig and tuned to 24.965. VU2PAI was there, a true 59 at my home in Northern Oklahoma. I tuned my amplifier and gave a call up two (24.967) and Ananth replied to me on the first call as 59 into Southern India at 1613. I was so shocked I almost fell out of my chair! One of my daughters was in the room with me and she asked where the guy was I had just spoken with? She was amazed at how well he sounded. I had read last week about N8II reporting daily openings on 12 meters into Europe. I was able to experience the 12 meter opening today myself and still can hardly believe it.” Check out Steve’s site here.

Rich Dowty, W7EET, of St Paul, Oregon, notes that the DX Sherlock site also shows HF propagation maps, in addition to VHF. You can select HF and any continent to look at current conditions.

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.