Propagation Forecasts Delivered

There are a bunch of propagation forecasts available on the Net, but two are available as e-mail, delivered directly to you each week:

  1. Propagation de K7RA. This is the propagation bulletin broadcast by W1AW. The e-mail version is nice because it contains links to websites referenced by the report. To get the bulletin by e-mail, you have to be an ARRL member, but the bulletin is available for free on the ARRL website.
  2. KN4LF Radiowave Propagation Forecast. KN4LF has decided to freely distribute this once subscription-only forecast. This forecast is also available on the Web, but by signing up to get it by e-mail will ensure that you get it every week (on Thursday).

It’s Official! New Sunspot Cycle Has Started

NOAA: Sunspot is Harbinger of New Solar Cycle, Increasing Risk for Electrical Systems

January 4, 2008

First official sunspot belonging to the new Solar Cycle 24.

A new 11-year cycle of heightened solar activity, bringing with it increased risks for power grids, critical military, civilian and airline communications, GPS signals and even cell phones and ATM transactions, showed signs it was on its way late yesterday when the cycle’s first sunspot appeared in the sun’s Northern Hemisphere, NOAA scientists said.

“This sunspot is like the first robin of spring,” said solar physicist Douglas Biesecker of NOAA’s Space Weather Prediction Center. “In this case, it’s an early omen of solar storms that will gradually increase over the next few years.”

A sunspot is an area of highly organized magnetic activity on the surface of the sun. The new 11-year cycle, called Solar Cycle 24, is expected to build gradually, with the number of sunspots and solar storms reaching a maximum by 2011 or 2012, though devastating storms can occur at any time.

During a solar storm, highly charged material ejected from the sun may head toward Earth, where it can bring down power grids, disrupt critical communications, and threaten astronauts with harmful radiation. Storms can also knock out commercial communications satellites and swamp Global Positioning System signals. Routine activities such as talking on a cell phone or getting money from an ATM machine could suddenly halt over a large part of the globe.

“Our growing dependence on highly sophisticated, space-based technologies means we are far more vulnerable to space weather today than in the past,” said Vice Admiral Conrad C. Lautenbacher, Jr., under secretary of commerce for oceans and atmosphere and NOAA administrator. “NOAA’s space weather monitoring and forecasts are critical for the nation’s ability to function smoothly during solar disturbances.”

Last April, in coordination with an international panel of solar experts, NOAA issued a forecast that Solar Cycle 24 would start in March 2008, plus or minus six months. The panel was evenly split between those predicting a strong or weak cycle. Both camps agree that the sooner the new cycle takes over the waning previous cycle, the more likely that it will be a strong season with many sunspots and major storms, said Biesecker. Many more sunspots with Solar Cycle 24 traits must emerge before scientists consider the new cycle dominant, with the potential for more frequent storms.

The new sunspot, identified as #10,981, is the latest visible spot to appear since NOAA began numbering them on January 5, 1972. Its high-latitude location at 27 degrees North, and its negative polarity leading to the right in the Northern Hemisphere are clear-cut signs of a new solar cycle, according to NOAA experts. The first active regions and sunspots of a new solar cycle can emerge at high latitudes while those from the previous cycle continue to form closer to the equator.

SWPC is the nation’s first alert for solar activity and its affects on Earth. The center’s space weather forecasters issue outlooks for the next 11-year solar “season” and warn of individual storms occurring on the sun that could impact Earth. SWPC is one of NOAA’s nine National Centers for Environmental Prediction and is also the warning agency of the International Space Environment Service (ISES), a consortium of 11 member nations.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation’s coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

Yet More Guesses on the Next Sunspot Cycle

CNN reports that a government panel charged with forecasting the next sunspot cycle predict that

the current solar cycle will probably end next March, when Solar Cycle 24 will begin. That will mean Cycle 23 lasted 12 years, slightly longer than the usual 11-year cycle.

They are divided, however, on when the peak of the next cycle will occur. According to the report, “Half of the specialists predicted a moderately strong cycle of 140 sunspots expected to peak in October of 2011, while the rest called for a moderately weak cycle of 90 sunspots peaking in August of 2012.”

Read the complete story.

KQ6XA on How To Read HF Propagation Numbers

In my General Class license course, when I cover propagation, I often joke that the only index I use is the E-index. When I get a puzzled look, I explain that E stands for “ear,” and if I can hear stations that means propagation is good. If I can’t hear any stations, it means propagation is bad.

Seriously, though, it’s good to know what the various indexes mean. Here’s KQ6XA’s rules of thumb when it comes to interpreting the numbers.

  • K index: LOW is GOOD.
    • 0 or 1 is BEST
    • 2 is OK
    • 3 or more is BAD
    • 5 is VERY VERY BAD
  • A index: LOW is GOOD.
    • 1 to 6 is BEST
    • 7 to 9 is OK
    • 11 or more is BAD
  • Solar Flux Index: HIGH is GOOD.
    • 70 NOT GOOD
    • 80 GOOD
    • 90 BETTER
    • 100+ BEST

By the way, the Space Environment Center, a department of the NOAA, publishes the Radio User’s Page. This page provides links to space weather info specifically of interest to radio operators. Very cool.

Here Comes the Sun (doo doo doo doo)

Mike, K8XF, sent this link to this NASA news item about a prediction for the next peak in the sunspot cyle. According to Mausumi Dikpati of the National Center for Atmospheric Research (NCAR), “The next sunspot cycle will be 30% to 50% stronger than the previous one,” she says. If correct, the years ahead could produce a burst of solar activity second only to the historic Solar Max of 1958.”

Sounds good to me.

Solar Flares Cause GPS Failures, Cornell Researchers Warn

From the NARTE News, Winter 2007:

Cornell researchers have discovered that strong solar flares cause Global Positioning System (GPS) receivers to fail. Because solar flares are generally unpredictable, such failures could be devastating for “safety-of-life” GPS operations such as navigating passenger jets, stabilizing floating oil rigs and locating mobile phone distress calls.

“If you’re driving to the beach using your car’s navigation system, you’ll be OK. If you’re on a commercial airplane in zero visibility weather, maybe not,” says Paul Kintner Jr., professor of electrical and computer engineering at Cornell and head of Cornell’s GPS Laboratory.

Alessandro Cerruti, a graduate student working for Kintner, accidentally discovered the effect on while operating a GPS receiver at Arecibo Observatory in Puerto Rico, one of six Cornell Scintillation Monitor (SCINTMON) receivers. Cerruti was investigating irregularities in the plasma of the Earth’s ionosphere—a phenomenon unrelated to solar flares—when the flare occurred, causing the receiver’s signal to drop significantly.

To be sure of the effect, Cerruti obtained data from other receivers operated by the Federal Aviation Administration (FAA) and the Brazilian Air Force. He found that all the receivers had suffered exactly the same degradation at the exact time of the flare regardless of the manufacturer. Furthermore, all receivers on the sunlit side of the Earth had been affected.

The flare consisted of two events about 40 minutes apart. The first lasted 70 seconds and caused a 40% signal drop. The second lasted 15 minutes and caused a 50% drop. But this flare was moderate and short-lived; in 2011 and 2012, during the next solar maximum, flares are expected to be 10 times as intense and last much longer, causing signal drops of over 90% for several hours.

“Soon the FAA will require that every plane have a GPS receiver transmitting its position to air traffic controllers on the ground,” warns Cerruti. “But suppose one day you are on an aircraft and a solar radio burst occurs. There’s an outage, and the GPS receiver cannot produce a location. It’s a nightmare situation. But now that we know the burst’s severity, we might be able to mitigate the problem.”

The only solutions, suggests Kintner, are to equip receivers with weak signal-tracking algorithms or to increase the signal power from the satellites. Unfortunately, the former requires additional compromises to receiver design, and the latter requires a new satellite design that neither exists nor is planned.

“I think the best remedy is to be aware of the problem and operate GPS systems with the knowledge that they may fail during a solar flare,” says Kintner.

The team was initially confused as to why the flare had caused the signal loss. Then Kintner recalled that solar flares are accompanied by solar radio bursts. Because the bursts occur over the same frequency bands at which GPS satellites transmit, receivers can become confused, leading to a loss of signal. Had the solar flare occurred at night in Puerto Rico or had Cerruti been operating SCINTMON only at night, he would not have made the discovery.

“We normally do observations only in the tropics and only at night because that’s where and when the most intense ionospheric irregularities occur,” says Kintner. However, since no one had done it before, Cerruti was looking at “mid-latitudes” (between the tropics and the poles), where weaker irregularities can occur both night and day. As a result, SCINTMON detected the solar flare.

Cerruti reported the findings on September 28 at the Institute of Navigation Meeting in Fort Worth, Texas, where he received the best student paper prize. The full results of the discovery will be published in a forthcoming issue of Space Weather. O t h e r authors of the paper include D.E. Gary and L.J. Lanzerotti of the New Jersey Institute of Technology, E.R. de Paula of the Instituto Nacional de Pesquisas Espaciais and Cornell research associate Hien Vo.

Next Solar Cycle Could Be a Big One

From the Science@NASA website:

Evidence is mounting: the next solar cycle is going to be a big one.

Solar cycle 24, due to peak in 2010 or 2011 “looks like its going to be one of the most intense cycles since record-keeping began almost 400 years ago,” says solar physicist David Hathaway of the Marshall Space Flight Center. He and colleague Robert Wilson presented this conclusion last week at the American Geophysical Union meeting in San Francisco.


Sunspots? We Don’t Need No Steenkin’ Sunspots!

Last night, at the ARROW meeting, George K9TRV was a last-minute replacement for our scheduled speaker, who, apparently, had gotten into a poison ivy patch over the weekend. George showed us a couple of websites and demonstrated some propagation software he’s been using. I’d say the results speak for themselves. George has worked 120 countries in little over a year.

Here are the links to the websites and software:

  • William Hepburn’s Radio & TV DX Information Centre. Most interesting for 50MHz and 144MHz sporadic E skip prediction. Got this one from Steve Andre, WB8WSF. Free.
  • DXWatch.Com. You can submit your own spots as well. Catches the packet cluster DX spotting data for internet use. Has stock and custom filters. Free.
  • DX Atlas. Home for the DX Atlas software, including DX Atlas, BandMaster, IonoProbe and HamCap. BandMaster will control your radio. IonoProbe fetches the current sunspot data, Ap, Kp, auroral data, Proton and Xray intensity, and feeds to HamCap. HamCap uses IonoProbe data and the VoaCap engine to predict HF propagation, MUF and other data. Shows sun location, greyline and propagation forecast. Propagation data can be pushed to DXAtlas. You can specify your antenna situation to get more accurate info. Can specify your own antenna with EZNEC output data. DXAtlas shows either ITU or CQ regions of the world, can show the spots and spotters from BandMaster, as well as the short or long path. Can show beam headings for short or long path. Has a UTC clock built in. 30 day trial version. $60 for package of all 4 programs.

Sun’s next 11-year cycle could be 50 pct stronger

From Reuters via Yahoo

By Deborah Zabarenko
Mon Mar 6, 3:49 PM ET

Sun-spawned cosmic storms that can play havoc with earthly power grids and orbiting satellites could be 50 percent stronger in the next 11-year solar cycle than in the last one, scientists said on Monday.

Using a new model that takes into account what happens under the sun’s surface and data about previous solar cycles, astronomers offered a long-range forecast for solar activity that could start as soon as this year or as late as 2008.

They offered no specific predictions of solar storms, but they hope to formulate early warnings that will give power companies, satellite operators and others on and around Earth a few days to prepare.

“This prediction of an active solar cycle suggests we’re potentially looking at more communications disruptions, more satellite failures, possible disruptions of electrical grids and blackouts, more dangerous conditions for astronauts,” said Richard Behnke of the Upper Atmosphere Research Section at the National Science Foundation.

“Predicting and understanding space weather will soon be even more vital than ever before,” Behnke said at a telephone news briefing.

The prediction, roughly analogous to the early prediction of a severe hurricane season on Earth, involves the number of sunspots on the solar surface, phenomena that have been monitored for more than a century.


Every 11 years or so, the sun goes through an active period, with lots of sunspots. This is important, since solar storms — linked to twisted magnetic fields that can hurl out energetic particles — tend to occur near sunspots.

The sun is in a relatively quiet period now, but is expected to get more active soon, scientists said. However, there is disagreement as to whether the active period will start within months — late 2006 or early 2007 — or years, with the first signs in late 2007 or early 2008.

Whenever it begins, the new forecasting method shows sunspot activity is likely to be 30 percent to 50 percent stronger than the last active period. The peak of the last cycle was in 2001, the researchers said, but the period of activity can span much of a decade.

The strongest solar cycle in recent memory occurred in the late 1950s, when there were few satellites aloft, no astronauts in orbit and less reliance on electrical power grids than there is now.

If a similarly active period occurred now, the impact would be hard to predict, according to Joseph Kunches of the National Oceanic & Atmospheric Administration’s Space Environment Center in Colorado.

“It’s pretty uncertain what would happen, which makes this work more relevant,” Kunches said.

“What we have here is a prediction that the cycle is going to be very active, and what we need and what we’re of course working on is to be able to predict individual storms with a couple days or hours in advance so the grids can take the action,” Behnke said.

FREE Propagation Software

Here’s a great resource for amateur radio operators. The best thing about it is that it’s free! Unfortunately, it only runs on PCs, but since the FORTRAN source code is also free, perhaps I can figure out a way to adapt it to the Mac.

VOACAP is a free professional HF prediction program from NTIA/ITS, originally developed for Voice of America (VOA) and is the result of 50+ years of U.S. HF research and development. Considered by many to be the most professional HF system performance prediction tool available, VOA and a number of other international HF broadcasters and institutions all over the world currently use it for HF frequency planning.

Features include:

  • Easy to use graphical user interface and, for advanced users, powerful command line options
  • Detailed Point-to-Point graphs and Area Coverage maps for 22 parameters of circuit quality such as:
    • SNR (Signal-to-Noise Ratio)
    • Reliability
    • Required Power Gain
    • Signal Power
    • MUF
    • Takeoff/Arrival Angle, and more
  • Accurate predictions of the distribution of Worldwide Atmospheric and Man-made radio noise using the latest ITU-R recommendations and a unique combination methodology developed by the late A. D. Spaulding, a world authority in the modeling of noise distributions
  • Detailed hourly and 24-hour predictions for the entire HF spectrum [2 to 30 MHz] with user assigned frequencies, such as:
    • Point-to-Point Performance vs Distance at the given hour for the given parameter at one or all user assigned frequencies
    • Point-to-Point Performance vs Time for the given parameter at one or all user assigned frequencies on the 24-hour scale
  • User defined circuit databases for repeated or batch calculations
  • Thirty calculation Methods for:
    • ionograms
    • antenna patterns
    • complete system performance
  • Versatile coverage maps: one transmitter to many receivers [VOAAREA], or many transmitters to one receiver [VOAAREA Inverse] for bi-directional circuit studies
  • Freely adjustable geographical maps to be plotted on
  • Adjustable precision in coverage map calculations
  • Huge databases of more than 35,000 U.S. and world locations, including DXCC, NCDXF beacons, and HF broadcasting stations, to name a few
  • Accepts unlimited number of user defined location databases
    Database of hundreds of transmit and receive antennas, with ability to user adjustments using HFANT, for:
    • amateur radio
    • broadcasting
    • SWL, and more
  • Accepts unlimited number of user defined antenna files (HFANT and Type 11 & 13)
  • Comprehensive, user-community supported online VOACAP Quick Guide available for beginners and advanced users
  • FORTRAN source code freely available for the prediction module of VOACAP [VOACAPW]
  • Not subject to copyright protection in the U.S.
  • Available for free downloading from the U.S. Department of Commerce (NTIA/Institute for Telecommunication Sciences; Boulder, Colorado).