Propagation Summary
The Solar Flux has actually hit the 100 mark in mid February, but had dropped back to 80 by the beginning of March. The Solar Flux should rise to 95 by mid March. The Boulder A index peaked at 25 on the 18th February, dropping back to 5 by the 20th then after peaking at 10 at the beginning of March, it should settle back to the ‘norm’ of 5. The Boulder K Index seems to be the best indicator of SW conditions. If it reaches 5 (like on February 18th) conditions are usually disturbed but, if it drops down to 2, conditions are generally steady. A 24 day forecast can be found at: http://www.wm7d.net/hamradio/solar/27d_forecast.shtml
The Solar flux trend charts at www.solarcycle24.com/flares.htm show that the dip in progress during mid 2010 has recovered but numbers are still well below predicted levels. The Solar flux would need to be averaging at around 110 to reach it’s predicted peak in the first quarter of 2013. There were 260 spotless days in 2009 (70%) compared with just 51 in 2010 (14%).
First X-flare of the New Solar Cycle Earth-orbiting satellites have detected the strongest solar flare in more than four years. At 0156 UT on Feb. 15th, giant sunspot 1158 unleashed an X2-class eruption. X-flares are the strongest type of x-ray flare, and this is the first such eruption of new Solar Cycle 24. The explosion that produced the flare also sent a solar tsunami rippling through the sun's atmosphere and, more importantly, hurled a coronal mass ejection toward Earth. This is likely to have caused the disturbance on February 18th. A Radio Blackout Indicator can be found at www.solarcycle24.com as well as pictures and video of solar activity.
Sunspot Data (Royal Greenwich Observatory)
Sunspots appear as dark spots on the surface of the Sun. They typically last for several days, although very large ones may live for several weeks. Sunspots are magnetic regions on the Sun with magnetic field strengths thousands of times stronger than the Earth's magnetic field. Sunspots usually come in groups with two sets of spots. One set will have positive or north magnetic field while the other set will have negative or south magnetic field. The field is strongest in the darker parts of the sunspots - the umbra. The field is weaker and more horizontal in the lighter part - the penumbra.
The Royal Greenwich Observatory (RGO) compiled sunspot observations from a small network of observatories to produce a data set of daily observations starting in May of 1874. The observatory concluded this data set in 1976 after the US Air Force (USAF) started compiling data from its own Solar Optical Observing Network (SOON). This work was continued with the help of the US National Oceanic and Atmospheric Administration (NOAA) with much of the same information being compiled through to the present. Unfortunately, the more recent data is given in a different format from the original and there are definite changes in the reported parameters from the different sources. In an effort to append the RGO data with the more recent data I have reformatted the USAF and NOAA data to conform to the older RGO data format. The entire data set is available below as ASCII text files containing records for individual years. Each file consists of records with information on individual sunspot groups for each day that spots were observed. The series of data files from 1874-2004 are also available in a single 5.1 Mb ZIP file at: http://solarscience.msfc.nasa.gov/greenwch/RGO_NOAA1874_2004.zip .
Solar Activity MonitorA Solar Activity Monitor can be found at: http://www.n3kl.org/sun/status.html . If you have a website, you can also display the monitor on your web pages.
Acknowledgements to Mike Terry and Ken Fletcher for articles and updates.
Saturday, 26 February 2011
Monday, 31 January 2011
February 2011
Propagation Summary During January conditions have remained steady and February should remain the same with the Solar Flux mainly at 82. Apart from a slight fluctuation around 3rd February, the Boulder A index is likely to stay at 5 and the K index at 2. www.wm7d.net/hamradio/solar/27d_forecast.shtml
NASA Sun Spot Number predictions revised yet again.
NASA has revised their Sun Spot prediction once again and it is now at the level of the Maunder Minimum of 1675 -1715 when the climate was much colder. The solar cycle 24 predicted sunspot maximum has been reduced again – predicted peak down to 59 Max. Current prediction for the next sunspot cycle maximum gives a smoothed sunspot number maximum of about 59 in June/July of 2013. We are currently two years into Cycle 24 and the predicted size continues to fall. (NASA Solar Physics, 3 January 2011. http://solarscience.msfc.nasa.gov/predict.shtml )
Cycle 24 Continues “During the course of an approximate eleven year sunspot cycle, the minimum phase, or quiet sun, is generally considered to exist during the time when the smoothed sunspot number (SSN) drops, and remains below 30. The smoothed sunspot number is a monthly index compiled by the Royal Observatory of Belgium for measuring solar cycle progress.
An unbroken string of smoothed sunspot numbers has been recorded since 1750. The present period of quiet sun began as declining Cycle 23 dropped below the SSN 30 level during April, 2005. A period of moderate solar activity is expected for the remainder of 2011, reaching a sunspot count on the order of 60 by year's end. This six-year solar quiet period was the deepest and most persistent recorded in almost two hundred years. It mystified solar scientists, and it is another example of how little is yet known about sunspots and of the nature of the Sun itself.” (George Jacobs WRTH 2011)
Say Goodbye To Sunspots ?“Scientists studying sunspots for the past 2 decades have concluded that the magnetic field that triggers their formation has been steadily declining. If the current trend continues, by 2016 the sun's face may become spotless and remain that way for decades—a phenomenon that in the 17th century coincided with a prolonged period of cooling on Earth.
The last solar minimum should have ended last year, but something peculiar has been happening. Although solar minimums normally last about 16 months, the current one has stretched over 26 months—the longest in a century. One reason, according to a paper submitted to the International Astronomical Union Symposium No. 273, an online colloquium, is that the magnetic field strength of sunspots appears to be waning. “
( http://news.sciencemag.org/sciencenow/2010/09/say-goodbye-to-sunspots.html )
Sunspots may vanish by 2015. By William Livingston, and Matthew Penn.
“We have observed spectroscopic changes in temperature sensitive molecular lines, in the magnetic splitting of an Fe I line, and in the continuum brightness of over 1000 sunspot umbrae from 1990-2005. All three measurements show consistent trends in which the darkest parts of the sunspot umbra have become warmer (45K per year) and their magnetic field strengths have decreased (77 Gauss per year), independently of the normal 11-year sunspot cycle. A linear extrapolation of these trends suggests that few sunspots will be visible after 2015.”
This article can be viewed in PDF format at: http://wattsupwiththat.files.wordpress.com/2008/06/livingston-penn_sunspots2.pdf
Thanks to Ken Fletcher and Mike Terry for this month’s articles. Links to these articles can be found at: www.jameswelsh.org.uk
NASA Sun Spot Number predictions revised yet again.
NASA has revised their Sun Spot prediction once again and it is now at the level of the Maunder Minimum of 1675 -1715 when the climate was much colder. The solar cycle 24 predicted sunspot maximum has been reduced again – predicted peak down to 59 Max. Current prediction for the next sunspot cycle maximum gives a smoothed sunspot number maximum of about 59 in June/July of 2013. We are currently two years into Cycle 24 and the predicted size continues to fall. (NASA Solar Physics, 3 January 2011. http://solarscience.msfc.nasa.gov/predict.shtml )
Cycle 24 Continues “During the course of an approximate eleven year sunspot cycle, the minimum phase, or quiet sun, is generally considered to exist during the time when the smoothed sunspot number (SSN) drops, and remains below 30. The smoothed sunspot number is a monthly index compiled by the Royal Observatory of Belgium for measuring solar cycle progress.
An unbroken string of smoothed sunspot numbers has been recorded since 1750. The present period of quiet sun began as declining Cycle 23 dropped below the SSN 30 level during April, 2005. A period of moderate solar activity is expected for the remainder of 2011, reaching a sunspot count on the order of 60 by year's end. This six-year solar quiet period was the deepest and most persistent recorded in almost two hundred years. It mystified solar scientists, and it is another example of how little is yet known about sunspots and of the nature of the Sun itself.” (George Jacobs WRTH 2011)
Say Goodbye To Sunspots ?“Scientists studying sunspots for the past 2 decades have concluded that the magnetic field that triggers their formation has been steadily declining. If the current trend continues, by 2016 the sun's face may become spotless and remain that way for decades—a phenomenon that in the 17th century coincided with a prolonged period of cooling on Earth.
The last solar minimum should have ended last year, but something peculiar has been happening. Although solar minimums normally last about 16 months, the current one has stretched over 26 months—the longest in a century. One reason, according to a paper submitted to the International Astronomical Union Symposium No. 273, an online colloquium, is that the magnetic field strength of sunspots appears to be waning. “
( http://news.sciencemag.org/sciencenow/2010/09/say-goodbye-to-sunspots.html )
Sunspots may vanish by 2015. By William Livingston, and Matthew Penn.
“We have observed spectroscopic changes in temperature sensitive molecular lines, in the magnetic splitting of an Fe I line, and in the continuum brightness of over 1000 sunspot umbrae from 1990-2005. All three measurements show consistent trends in which the darkest parts of the sunspot umbra have become warmer (45K per year) and their magnetic field strengths have decreased (77 Gauss per year), independently of the normal 11-year sunspot cycle. A linear extrapolation of these trends suggests that few sunspots will be visible after 2015.”
This article can be viewed in PDF format at: http://wattsupwiththat.files.wordpress.com/2008/06/livingston-penn_sunspots2.pdf
Thanks to Ken Fletcher and Mike Terry for this month’s articles. Links to these articles can be found at: www.jameswelsh.org.uk
Thursday, 30 December 2010
January 2011
Propagation Summary
Sunspot numbers have progressively dropped since 2002 with the lowest numbers recorded in 2008. However, since 2009 there has been a upward trend but the Solar Flux progression charts at http://solarcycle24.com/flux.htm still show the sunspot numbers to be consistently lower than predicted. There are more historical charts at: http://wm7d.net/hamradio/solar/historical.shtml
January’s Solar activity is predicted to be on yet another downward trend. The Solar Flux is forecast to drop from 90 to 80 during January. The Boulder A index will stay at 5, except for 4 - 6 and 20 - 21 January. The Boulder A index is likely to remain at a steady 2 for this period.
Global Eruption Rocks the Sun
On August 1, 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, billion-ton clouds of hot gas billowed into space. "The August 1st event really opened our eyes," says Karel Schrijver of Lockheed Martin's Solar and Astrophysics Lab in Palo Alto, CA. "We see that solar storms can be global events, playing out on scales we scarcely imagined before." "The whole-sun approach could lead to breakthroughs in predicting solar activity," commented Rodney Viereck of NOAA's Space Weather Prediction Centre in Boulder, CO. "To predict eruptions we can no longer focus on the magnetic fields of isolated active regions," says Title, "we have to know the surface magnetic field of practically the entire sun." This revelation increases the work load for space weather forecasters, but it also increases the potential accuracy of their forecasts
(NASA Science News. 6 December 2010).
NASA Solar Shield Project
Solar storms don’t just affect radio propagation. Every hundred years or so, a solar storm comes along so potent it fills the skies of Earth with blood-red auroras, makes compass needles point in the wrong direction, and sends electric currents coursing through the planet's topsoil. The most famous such storm, the Carrington Event of 1859, actually shocked telegraph operators and set some of their offices on fire. A 2008 report by the National Academy of Sciences warns that if such a storm occurred today, we could experience widespread power blackouts with permanent damage to many key transformers. Solar Shield is a new and experimental forecasting system for the North American power grid," explains project leader Antti Pulkkinen, a Catholic University of America research associate working at NASA's Goddard Space Flight Centre. "We believe we can zero in on specific transformers and predict which of them are going to be hit hardest by a space weather event."
The troublemaker for power grids is the "GIC" – short for geomagnetically induced current. When a coronal mass ejection (a billion-ton solar storm cloud) hits Earth's magnetic field, the impact causes the field to shake and quiver. These magnetic vibrations induce currents almost everywhere, from Earth's upper atmosphere to the ground beneath our feet. Powerful GICs can overload circuits, trip breakers, and in extreme cases melt the windings of heavy-duty transformers.
This actually happened in Quebec on March 13, 1989, when a geomagnetic storm much less severe than the Carrington Event knocked out power across the entire province for more than nine hours. The storm damaged transformers in Quebec, New Jersey, and Great Britain, and caused more than 200 power anomalies across the USA from the eastern seaboard to the Pacific Northwest. A similar series of storms in October 2003 triggered a regional blackout in southern Sweden and may have damaged transformers in South Africa. Pulkkinen stresses that Solar Shield is experimental and has never been field-tested during a severe geomagnetic storm.
“The more data we can collect from the field, the faster we can test and improve Solar Shield. The next solar maximum is expected around 2013, so it's only a matter of time.“ Full article at: http://science.nasa.gov/science-news/science-at-nasa/2010/26oct_solarshield/
Sunspot numbers have progressively dropped since 2002 with the lowest numbers recorded in 2008. However, since 2009 there has been a upward trend but the Solar Flux progression charts at http://solarcycle24.com/flux.htm still show the sunspot numbers to be consistently lower than predicted. There are more historical charts at: http://wm7d.net/hamradio/solar/historical.shtml
January’s Solar activity is predicted to be on yet another downward trend. The Solar Flux is forecast to drop from 90 to 80 during January. The Boulder A index will stay at 5, except for 4 - 6 and 20 - 21 January. The Boulder A index is likely to remain at a steady 2 for this period.
Global Eruption Rocks the Sun
On August 1, 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, billion-ton clouds of hot gas billowed into space. "The August 1st event really opened our eyes," says Karel Schrijver of Lockheed Martin's Solar and Astrophysics Lab in Palo Alto, CA. "We see that solar storms can be global events, playing out on scales we scarcely imagined before." "The whole-sun approach could lead to breakthroughs in predicting solar activity," commented Rodney Viereck of NOAA's Space Weather Prediction Centre in Boulder, CO. "To predict eruptions we can no longer focus on the magnetic fields of isolated active regions," says Title, "we have to know the surface magnetic field of practically the entire sun." This revelation increases the work load for space weather forecasters, but it also increases the potential accuracy of their forecasts
(NASA Science News. 6 December 2010).
NASA Solar Shield Project
Solar storms don’t just affect radio propagation. Every hundred years or so, a solar storm comes along so potent it fills the skies of Earth with blood-red auroras, makes compass needles point in the wrong direction, and sends electric currents coursing through the planet's topsoil. The most famous such storm, the Carrington Event of 1859, actually shocked telegraph operators and set some of their offices on fire. A 2008 report by the National Academy of Sciences warns that if such a storm occurred today, we could experience widespread power blackouts with permanent damage to many key transformers. Solar Shield is a new and experimental forecasting system for the North American power grid," explains project leader Antti Pulkkinen, a Catholic University of America research associate working at NASA's Goddard Space Flight Centre. "We believe we can zero in on specific transformers and predict which of them are going to be hit hardest by a space weather event."
The troublemaker for power grids is the "GIC" – short for geomagnetically induced current. When a coronal mass ejection (a billion-ton solar storm cloud) hits Earth's magnetic field, the impact causes the field to shake and quiver. These magnetic vibrations induce currents almost everywhere, from Earth's upper atmosphere to the ground beneath our feet. Powerful GICs can overload circuits, trip breakers, and in extreme cases melt the windings of heavy-duty transformers.
This actually happened in Quebec on March 13, 1989, when a geomagnetic storm much less severe than the Carrington Event knocked out power across the entire province for more than nine hours. The storm damaged transformers in Quebec, New Jersey, and Great Britain, and caused more than 200 power anomalies across the USA from the eastern seaboard to the Pacific Northwest. A similar series of storms in October 2003 triggered a regional blackout in southern Sweden and may have damaged transformers in South Africa. Pulkkinen stresses that Solar Shield is experimental and has never been field-tested during a severe geomagnetic storm.
“The more data we can collect from the field, the faster we can test and improve Solar Shield. The next solar maximum is expected around 2013, so it's only a matter of time.“ Full article at: http://science.nasa.gov/science-news/science-at-nasa/2010/26oct_solarshield/
Saturday, 23 October 2010
November 2010
Propagation Summary
Conditions have remained fairly steady during October. The solar Flux actually reached 90 on the 20th, but it should fall to 75 by November 1st then rise again to 85 by mid November. The Boulder A index should stay at 5 and the K index at 2 during the first half of November. So far during 2010, there have been 45 spotless days (15%) , compared 260 in 2009 (71%). http://www.wm7d.net/hamradio/solar/27d_forecast.shtml )
Meteor Showers
Earth is passing through a stream of debris from Halley's Comet, and this is causing the annual Orionid meteor shower. Bright moonlight is reducing the number of visible meteors; nevertheless, sky watchers are reporting some bright Orionids.
Meteor showers provide a very significant increase in the number of meteor trails that can be used for radio communications. These showers arrive at fixed times of the year, appearing on an annual basis. Some are small, whereas others are much larger and can last for several days. There are hundreds or possibly even thousands of these showers. The smaller showers are not easy to distinguish, but some of the larger showers produce a spectacular display if their occurrence coincides with a clear night.
When a meteor shower is observed it will be seen that the meteors appear to come from a single point in the sky which is known as the "radiant". This is a perspective effect caused by the fact that all the particles enter the Earth's atmosphere parallel to one another. The radiant gives rise to the name of the shower - the Perseids shower has its radiant in the constellation of Perseus.
Showers are caused by groups of particles orbiting the Sun in an elliptical orbit. Usually they are associated with comets which leave their debris behind them. Although not all meteor showers have been linked to particular comets, it is thought that all showers come from this source.
Showers vary in intensity from one year to the next. This happens because the particles are not evenly spread around their orbit. One of the most reliable and constant showers is the Perseids shower, but even this one shows some significant variations from one year to the next.
Meteor showers forecast for November are:
Taurids from 25 October to 25 November peaking on November 4th. Leonids: 15 - 19 November peaking on the 17th. Cephids 7 - 9 November peaking on the 11th More details at: http://surf.to/meteorscatter See also: http://stardate.org/nightsky/meteors and: www.spaceweather.com (Via Mike Terry)
DX Info Centre
Here is a website all about FM and UHF DX’ing. Subjects covered included are Tropospheric Ducting and E Skip. There are also many world maps showing colour coded event forecasts, plus links to other relevant websites: www.dxinfocentre.com/
Links to these articles and more can be found at: www.jameswelsh.org.uk
Conditions have remained fairly steady during October. The solar Flux actually reached 90 on the 20th, but it should fall to 75 by November 1st then rise again to 85 by mid November. The Boulder A index should stay at 5 and the K index at 2 during the first half of November. So far during 2010, there have been 45 spotless days (15%) , compared 260 in 2009 (71%). http://www.wm7d.net/hamradio/solar/27d_forecast.shtml )
Meteor Showers
Earth is passing through a stream of debris from Halley's Comet, and this is causing the annual Orionid meteor shower. Bright moonlight is reducing the number of visible meteors; nevertheless, sky watchers are reporting some bright Orionids.
Meteor showers provide a very significant increase in the number of meteor trails that can be used for radio communications. These showers arrive at fixed times of the year, appearing on an annual basis. Some are small, whereas others are much larger and can last for several days. There are hundreds or possibly even thousands of these showers. The smaller showers are not easy to distinguish, but some of the larger showers produce a spectacular display if their occurrence coincides with a clear night.
When a meteor shower is observed it will be seen that the meteors appear to come from a single point in the sky which is known as the "radiant". This is a perspective effect caused by the fact that all the particles enter the Earth's atmosphere parallel to one another. The radiant gives rise to the name of the shower - the Perseids shower has its radiant in the constellation of Perseus.
Showers are caused by groups of particles orbiting the Sun in an elliptical orbit. Usually they are associated with comets which leave their debris behind them. Although not all meteor showers have been linked to particular comets, it is thought that all showers come from this source.
Showers vary in intensity from one year to the next. This happens because the particles are not evenly spread around their orbit. One of the most reliable and constant showers is the Perseids shower, but even this one shows some significant variations from one year to the next.
Meteor showers forecast for November are:
Taurids from 25 October to 25 November peaking on November 4th. Leonids: 15 - 19 November peaking on the 17th. Cephids 7 - 9 November peaking on the 11th More details at: http://surf.to/meteorscatter See also: http://stardate.org/nightsky/meteors and: www.spaceweather.com (Via Mike Terry)
DX Info Centre
Here is a website all about FM and UHF DX’ing. Subjects covered included are Tropospheric Ducting and E Skip. There are also many world maps showing colour coded event forecasts, plus links to other relevant websites: www.dxinfocentre.com/
Links to these articles and more can be found at: www.jameswelsh.org.uk
Thursday, 23 September 2010
October 2010
Propagation Summary
Conditions have remained fairly steady during September. October should begin quiet apart from a slight disturbance on the 5th and the 12th . The Boulder A index is peaking at around 10 every 7 days, and the K index is varying between 2 and 3 during these peaks. Sunspot numbers have remained around the 80 mark during August and September. October should remain the same. According to the trend charts at Solar Cycle 24.com, the Solar flux is forecast to reach 100 by the end of 2010, but after a drop in mid 2010, numbers have continued to remain at around 80 and if this trend continues, it will not reach the predicted peak of 140 by 2014.
Solar Storms can Change Directions, Surprising Forecasters
Solar storms don't always travel in a straight line. But once they start heading in our direction, they can accelerate rapidly, gathering steam for a harder hit on Earth's magnetic field.
So say researchers who have been using data from NASA's twin STEREO spacecraft to unravel the 3D structure of solar storms.
Their findings are presented in Nature Communications. Magazine "This really surprised us," says co-author Peter Gallagher of Trinity College in Dublin. "Solar coronal mass ejections (CMEs) can start out going one way—and then turn in a different direction." The result was so strange, at first they thought they'd done something wrong. After double- and triple-checking their work on dozens of eruptions, however, the team knew they were onto something. The sun's global magnetic field, which is shaped like a bar magnet, guides the wayward CMEs back toward the sun's equator. When the clouds reach low latitudes, they get caught up in the solar wind and head out toward the planets—"like a cork bobbing along a
river," says Gallagher. (NASA Science News 21 September 2010)
Solar Probe to Plunge Directly into Sun's Atmosphere
NASA's plan to visit the sun took a leap forward today with the selection of five key science investigations for the Solar Probe spacecraft. Slated to launch no later than 2018, the smart car-sized spacecraft will plunge directly into the atmosphere of the sun, aiming to solve some of the biggest mysteries of solar physics. This means that researchers can begin building sensors for ‘in situ’ measurements of the solar system's innermost frontier. Lika Guhathakurta, NASA Solar Probe Programme scientist said: "For the first time, we'll be able to 'touch, taste and smell' the sun." Last year, NASA invited top researchers around the world to submit proposals detailing possible science investigations for the pioneering spacecraft. More details at: NASA Science News
About Sunspot Cycles
Dark spots appear at places on the Sun where its magnetic field is concentrated. The number of sunspots is controlled by the amount of distortion of the Sun's magnetic field. The magnetic field becomes distorted because the Sun's equator and core rotate more quickly than its other parts. As a result, sunspot activity varies over an average 11-year cycle. During this period, the Sun goes from a solar minimum (fewer spots) to a solar maximum (more spots) and back to a minimum again. The solar magnetic activity cycle is the main source of the ~10.7 year periodic solar variation, which drives variations in space weather and to some degree weather on the ground and possibly climate change. (BBC article via Ken Fletcher)
Thanks to Ken Fletcher and Mike Terry for regular updates.
Conditions have remained fairly steady during September. October should begin quiet apart from a slight disturbance on the 5th and the 12th . The Boulder A index is peaking at around 10 every 7 days, and the K index is varying between 2 and 3 during these peaks. Sunspot numbers have remained around the 80 mark during August and September. October should remain the same. According to the trend charts at Solar Cycle 24.com, the Solar flux is forecast to reach 100 by the end of 2010, but after a drop in mid 2010, numbers have continued to remain at around 80 and if this trend continues, it will not reach the predicted peak of 140 by 2014.
Solar Storms can Change Directions, Surprising Forecasters
Solar storms don't always travel in a straight line. But once they start heading in our direction, they can accelerate rapidly, gathering steam for a harder hit on Earth's magnetic field.
So say researchers who have been using data from NASA's twin STEREO spacecraft to unravel the 3D structure of solar storms.
Their findings are presented in Nature Communications. Magazine "This really surprised us," says co-author Peter Gallagher of Trinity College in Dublin. "Solar coronal mass ejections (CMEs) can start out going one way—and then turn in a different direction." The result was so strange, at first they thought they'd done something wrong. After double- and triple-checking their work on dozens of eruptions, however, the team knew they were onto something. The sun's global magnetic field, which is shaped like a bar magnet, guides the wayward CMEs back toward the sun's equator. When the clouds reach low latitudes, they get caught up in the solar wind and head out toward the planets—"like a cork bobbing along a
river," says Gallagher. (NASA Science News 21 September 2010)
Solar Probe to Plunge Directly into Sun's Atmosphere
NASA's plan to visit the sun took a leap forward today with the selection of five key science investigations for the Solar Probe spacecraft. Slated to launch no later than 2018, the smart car-sized spacecraft will plunge directly into the atmosphere of the sun, aiming to solve some of the biggest mysteries of solar physics. This means that researchers can begin building sensors for ‘in situ’ measurements of the solar system's innermost frontier. Lika Guhathakurta, NASA Solar Probe Programme scientist said: "For the first time, we'll be able to 'touch, taste and smell' the sun." Last year, NASA invited top researchers around the world to submit proposals detailing possible science investigations for the pioneering spacecraft. More details at: NASA Science News
About Sunspot Cycles
Dark spots appear at places on the Sun where its magnetic field is concentrated. The number of sunspots is controlled by the amount of distortion of the Sun's magnetic field. The magnetic field becomes distorted because the Sun's equator and core rotate more quickly than its other parts. As a result, sunspot activity varies over an average 11-year cycle. During this period, the Sun goes from a solar minimum (fewer spots) to a solar maximum (more spots) and back to a minimum again. The solar magnetic activity cycle is the main source of the ~10.7 year periodic solar variation, which drives variations in space weather and to some degree weather on the ground and possibly climate change. (BBC article via Ken Fletcher)
Thanks to Ken Fletcher and Mike Terry for regular updates.
Wednesday, 18 August 2010
September 2010
Propagation Summary
August has been an interesting month with a massive M1 Solar Flare on August 7th which narrowly missed earth and resulted in the Northern Lights being visible as far south as Iowa, USA. A Persuid meteor shower also passed the Earth over a few days around 12th August which was actually visible to the naked eye in some parts of the world, which should have produced some interesting results for Radio Amateurs. (The next Persuid Meteor shower is forecast for 5-17 September, peaking on the 9th. http://www.imo.net/calendar/2010#julsep )
The NOAA report that On Saturday, August 14, 2010 a small solar flare erupted on the Sun at about 6am EDT. Associated with this flare was a coronal mass ejection (CME) that was partially directed towards the Earth. Also associated with this event was a S1 or minor solar radiation storm on the NOAA Space Weather Scales. The only impacts expected for a solar radiation storm of this magnitude are minor impacts to HF radio communications in the polar regions. However, this is the first solar radiation storm of Solar Cycle 24 and the first solar radiation storm since December of 2006. http://www.swpc.noaa.gov/ .
However, the sunspot number progression chart at Solarcycle24.com still shows sunspot activity to be actually lower than predicted. ( http://solarcycle24.com/sunspots.htm ) Apart from a noticeable disturbance around the 23rd, August should end with relatively steady conditions with the Boulder A index at 5 and the K index at 2, and is forecast to remain the same until mid September. The Solar Flux is forecast to return to a steady 85 during this period. WM7D.net
Solar Cycle 25
Peaking around 2022, Solar Cycle 25 could be one of the weakest in centuries.
The Sun's Great Conveyor Belt has slowed to a record-low crawl, according to research by NASA solar physicist David Hathaway. "It's off the bottom of the charts," he says. "This has important repercussions for future solar activity." http://www.physorg.com/news66581392.html
Radio Fadeouts and Solar Flares
Solar flares produce copious amounts of electromagnetic radiation, the X-ray component of which increases the ionisation of the ionospheric D layer. HF communication generally depends on the reflection of signals from the higher F layer and such signals must travel through the D layer at least twice. Increased ionisation results in greater absorption of the signal in the D layer.
This effect is known as a short-wave fadeout (SWF) and is observed as an increased attenuation of HF signals particularly at the lower frequencies. The fadeout follows closely the pattern of the solar flare, being observed at the same time as the flare. Fadeouts mostly have a rapid onset of a few minutes and a slower decline lasting perhaps an hour (this is highly variable).
A property of SWFs is that they affect the lower HF frequencies more than the higher ones which may not be affected at all. The high frequencies are the last to be affected and the first to recover.
An important feature of SWFs is that the HF circuit is affected only if there is an ionospheric reflection point for the signal in the sunlit hemisphere. No effect is observed if all the reflection points are located in the night hemisphere which is shadowed from the X-rays from the flare.
The intensity of flares at X-ray wavelengths allows us to estimate the extent (both geographical and in frequency) of a fadeout. This intensity is now measured by satellite and so IPS has established a page on the Internet to show the extent of fadeouts in near real-time at:
http://www.ips.gov.au/HF_Systems/6/2/1
Links to these articles and more can be found at www.jameswelsh.org.uk
August has been an interesting month with a massive M1 Solar Flare on August 7th which narrowly missed earth and resulted in the Northern Lights being visible as far south as Iowa, USA. A Persuid meteor shower also passed the Earth over a few days around 12th August which was actually visible to the naked eye in some parts of the world, which should have produced some interesting results for Radio Amateurs. (The next Persuid Meteor shower is forecast for 5-17 September, peaking on the 9th. http://www.imo.net/calendar/2010#julsep )
The NOAA report that On Saturday, August 14, 2010 a small solar flare erupted on the Sun at about 6am EDT. Associated with this flare was a coronal mass ejection (CME) that was partially directed towards the Earth. Also associated with this event was a S1 or minor solar radiation storm on the NOAA Space Weather Scales. The only impacts expected for a solar radiation storm of this magnitude are minor impacts to HF radio communications in the polar regions. However, this is the first solar radiation storm of Solar Cycle 24 and the first solar radiation storm since December of 2006. http://www.swpc.noaa.gov/ .
However, the sunspot number progression chart at Solarcycle24.com still shows sunspot activity to be actually lower than predicted. ( http://solarcycle24.com/sunspots.htm ) Apart from a noticeable disturbance around the 23rd, August should end with relatively steady conditions with the Boulder A index at 5 and the K index at 2, and is forecast to remain the same until mid September. The Solar Flux is forecast to return to a steady 85 during this period. WM7D.net
Solar Cycle 25
Peaking around 2022, Solar Cycle 25 could be one of the weakest in centuries.
The Sun's Great Conveyor Belt has slowed to a record-low crawl, according to research by NASA solar physicist David Hathaway. "It's off the bottom of the charts," he says. "This has important repercussions for future solar activity." http://www.physorg.com/news66581392.html
Radio Fadeouts and Solar Flares
Solar flares produce copious amounts of electromagnetic radiation, the X-ray component of which increases the ionisation of the ionospheric D layer. HF communication generally depends on the reflection of signals from the higher F layer and such signals must travel through the D layer at least twice. Increased ionisation results in greater absorption of the signal in the D layer.
This effect is known as a short-wave fadeout (SWF) and is observed as an increased attenuation of HF signals particularly at the lower frequencies. The fadeout follows closely the pattern of the solar flare, being observed at the same time as the flare. Fadeouts mostly have a rapid onset of a few minutes and a slower decline lasting perhaps an hour (this is highly variable).
A property of SWFs is that they affect the lower HF frequencies more than the higher ones which may not be affected at all. The high frequencies are the last to be affected and the first to recover.
An important feature of SWFs is that the HF circuit is affected only if there is an ionospheric reflection point for the signal in the sunlit hemisphere. No effect is observed if all the reflection points are located in the night hemisphere which is shadowed from the X-rays from the flare.
The intensity of flares at X-ray wavelengths allows us to estimate the extent (both geographical and in frequency) of a fadeout. This intensity is now measured by satellite and so IPS has established a page on the Internet to show the extent of fadeouts in near real-time at:
http://www.ips.gov.au/HF_Systems/6/2/1
Links to these articles and more can be found at www.jameswelsh.org.uk
Saturday, 24 July 2010
August 2010
Propagation Summary
Conditions have remained the same during July, apart from the slight disturbance between the 23rd and the 28th (Sunspot Number 1084) during which the Boulder A index will have gone as high as 15 and the K index wil have hit 5. The Solar Flux will have dropped to 72 by 1st August, returning to it’s the recent ‘norm’ of 80 by the August 6th. ( From: http://www.wm7d.net/hamradio/solar/27d_forecast.shtml )
Sunspot numbers are still around 50% below the targets forecast by Solarcycle24.com (http://solarcycle24.com/sunspots.htm ) See also Steve Nichols’ UK Short Path Propagation Forecast at: http://www.infotechcomms.net/propcharts/
Steve Nichol (GOKYA) ‘s Propagation Forecast
“Some people have suggested that the bands are improving, but I think they are confusing Sporadic E (Es) openings with F layer. This seasonal effect is opening up 20-10m and even 6m and 2m with good, strong openings up to 1,300 miles.
Multi-hop Es is stretching this even further, but we are not seeing an improvement in F layer propagation and Es will be less prevalent as the summer wears on.
Mid-to-late September will be the acid test – and with flux levels in the 70s we are not going to see many trans-Atlantic openings on 10m. Sorry!
20m (14MHz) is likely to be the best DX band between sunrise and sunset, although the band will be noisier than the winter period and not as reliable for long-haul contacts. The higher MUFs at night mean that 20m may remain open during the evening to DX. Short skip may also be possible due to summer sporadic-E.” http://www.g0kya.blogspot.com/
All About Sporadic E
“Sporadic E is irregular scattered patches of relatively dense ionization that develop seasonally within the E region and that reflect and scatter radio frequencies up to 150 MHz. Sporadic E is a regular daytime occurrence over the equatorial regions and is common in the temperate latitudes in late spring ,early summer and, to a lesser degree, in early winter. At high, i.e., polar, latitudes, Sporadic E can accompany Auroras and associated disturbed magnetic conditions. It can sometimes support reflections for distances up to 2,400 km.
Sporadic E is a form of propagation that can arise with little warning, and enable radio frequencies of 150 MHz and more to travel over distances of a thousand kilometres and more. Many people will have experienced it in the days of the old VHF TV transmissions.
When sporadic E propagation arose, it would result in severe interference to the signals. Even now VHF FM broadcasts in the 88 - 108 MHz band can be affected. In many instances the arrival of Sporadic E can cause unwanted interference as signals that are normally too distant to be heard appear. possible.
Sporadic E arises when clouds of intense ionisation form in the region of the E layer. These clouds can have very high levels of ionisation, allowing frequencies up to about 150 MHz to be reflected on some occasions. The clouds are usually comparatively small, measuring only about 50 to 150 kilometres in diameter. Their shape is irregular. Sometimes they may be almost circular, whereas others may be long and thin. They are also surprisingly thin, often only measuring a few hundred metres in depth.
These clouds appear almost at random, although there are times when they are more likely to occur. They form in the day, and dissipate within a few hours. You can read the complete article at:
http://www.g4xgt.co.uk/what-is-sporadic-e.htm
There are also some extra Sporadic E related links and more at: www.jameswelsh.org.uk
Conditions have remained the same during July, apart from the slight disturbance between the 23rd and the 28th (Sunspot Number 1084) during which the Boulder A index will have gone as high as 15 and the K index wil have hit 5. The Solar Flux will have dropped to 72 by 1st August, returning to it’s the recent ‘norm’ of 80 by the August 6th. ( From: http://www.wm7d.net/hamradio/solar/27d_forecast.shtml )
Sunspot numbers are still around 50% below the targets forecast by Solarcycle24.com (http://solarcycle24.com/sunspots.htm ) See also Steve Nichols’ UK Short Path Propagation Forecast at: http://www.infotechcomms.net/propcharts/
Steve Nichol (GOKYA) ‘s Propagation Forecast
“Some people have suggested that the bands are improving, but I think they are confusing Sporadic E (Es) openings with F layer. This seasonal effect is opening up 20-10m and even 6m and 2m with good, strong openings up to 1,300 miles.
Multi-hop Es is stretching this even further, but we are not seeing an improvement in F layer propagation and Es will be less prevalent as the summer wears on.
Mid-to-late September will be the acid test – and with flux levels in the 70s we are not going to see many trans-Atlantic openings on 10m. Sorry!
20m (14MHz) is likely to be the best DX band between sunrise and sunset, although the band will be noisier than the winter period and not as reliable for long-haul contacts. The higher MUFs at night mean that 20m may remain open during the evening to DX. Short skip may also be possible due to summer sporadic-E.” http://www.g0kya.blogspot.com/
All About Sporadic E
“Sporadic E is irregular scattered patches of relatively dense ionization that develop seasonally within the E region and that reflect and scatter radio frequencies up to 150 MHz. Sporadic E is a regular daytime occurrence over the equatorial regions and is common in the temperate latitudes in late spring ,early summer and, to a lesser degree, in early winter. At high, i.e., polar, latitudes, Sporadic E can accompany Auroras and associated disturbed magnetic conditions. It can sometimes support reflections for distances up to 2,400 km.
Sporadic E is a form of propagation that can arise with little warning, and enable radio frequencies of 150 MHz and more to travel over distances of a thousand kilometres and more. Many people will have experienced it in the days of the old VHF TV transmissions.
When sporadic E propagation arose, it would result in severe interference to the signals. Even now VHF FM broadcasts in the 88 - 108 MHz band can be affected. In many instances the arrival of Sporadic E can cause unwanted interference as signals that are normally too distant to be heard appear. possible.
Sporadic E arises when clouds of intense ionisation form in the region of the E layer. These clouds can have very high levels of ionisation, allowing frequencies up to about 150 MHz to be reflected on some occasions. The clouds are usually comparatively small, measuring only about 50 to 150 kilometres in diameter. Their shape is irregular. Sometimes they may be almost circular, whereas others may be long and thin. They are also surprisingly thin, often only measuring a few hundred metres in depth.
These clouds appear almost at random, although there are times when they are more likely to occur. They form in the day, and dissipate within a few hours. You can read the complete article at:
http://www.g4xgt.co.uk/what-is-sporadic-e.htm
There are also some extra Sporadic E related links and more at: www.jameswelsh.org.uk
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