The K7RA Solar Update


Recent days graced by sunspots were short lived. June 10-June 13 saw a single sunspot group, followed by two days with no spots then a week of spots from June 16-22. During that week, the sunspot number was 11 every day, the lowest non-zero sunspot number. The four days since have had no spots at all. All the sunspot numbers for the last calendar quarter are listed here. This current quarter data is only available on the net through June 30. July 1 begins a new quarter.

This weekend is ARRL Field Day, and while there are no sunspots, E skip is a possibility and conditions should be quiet, meaning no geomagnetic disturbance is expected. Predicted planetary A index for June 27-July 3 is predicted at 10, 8, 5, 5, 5, 5 and 5. Geophysical Institute Prague expects unsettled conditions June 27-28, quiet to unsettled June 29 and quiet June 30 to July 3. Sunspot numbers for June 19 through 25 were 11, 11, 11, 11, 0, 0 and 0 with a mean of 6.3. The 10.7 cm flux was 64.9, 65.2, 64.8, 65.4, 65.3, 65.8 and 65.9 with a mean of 65.3. Estimated planetary A indices were 6, 11, 5, 4, 3, 4 and 12 with a mean of 6.4. Estimated mid-latitude A indices were 5, 8, 4, 2, 2, 3 and 10 with a mean of 4.9.

Ken Standard, AD5XJ, of Houma, Louisiana wrote "I have been tracking the NOAA dynamic indicators available here. While I see that if everything is in the green areas, that is better than when they are in the yellow or red areas. My problem is figuring out what indication each has for HF propagation specifically. The available data on these indicators is scarce and ambiguous at best. Can you enlighten me?"

The first figure, the Magnetic Field Bz component, relates to the IMF, or Interplanetary Magnetic Field that we've mentioned in past bulletins. When it is pointing north relative to Earth, this provides a kind of shield against solar wind, and Earth is less likely to experience geomagnetic activity. When it points south, the Earth is vulnerable. The scale in this figure is marked green at one end, indicating the most protection, and red at the other end, representing the greater likelihood of geomagnetic activity. The next two figures, Speed and Dynamic Pressure, express the speed and pressure currently from solar wind. Similarly, the scales run from green to red signifying their relationship to geomagnetic disturbance.

We've had news of recent E-layer propagation on 6 and 10 meters, and Tom Scorr, AD5FD, of Shertz, Texas, wrote to us about 2 meter sporadic E and an opening Sunday morning of the recent VHF contest. Running 100 W to a dual band ground plane on SSB, he worked three grids in Minnesota and two in Wisconsin. He is in EL09, and said this went on for an hour with very loud signals. One station was 20 dB over S9.

Neal Sulmeyer, K4EA, of Canton, Georgia, said on June 13 from 2300-2345 UTC, he worked 17 Japanese stations on 6 meters from EM74. He wrote: "My best guess is that this was multi-hop E-skip as there was no aurora and the SFI was in the mid 60s. I have asked several of the long time 6 meter operators in the area, and there is agreement that this is the first time that JAs have been worked from north Georgia on E-skip."

Todd Phillips, N4QWZ, of Greenbrier, Tennessee, had a blast on 2 meters in the recent VHF contest. He is in EM66ok, and says WA7JTM was his longest distance 2 meter contact, at 1278 miles. He worked KB0HH (EM06) on both 144 and 432 MHz via tropo at 685 miles. He wrote, "To top the day off, on 6 meters as I was working a pile of 1s and 2s, EA8BPX (IL18) called me (4034 miles). The best June contest ever!"

Pat Dyer, WA5IYX, of San Antonio, Texas, sent a link to audio of National Weather Service station KXI68 on 162.45 in Iowa, 1011 miles away. This was on Sunday morning during the VHF contest, and you can hear the audio file. He used an 11 element 6 meter Yagi mounted six feet above ground, and worked mostly into Iowa and Minnesota. You can listen to him here working Japan on 6 meter CW.

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 in The ARRL Letter. Check 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.