Propagation Forecast
The last week in October will have been quiet with the 'A' index at 5 and the ‘K’ at 2, but there will be a disturbance peaking on the 30th with the ‘A’ index at 15 and the ‘K’ at 4. The next major disturbance will peak on November 7th with the 'A' index again at 15 and the ‘K’ at 4. This should settle back to normal by the 10th. The Solar Flux however should remain at 68, rising to 70 by the 4th November then dropping to 69 by the 13th. (www.wm7d.net)
“New Cycle” Sunspot
On 19th October, a "new-cycle" sunspot belonging to Solar Cycle 24 was emerging near the sun's north-eastern limb. This was the third time in as many weeks that a new-cycle sunspot has interrupted the year's remarkable run of blank suns.
The accelerating pace of new-cycle sunspot production is an encouraging sign that, while solar activity remains very low, the sunspot cycle is unfolding more or less normally. We are not stuck in a permanent solar minimum.
IRTS Radio News Bulletin 19 October 2008 http://www.irts.ie
Space Weather reports that for the first time in months, a significant sunspot is emerging on the solar disk. Its described as a fast-growing active region with two dark cores, each larger than Earth. The magnetic polarity of the sunspot identifies it as a member of new Sunspot Cycle 24. This is viewed as an encouraging sign that the 11-year solar cycle is indeed progressing, albeit very, very slowly. (www.spaceweather.com)
2008, Blankest Year of the Space Age
Astronomers who count sunspots have announced that 2008 is now the "blankest year" of the Space Age. As of Sept. 27, 2008, the sun had been blank, i.e., had no visible sunspots, on 200 days of the year. To find a year with more blank suns, you have to go back to 1954, three years before the launch of Sputnik, when the sun was blank 241 times.
"Sunspot counts are at a 50-year low," says solar physicist David Hathaway of the NASA Marshall Space Flight Center. "We're experiencing a deep minimum of the solar cycle."
If solar activity continues as low as it has been, 2008 could rack up a whopping 290 spotless days by the end of December, making it a century-level year in terms of spotlessness.
Hathaway cautions that this development may sound more exciting than it actually is: "While the solar minimum of 2008 is shaping up to be the deepest of the Space Age, it is still unremarkable compared to the long and deep solar minima of the late 19th and early 20th centuries." Those earlier minima routinely racked up 200 to 300 spotless days per year. (NASA Science News September 30, 2008)
http://science.nasa.gov/headlines/y2008/30sep_blankyear.htm?list1066509
Jim Linton VK3PC of Wireless Institute Of Australia reports: “The false start announced last year for the new Solar Cycle 24 has been followed up with speculation of things like `double dip' minima and even a new ice age for sunspots. But let's try to stay positive and not subscribe to thoughts of another minimum of 70 years, as occurred from 1645 to 1715, the only flat-lining in sunspot cycles since records.
Looking back at the onset of previous cycles that followed prolonged periods without sunspots, gives indication that Cycle 24 may have a much greater start-up intensity. Should it behave like Cycles 11 to 14 in the 19th century there will be more years rising and a shorter period in decline. The latest prediction is that Cycle 24 will be begin in mid 2009.
The prolonged solar minimum is also occurring at a time of reports in the northern hemisphere of continued sporadic-E enhancement on both the ten and six metre bands.”
Jim Linton, VK3PC. Amatuer Radio Newsline (Wireless Institute Of Australia http://www.wia.org.au/)
Thanks to Mike Terry and Ken Fletcher for regular updates.
Links to these articles and more can be found on my links page: www.jameswelsh.org.uk
Friday, 24 October 2008
Thursday, 18 September 2008
October 2008
Propagation Forecast.
The ‘mill pond’ conditions are likely to continue until the end of September, with the A index at 5 and the K index at 2 which I will refer to as ‘normal’ for this period. October will begin with a disturbance peaking on October 1st with the A Index rising to 30 and the K index to 5. This will have calmed down to ‘normal’ by October 8th and will be followed by a lesser disturbance on 12th October with the A index at 12 and the K Index at at 14, returning to ‘normal’ by the 15th. The Solar flux, however will remain at a constant 67 during this period. From: http://www.wm7d.net/hamradio/solar/27d_forecast.shtml
There is still much speculation among the scientific community about the true beginning of Solar Cycle 24. In 2008, a negatively charged sunspot on January 24 was thought to be the start of the new solar cycle, as was another very weak sunspot on 31 July. The general consensus of opinion is now mid 2009!
Solar cycle 24 “will begin in mid 2009”
The false start announced last year for the new Solar Cycle 24 has been followed up with speculation of things like ‘double dip’ minima and even a new ice age for sunspots. But let’s try to stay positive and not subscribe to thoughts of another minimum of 70 years, as occurred from 1645 to 1715, the only flat-lining in sunspot cycles since records.
Looking back at the onset of previous cycles that followed prolonged periods without Sunspots, gives indication that Cycle 24 may have a much greater start-up intensity. Should it behave like Cycles 11 to 14 in the 19th century there will be more years rising and a shorter period in decline.
The latest prediction is that Cycle 24 will begin in mid 2009. The prolonged solar minimum is also occurring at a time of reports in the Northern Hemisphere of continued sporadic-E enhancement on both the ten and six metre bands.
Greyline propagation on HF also is experiencing a lack of geomagnetic disturbance, which is a good thing. Jim Linton VK3PC. Wireless Institute of Australia http://www.wia.org.au/
A new sunspot, number 1001, emerged on Thursday, September 11. It is actually a single group with two small magnetic disturbances. The previous Sunspot, was a weak one barely emerging on August 21-22. It was so small that some observatories didn't count it, but it was a Cycle 24 spot.
August was much ballyhooed as the first time since 1913 that there was a month or more between the most recent sunspot appearances. Actually it was the first time that a whole calendar month went by with no spots. Of course, this doesn't really mean anything more than any other 30 day period with no spots, because the calendar is based on arbitrary beginnings and endings.
From K7RA via Southgate ARC http://www.southgatearc.org/rss/
See also this article about solar cycle 24 and its implications for the United States by David Archibald at: www.warwickhughes.com/agri/Solar_Arch_NY_Mar2_08.pdf
I also found this article from Ben Carlson writing in The Atlantic magazine:
Will changes in sunspot activity wreak havoc on earth? With the advent of Solar Cycle 24, many scientists expect a massive spike in solar activity that will have the potential to disrupt satellites, cell phones, and air traffic in 2012. But the real concern is Solar Cycle 25. Around 2022, a catastrophic drop in sun activity—the lowest in centuries, according to NASA—may cause temperatures on earth to plunge, inaugurating an extended period of cold. In other words, a new Ice Age.
What seems to have escaped many reporters’ grasps is that this dire scenario doesn’t square with the facts. The only evidence its proponents present is the seeming correlation between the “Little Ice Age” of the 17th and 18th centuries and a concurrent period of solar slump. But as everyone would do well to remember, climate is far more complicated than that. As one of the most chaotic and multi-variable systems humans study, it is easy to see why debates over climate change often occur.
Ben Carlson The Atlantic http://thecurrent.theatlantic.com/archives/2008/02/the-ice-age-cometh.phpThanks to Ken Fletcher and Mike Terry for regular updates.
Links to these articles and more can be found at: www.jameswelsh.org.uk
The ‘mill pond’ conditions are likely to continue until the end of September, with the A index at 5 and the K index at 2 which I will refer to as ‘normal’ for this period. October will begin with a disturbance peaking on October 1st with the A Index rising to 30 and the K index to 5. This will have calmed down to ‘normal’ by October 8th and will be followed by a lesser disturbance on 12th October with the A index at 12 and the K Index at at 14, returning to ‘normal’ by the 15th. The Solar flux, however will remain at a constant 67 during this period. From: http://www.wm7d.net/hamradio/solar/27d_forecast.shtml
There is still much speculation among the scientific community about the true beginning of Solar Cycle 24. In 2008, a negatively charged sunspot on January 24 was thought to be the start of the new solar cycle, as was another very weak sunspot on 31 July. The general consensus of opinion is now mid 2009!
Solar cycle 24 “will begin in mid 2009”
The false start announced last year for the new Solar Cycle 24 has been followed up with speculation of things like ‘double dip’ minima and even a new ice age for sunspots. But let’s try to stay positive and not subscribe to thoughts of another minimum of 70 years, as occurred from 1645 to 1715, the only flat-lining in sunspot cycles since records.
Looking back at the onset of previous cycles that followed prolonged periods without Sunspots, gives indication that Cycle 24 may have a much greater start-up intensity. Should it behave like Cycles 11 to 14 in the 19th century there will be more years rising and a shorter period in decline.
The latest prediction is that Cycle 24 will begin in mid 2009. The prolonged solar minimum is also occurring at a time of reports in the Northern Hemisphere of continued sporadic-E enhancement on both the ten and six metre bands.
Greyline propagation on HF also is experiencing a lack of geomagnetic disturbance, which is a good thing. Jim Linton VK3PC. Wireless Institute of Australia http://www.wia.org.au/
A new sunspot, number 1001, emerged on Thursday, September 11. It is actually a single group with two small magnetic disturbances. The previous Sunspot, was a weak one barely emerging on August 21-22. It was so small that some observatories didn't count it, but it was a Cycle 24 spot.
August was much ballyhooed as the first time since 1913 that there was a month or more between the most recent sunspot appearances. Actually it was the first time that a whole calendar month went by with no spots. Of course, this doesn't really mean anything more than any other 30 day period with no spots, because the calendar is based on arbitrary beginnings and endings.
From K7RA via Southgate ARC http://www.southgatearc.org/rss/
See also this article about solar cycle 24 and its implications for the United States by David Archibald at: www.warwickhughes.com/agri/Solar_Arch_NY_Mar2_08.pdf
I also found this article from Ben Carlson writing in The Atlantic magazine:
Will changes in sunspot activity wreak havoc on earth? With the advent of Solar Cycle 24, many scientists expect a massive spike in solar activity that will have the potential to disrupt satellites, cell phones, and air traffic in 2012. But the real concern is Solar Cycle 25. Around 2022, a catastrophic drop in sun activity—the lowest in centuries, according to NASA—may cause temperatures on earth to plunge, inaugurating an extended period of cold. In other words, a new Ice Age.
What seems to have escaped many reporters’ grasps is that this dire scenario doesn’t square with the facts. The only evidence its proponents present is the seeming correlation between the “Little Ice Age” of the 17th and 18th centuries and a concurrent period of solar slump. But as everyone would do well to remember, climate is far more complicated than that. As one of the most chaotic and multi-variable systems humans study, it is easy to see why debates over climate change often occur.
Ben Carlson The Atlantic http://thecurrent.theatlantic.com/archives/2008/02/the-ice-age-cometh.phpThanks to Ken Fletcher and Mike Terry for regular updates.
Links to these articles and more can be found at: www.jameswelsh.org.uk
Saturday, 23 August 2008
September 08
Propagation Forecast
From August 20th, conditions have remained quiet with the A index at 5, and the K index at 2. This is likely to remain the same except for September 5th with the A index at 18 and the K at 4. Also on September 12th, conditions should again become disturbed with the A index peaking at 20 on the 14th and the K index peaking at 5.
The Solar Flux, however has remained at a steady 66 and is likely to remain the same until at least mid September
MUF Map A near-real-time Maximum Usable Frequency map can be found at: http://www.spacew.com/www/realtime.php
Sunspot Numbers For 2008. With the exception of March, monthly average sunspot numbers have been on a downward trend so far during 2008. January started with an average sunspot number of 26 slowly dropping to 12 by the end of July. NOAA Predicted trends for 2008 have been fairly accurate, although sunspot numbers have been generally higher than predicted. Details at: http://www.solarcycle24.com/sunspot.htm
HF Propagation Flash Movie
Here is a website featuring a flash movie which explains how HF radio propagation actually works: http://www.ae4rv.com/tn/propflash.htm .
A 45 day Solar Flux and A index forecast can also be found at: http://www.dxing.info/propagation
The Sun's Magnetic Field
When the transition from Cycle 23 to 24 occurs the magnetic field which surrounds the sun will change it's polarity. This will be apparent in the magnetic stucture of individual sunspot groups as seen in solar magnetograms such as those recorded at the IPS/USAF Learmonth Solar Observatory in Western Australia. With a change in the solar cycle, the polarity of the leader and trailer spots of a sunspot group are reversed. This observation, in conjunction with the latitude at which the new spot formed, will indicate that the change to the new solar cycle is underway. From: http://www.ips.gov.au/Educational
From August 20th, conditions have remained quiet with the A index at 5, and the K index at 2. This is likely to remain the same except for September 5th with the A index at 18 and the K at 4. Also on September 12th, conditions should again become disturbed with the A index peaking at 20 on the 14th and the K index peaking at 5.
The Solar Flux, however has remained at a steady 66 and is likely to remain the same until at least mid September
MUF Map A near-real-time Maximum Usable Frequency map can be found at: http://www.spacew.com/www/realtime.php
Sunspot Numbers For 2008. With the exception of March, monthly average sunspot numbers have been on a downward trend so far during 2008. January started with an average sunspot number of 26 slowly dropping to 12 by the end of July. NOAA Predicted trends for 2008 have been fairly accurate, although sunspot numbers have been generally higher than predicted. Details at: http://www.solarcycle24.com/sunspot.htm
HF Propagation Flash Movie
Here is a website featuring a flash movie which explains how HF radio propagation actually works: http://www.ae4rv.com/tn/propflash.htm .
A 45 day Solar Flux and A index forecast can also be found at: http://www.dxing.info/propagation
The Sun's Magnetic Field
When the transition from Cycle 23 to 24 occurs the magnetic field which surrounds the sun will change it's polarity. This will be apparent in the magnetic stucture of individual sunspot groups as seen in solar magnetograms such as those recorded at the IPS/USAF Learmonth Solar Observatory in Western Australia. With a change in the solar cycle, the polarity of the leader and trailer spots of a sunspot group are reversed. This observation, in conjunction with the latitude at which the new spot formed, will indicate that the change to the new solar cycle is underway. From: http://www.ips.gov.au/Educational
Saturday, 26 July 2008
August 08
Propagation Forecast
Propagation conditions during July have been fairly calm, especially from the 25th with the A index at 5 and the K index at 2. After a slight fluctuation on the 1st August, conditions will remain the same until the 7th when there will be another disturbance which will last until the 14th and will peak on the 8th with the A index at 20 and the K index at 5. Things will then remain calm until the 10th August with the A index rising to 10 and the K index to 3. The worst days will be 7th to the 12th and also the 18th.
The solar flux however will remain at 2 during the first week in August, rising to 5 by the 8th and settling back to 3 by the 18th. (http://www.wm7d.net)
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is generally poor to fair. (www.dxlc.com)
Solar Cycle 24 Prediction
June 27, 2008 During the annual Space Weather Workshop held in Boulder, CO in May, 2008, the Solar Cycle 24 Prediction Panel released an update to the prediction for the next solar cycle. In short, the update is that the panel has not yet made any changes to the prediction issued in April, 2007. The panel predicted solar minimum to occur in March, 2008. The panel expects the solar cycle to reach a peak sunspot number of 140 in October, 2011 or a peak of 90 in August, 2012.
The 2008 Perseid Meteor Shower 12th August.
"Peaking on August 12th, it should be a good show. "The time to look is during the dark hours before dawn on Tuesday, August 12th," says Bill Cooke of NASA's Meteoroid Environment Office at the Marshall Space Flight Center. "There should be plenty of meteors--perhaps one or two every minute.
The source of the shower is Comet Swift-Tuttle. Although the comet is far away, currently located beyond the orbit of Uranus, a trail of debris from the comet stretches all the way back to Earth.
Crossing the trail in August, Earth will be pelted by specks of comet dust hitting the atmosphere at 132,000 mph. At that speed, even a flimsy speck of dust makes a vivid streak of light when it disintegrates--a meteor! Because, Swift-Tuttle's meteors streak out of the constellation Perseus, they are called "Perseids.
Serious meteor hunters will begin their watch early, on Monday evening, August 11th, around 9 pm when Perseus first rises in the northeast. This is the time to look for Perseid Earthgrazers--meteors that approach from the horizon and skim the atmosphere overhead like a stone skipping across the surface of a pond." (NASA Science News http://science.nasa.gov/headlines/ )
Thanks to Ken Fletcher and Mike Terry for regular updates. Links can be found on my web page.
Propagation conditions during July have been fairly calm, especially from the 25th with the A index at 5 and the K index at 2. After a slight fluctuation on the 1st August, conditions will remain the same until the 7th when there will be another disturbance which will last until the 14th and will peak on the 8th with the A index at 20 and the K index at 5. Things will then remain calm until the 10th August with the A index rising to 10 and the K index to 3. The worst days will be 7th to the 12th and also the 18th.
The solar flux however will remain at 2 during the first week in August, rising to 5 by the 8th and settling back to 3 by the 18th. (http://www.wm7d.net)
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is generally poor to fair. (www.dxlc.com)
Solar Cycle 24 Prediction
June 27, 2008 During the annual Space Weather Workshop held in Boulder, CO in May, 2008, the Solar Cycle 24 Prediction Panel released an update to the prediction for the next solar cycle. In short, the update is that the panel has not yet made any changes to the prediction issued in April, 2007. The panel predicted solar minimum to occur in March, 2008. The panel expects the solar cycle to reach a peak sunspot number of 140 in October, 2011 or a peak of 90 in August, 2012.
The 2008 Perseid Meteor Shower 12th August.
"Peaking on August 12th, it should be a good show. "The time to look is during the dark hours before dawn on Tuesday, August 12th," says Bill Cooke of NASA's Meteoroid Environment Office at the Marshall Space Flight Center. "There should be plenty of meteors--perhaps one or two every minute.
The source of the shower is Comet Swift-Tuttle. Although the comet is far away, currently located beyond the orbit of Uranus, a trail of debris from the comet stretches all the way back to Earth.
Crossing the trail in August, Earth will be pelted by specks of comet dust hitting the atmosphere at 132,000 mph. At that speed, even a flimsy speck of dust makes a vivid streak of light when it disintegrates--a meteor! Because, Swift-Tuttle's meteors streak out of the constellation Perseus, they are called "Perseids.
Serious meteor hunters will begin their watch early, on Monday evening, August 11th, around 9 pm when Perseus first rises in the northeast. This is the time to look for Perseid Earthgrazers--meteors that approach from the horizon and skim the atmosphere overhead like a stone skipping across the surface of a pond." (NASA Science News http://science.nasa.gov/headlines/ )
Thanks to Ken Fletcher and Mike Terry for regular updates. Links can be found on my web page.
Thursday, 19 June 2008
July 2008
Propagation Forecast
The second half of June will have seen 2 minor disturbances. On the 19th and 20th. The A index was at 10 and the K at 3, returning to ‘normal’ by the 21st with the A index at 5 and the K index at 2, until the 25th to the 27th with the A index peaking at 10 on the 26th. ‘Normal ‘ conditions will prevail until July 3rd to the 5th, with the A index again peaking at 10 on the 4th July. Things will remain ‘normal until 11th July with another disturbance until at least the 14th, the worst day being the 12th, with the A index peaking at 15 and the K index at 4.
Sunspots and Global Warming
The Spórer minimum (1420-1570) The Maunder minimum (1745-1615), and the Dalton Minimum (1790 to 1830) have coincided with a time when Earth’s climate was colder than average. The correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.
Like the subsequent Maunder Minimum, the Spörer Minimum coincided with a time when Earth's climate was colder than average. This correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.
Here is an interesting article in the Belfast Telegraph by Dr David Whitehouse (12 May 2007):
Can the Sun Save Us from Global Warming? (Low Sunspot Activity)
"Something is happening to our Sun. It has to do with sunspots, or rather the activity cycle their coming and going signifies. After a period of exceptionally high activity in the 20th century, our Sun has suddenly gone exceptionally quiet. Months have passed with no spots visible on its disc.
We are at the end of one cycle of activity and astronomers are waiting for the sunspots to return and mark the start of the next, the so-called cycle 24. They have been waiting for a while now with no sign it's on its way any time soon.
Sunspots – dark magnetic blotches on the Sun's surface – come and go in a roughly 11-year cycle of activity first noticed in 1843. It's related to the motion of super-hot, electrically charged gas inside the Sun – a kind of internal conveyor belt where vast sub-surface rivers of gas take 40 years to circulate from the equator to the poles and back. Somehow, in a way not very well understood, this circulation produces the sunspot cycle in which every 11 years there is a sunspot maximum followed by a minimum. But recently the Sun's internal circulation has been failing. In May 2006 this conveyor belt had slowed to a crawl – a record low. Nasa scientist David Hathaway said: "It's off the bottom of the charts... this has important repercussions for future solar activity." What's more, it's not the only indicator that the Sun is up to something.
Astronomers called it the "Maunder Minimum." It was an astonishing discovery: our Sun can change. Between 1645 and 1715 sunspots were rare. About 50 were observed; there should have been 50,000.
Ever since the sunspot cycle was discovered, researchers have looked for its rhythm superimposed on the Earth's climate. In some cases it's there but usually at low levels. But there was something strange about the time when the sunspots disappeared that left scientists to ponder if the sun's unusual behaviour could have something to do with the fact that the 17th century was also a time when the Earth's northern hemisphere chilled with devastating consequences."
THE SUN'S CHILLY IMPACT ON EARTH
A new NASA computer climate model reinforces the long-standing theory that low solar activity could have changed the atmospheric circulation in the Northern Hemisphere from the 1400s to the 1700s and triggered a "Little Ice Age" in several regions including North America and Europe. Changes in the sun's energy was one of the biggest factors influencing climate change during this period, but have since been superceded by greenhouse gases due to the industrial revolution. (NASA News).
(Thanks to Ken Fletcher and Mike Terry for regular updates). Links to the full articles are on my website. http://www.jameswelsh.org.uk
The second half of June will have seen 2 minor disturbances. On the 19th and 20th. The A index was at 10 and the K at 3, returning to ‘normal’ by the 21st with the A index at 5 and the K index at 2, until the 25th to the 27th with the A index peaking at 10 on the 26th. ‘Normal ‘ conditions will prevail until July 3rd to the 5th, with the A index again peaking at 10 on the 4th July. Things will remain ‘normal until 11th July with another disturbance until at least the 14th, the worst day being the 12th, with the A index peaking at 15 and the K index at 4.
Sunspots and Global Warming
The Spórer minimum (1420-1570) The Maunder minimum (1745-1615), and the Dalton Minimum (1790 to 1830) have coincided with a time when Earth’s climate was colder than average. The correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.
Like the subsequent Maunder Minimum, the Spörer Minimum coincided with a time when Earth's climate was colder than average. This correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.
Here is an interesting article in the Belfast Telegraph by Dr David Whitehouse (12 May 2007):
Can the Sun Save Us from Global Warming? (Low Sunspot Activity)
"Something is happening to our Sun. It has to do with sunspots, or rather the activity cycle their coming and going signifies. After a period of exceptionally high activity in the 20th century, our Sun has suddenly gone exceptionally quiet. Months have passed with no spots visible on its disc.
We are at the end of one cycle of activity and astronomers are waiting for the sunspots to return and mark the start of the next, the so-called cycle 24. They have been waiting for a while now with no sign it's on its way any time soon.
Sunspots – dark magnetic blotches on the Sun's surface – come and go in a roughly 11-year cycle of activity first noticed in 1843. It's related to the motion of super-hot, electrically charged gas inside the Sun – a kind of internal conveyor belt where vast sub-surface rivers of gas take 40 years to circulate from the equator to the poles and back. Somehow, in a way not very well understood, this circulation produces the sunspot cycle in which every 11 years there is a sunspot maximum followed by a minimum. But recently the Sun's internal circulation has been failing. In May 2006 this conveyor belt had slowed to a crawl – a record low. Nasa scientist David Hathaway said: "It's off the bottom of the charts... this has important repercussions for future solar activity." What's more, it's not the only indicator that the Sun is up to something.
Astronomers called it the "Maunder Minimum." It was an astonishing discovery: our Sun can change. Between 1645 and 1715 sunspots were rare. About 50 were observed; there should have been 50,000.
Ever since the sunspot cycle was discovered, researchers have looked for its rhythm superimposed on the Earth's climate. In some cases it's there but usually at low levels. But there was something strange about the time when the sunspots disappeared that left scientists to ponder if the sun's unusual behaviour could have something to do with the fact that the 17th century was also a time when the Earth's northern hemisphere chilled with devastating consequences."
THE SUN'S CHILLY IMPACT ON EARTH
A new NASA computer climate model reinforces the long-standing theory that low solar activity could have changed the atmospheric circulation in the Northern Hemisphere from the 1400s to the 1700s and triggered a "Little Ice Age" in several regions including North America and Europe. Changes in the sun's energy was one of the biggest factors influencing climate change during this period, but have since been superceded by greenhouse gases due to the industrial revolution. (NASA News).
(Thanks to Ken Fletcher and Mike Terry for regular updates). Links to the full articles are on my website. http://www.jameswelsh.org.uk
Thursday, 22 May 2008
June 2008
Propagation Summary
A recurrent coronal hole (CH327) was in an Earth facing position on May 18-19. Another recurrent coronal hole (CH328) rotated into an Earth facing position on May 23-25.
Following a disturbance around 21st May, with the A index at 25, and the K at 5, conditions will have settled down by 23rd May, with the A index at 10 and the K at 3 where it will remain until May 31st with the A rising to 10 and the K index remaining at 3 until 3rd June when the A will drop to 5 and the K to 2.
The Solar Flux, however will drop from 72 to 68 by 25th May until 9th June when it will rise to 70. This is then followed by another rise to 72 by the 12th where it will remain until at least the 16th.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.
(From WWM7D.com, NOAA and www.dxlc.com/solar).
The Ionosphere
Scientists call the ionosphere an extension or a part of the thermosphere. So technically, the ionosphere is not another atmospheric layer, but a region of the atmosphere. The ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere. Even so, it is extremely important!
The upper atmosphere is ionized by solar radiation. Under normal conditions free electrons and ions tend to recombine and a balance is established between electron and ion production and loss.
Ionization processes release energy, which heat up the upper atmosphere. So temperature increases with height in the ionosphere region to the extent that by 150-200km, the Earth's atmosphere is extremely hot compared to surface temperatures.
Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras and the mega-ampere currents that heat the atmosphere at high latitudes during geomagnetically active times. During storms, depletions and enhancements of ionization occur depending on the local time and geographical location.
Aeronomy is a term of recent origin, which is applied to the processes, both physical and chemical, of the ionosphere. From http://www.windows.ucar.edu/ (University Of Michigan)
HF Propagation Predictions For 2008
Here is an interesting website by G4FKH, which has a monthly chart of predicted HF conditions listed by capital cities: http://uk.geocities.com/g4fkh@btinternet.com/
See also: http://www.hfradio.org/propagation.html
The New Shortwave Propagation Handbook (Paperback) - by George Jacobs, Theodore J. Cohen, R. B. Rose. The NEW Shortwave Progagation Handbook may well be the only book you'll need on the subject of ionospheric propagation! It is a "must read" for Radio Amateurs, Shortwave Listeners, and radio communicators of any type who need to make the most productive use of the radio spectrum, regardless of the time of day, the season of the year, or the state of the sunspot cycle. It will become your ever-present companion the operating table as you master the art of shortwave radio progagation. (Available from Amazon.com posted from the USA)
Thanks to KF and MET for regular updates.
A recurrent coronal hole (CH327) was in an Earth facing position on May 18-19. Another recurrent coronal hole (CH328) rotated into an Earth facing position on May 23-25.
Following a disturbance around 21st May, with the A index at 25, and the K at 5, conditions will have settled down by 23rd May, with the A index at 10 and the K at 3 where it will remain until May 31st with the A rising to 10 and the K index remaining at 3 until 3rd June when the A will drop to 5 and the K to 2.
The Solar Flux, however will drop from 72 to 68 by 25th May until 9th June when it will rise to 70. This is then followed by another rise to 72 by the 12th where it will remain until at least the 16th.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.
(From WWM7D.com, NOAA and www.dxlc.com/solar).
The Ionosphere
Scientists call the ionosphere an extension or a part of the thermosphere. So technically, the ionosphere is not another atmospheric layer, but a region of the atmosphere. The ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere. Even so, it is extremely important!
The upper atmosphere is ionized by solar radiation. Under normal conditions free electrons and ions tend to recombine and a balance is established between electron and ion production and loss.
Ionization processes release energy, which heat up the upper atmosphere. So temperature increases with height in the ionosphere region to the extent that by 150-200km, the Earth's atmosphere is extremely hot compared to surface temperatures.
Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras and the mega-ampere currents that heat the atmosphere at high latitudes during geomagnetically active times. During storms, depletions and enhancements of ionization occur depending on the local time and geographical location.
Aeronomy is a term of recent origin, which is applied to the processes, both physical and chemical, of the ionosphere. From http://www.windows.ucar.edu/ (University Of Michigan)
HF Propagation Predictions For 2008
Here is an interesting website by G4FKH, which has a monthly chart of predicted HF conditions listed by capital cities: http://uk.geocities.com/g4fkh@btinternet.com/
See also: http://www.hfradio.org/propagation.html
The New Shortwave Propagation Handbook (Paperback) - by George Jacobs, Theodore J. Cohen, R. B. Rose. The NEW Shortwave Progagation Handbook may well be the only book you'll need on the subject of ionospheric propagation! It is a "must read" for Radio Amateurs, Shortwave Listeners, and radio communicators of any type who need to make the most productive use of the radio spectrum, regardless of the time of day, the season of the year, or the state of the sunspot cycle. It will become your ever-present companion the operating table as you master the art of shortwave radio progagation. (Available from Amazon.com posted from the USA)
Thanks to KF and MET for regular updates.
Friday, 2 May 2008
Propagation Report May 2008
Propagation Forecast
The last week in April has been quite stable following a minor disturbance on the 23rd apparently caused by a coronal hole. Details at: http://www.dxlc.com/solar/
From 27th to the 30th, the index has remained at 5 and the K at 2. The first week in May will be quite disturbed. On the 2nd May, the A index will peak at 20 and the K at 5, then by the 8th May, conditions will settle with the A index at 5 and the K index at 2 until May19th when conditions are likely to deteriorate with the A index rising to 10 and the K index to 3. The solar flux has a downward trend remaining at 75 for the last week in April, then dropping to 70 by 2nd May where it will remain till the 19th May when it again rises to 75.
(Via wm7d.net)
Propagation explained:
The Ionosphere: A collection of ionized particles and electrons in the uppermost portion of the earth's atmosphere which is formed by the interaction of the solar wind with the very thin air particles that have escaped the earth's gravity. These ions are responsible for the reflection or bending of radio waves occurring between certain critical frequencies with these critical frequencies varying with the degree of ionization. As a result, radio waves having frequencies higher the lowest usable frequency (LUF) but lower than the maximum usable frequency (MUF) are propagated over large distances.
D-Layer:
The lowest part of the ionosphere, the D-layer appears at an altitude of 50-95km. This layer has a negative effect on radio waves because it only absorbs radio-energy, particularly those frequencies below 7MHz. It develops shortly after sunrise and disappears shortly after sunset. This layer reaches maximum ionization when the sun is at its highest point in the sky and this layer is also responsible the complete absorption of sky waves from the 80m and 160m amateur bands as well as the AM broadcast band during the daytime hours.
E-layer:
This part of the ionosphere is located just above the D-layer at an altitude of 90-150km. This layer can only reflect radio waves having frequencies less than 5MHz. It has a negative effect on frequencies above 5MHz due to the partial absorption of these higher frequency radio waves. The E-layer develops shortly after sunrise and it disappears a few hours after sunset. The maximum ionization of this layer is reached around midday and the ions in this layer are mainly O2+.
F-layer:
Highest part of the ionosphere. The F-layer appears a few hours after sunset, when the F1- and F2-layers merge. The F-layer is located between 250km and 500km in altitude. Even well into the night, this layer may reflect radio waves up to 20 MHZ, and occasionally even up to 25 MHZ. Ions in the lower part of the F-layer are mainly NO+ and are predominantly O+ in the upper part.
Thanks to Mike Terry and Ken Fletcher for regular updates.
The last week in April has been quite stable following a minor disturbance on the 23rd apparently caused by a coronal hole. Details at: http://www.dxlc.com/solar/
From 27th to the 30th, the index has remained at 5 and the K at 2. The first week in May will be quite disturbed. On the 2nd May, the A index will peak at 20 and the K at 5, then by the 8th May, conditions will settle with the A index at 5 and the K index at 2 until May19th when conditions are likely to deteriorate with the A index rising to 10 and the K index to 3. The solar flux has a downward trend remaining at 75 for the last week in April, then dropping to 70 by 2nd May where it will remain till the 19th May when it again rises to 75.
(Via wm7d.net)
Propagation explained:
The Ionosphere: A collection of ionized particles and electrons in the uppermost portion of the earth's atmosphere which is formed by the interaction of the solar wind with the very thin air particles that have escaped the earth's gravity. These ions are responsible for the reflection or bending of radio waves occurring between certain critical frequencies with these critical frequencies varying with the degree of ionization. As a result, radio waves having frequencies higher the lowest usable frequency (LUF) but lower than the maximum usable frequency (MUF) are propagated over large distances.
D-Layer:
The lowest part of the ionosphere, the D-layer appears at an altitude of 50-95km. This layer has a negative effect on radio waves because it only absorbs radio-energy, particularly those frequencies below 7MHz. It develops shortly after sunrise and disappears shortly after sunset. This layer reaches maximum ionization when the sun is at its highest point in the sky and this layer is also responsible the complete absorption of sky waves from the 80m and 160m amateur bands as well as the AM broadcast band during the daytime hours.
E-layer:
This part of the ionosphere is located just above the D-layer at an altitude of 90-150km. This layer can only reflect radio waves having frequencies less than 5MHz. It has a negative effect on frequencies above 5MHz due to the partial absorption of these higher frequency radio waves. The E-layer develops shortly after sunrise and it disappears a few hours after sunset. The maximum ionization of this layer is reached around midday and the ions in this layer are mainly O2+.
F-layer:
Highest part of the ionosphere. The F-layer appears a few hours after sunset, when the F1- and F2-layers merge. The F-layer is located between 250km and 500km in altitude. Even well into the night, this layer may reflect radio waves up to 20 MHZ, and occasionally even up to 25 MHZ. Ions in the lower part of the F-layer are mainly NO+ and are predominantly O+ in the upper part.
Thanks to Mike Terry and Ken Fletcher for regular updates.
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