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#1
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Solar Hole?
How does this affect HF radio propagation/reception? http://spaceweather.com/ Current Conditions Solar Wind speed: 646.2 km/s density: 2.8 protons/cm3 Earth is inside a solar wind stream flowing from the indicated coronal hole. Credit: SOHO Extreme UV telescope Daily Sun: 14 Mar '07 The sun is blank today--no sunspots. Credit: SOHO/MDI Interplanetary Mag. Field Btotal: 4.7 nT Bz: 2.5 nT north |
#2
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Solar Hole?
On 2007-03-14 20:06:00 -0400, Larry Dighera said:
How does this affect HF radio propagation/reception? http://spaceweather.com/ Current Conditions Solar Wind speed: 646.2 km/s density: 2.8 protons/cm3 Earth is inside a solar wind stream flowing from the indicated coronal hole. Credit: SOHO Extreme UV telescope Daily Sun: 14 Mar '07 The sun is blank today--no sunspots. Credit: SOHO/MDI Interplanetary Mag. Field Btotal: 4.7 nT Bz: 2.5 nT north Google CME or Coronal Mass Ejection and learn all about it. |
#3
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Solar Hole?
Johnny Borborigmi schreef:
Google CME or Coronal Mass Ejection and learn all about it. A coronal hole is something different from a CME. A CME is a solar flare, giant burst from the sun whike a coronal hole is a relatively cooler area of the sun (they appear dark in EIT images) that also have a higher release of particles then other area's from the sun. A CME generally has more impact on earth (if it was earth bound) then a CH, as more matter is released. Things are a bit oversimplified, but HTH -- JeroenK |
#4
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Solar Hole?
On Wed, 14 Mar 2007 20:58:00 -0400, Johnny Borborigmi
wrote in : On 2007-03-14 20:06:00 -0400, Larry Dighera said: How does this affect HF radio propagation/reception? http://spaceweather.com/ Current Conditions Solar Wind speed: 646.2 km/s density: 2.8 protons/cm3 Earth is inside a solar wind stream flowing from the indicated coronal hole. Credit: SOHO Extreme UV telescope Daily Sun: 14 Mar '07 The sun is blank today--no sunspots. Credit: SOHO/MDI Interplanetary Mag. Field Btotal: 4.7 nT Bz: 2.5 nT north Google CME or Coronal Mass Ejection and learn all about it. I always thought CMEs were associated with sunspots. There are no sunspots on the side of the Sun facing us at this time, however the solar hole seems to exist. Real-time X-ray Solar Flares data: http://www.sec.noaa.gov/rt_plots/xray_5m.html This GOES X-ray flux plot contains 5 minute averages of solar X-ray output in the 1-8 Angstrom (0.1-0.8 nm) and 0.5-4.0 Angstrom (0.05-0.4 nm) passbands. Coronal Mass Ejection information: http://lasco-www.nrl.navy.mil/index....ontent/cmelist LASCO Coronal Mass Ejections Lists Coronal Mass Ejections (CMEs) are massive (10^14 to 10^17 grams) bursts of plasma that are ejected from the sun. One of the scientific objectives of LASCO is to understand why these events occur. We do believe that they are caused by instabilities in the solar magnetic field, which is constantly evolving. Another scientific objective is to understand what effects CMEs have in interplanetary space and very importantly what effects CMEs have when they encounter the earth's environment. We know that the energetic CMEs will cause geomagnetic storms and possibly affect electric power transmission lines. Real-time data: http://lasco-www.nrl.navy.mil/index....ent/latest_img Listed below are links to the most recent realtime images from the LASCO and EIT instruments. |
#5
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Solar Hole?
On Thu, 15 Mar 2007 09:23:53 +0100, JeroenK wrote in
: Johnny Borborigmi schreef: Google CME or Coronal Mass Ejection and learn all about it. A coronal hole is something different from a CME. A CME is a solar flare, giant burst from the sun whike a coronal hole is a relatively cooler area of the sun (they appear dark in EIT images) that also have a higher release of particles then other area's from the sun. A CME generally has more impact on earth (if it was earth bound) then a CH, as more matter is released. Things are a bit oversimplified, but HTH So what sort of impact on radio propagation/reception should one expect a solar hole to impose? Does a solar hole result in only increasing the velocity of the solar wind without the massive increase in particle count that occurs during a CME event? |
#6
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Solar Hole?
Larry Dighera schreef:
So what sort of impact on radio propagation/reception should one expect a solar hole to impose? There are no holes in the sun, there are in the corona though. The correct term is Coronal Hole. My knowledge on propagation needs more deepening (although I have great interest in Aurora, hence my knowledge on these happenings). Although I have a base knowledge I hope someone else will chime in who has more knowledge to ensure I wont feed you nonsense Does a solar hole result in only increasing the velocity of the solar wind without the massive increase in particle count that occurs during a CME event? A CME is a massive flare with lots of particles released in sudden events, CHs are more of a steady stream of particles that is however lots lower in number of particles then a CME. This is debatable, but CH's should increase proper propagation, and CMEs can cause storms and as such actually stop propagation. But again, I hope someone with proper knowledge of spaceweather will chime in. -- JeroenK |
#7
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Solar Hole?
On Thu, 15 Mar 2007 12:26:08 +0100, JeroenK wrote in
: Larry Dighera schreef: So what sort of impact on radio propagation/reception should one expect a solar hole to impose? There are no holes in the sun, there are in the corona though. The correct term is Coronal Hole. You are correct. Thank you for calling my faux pas to my attention. My knowledge on propagation needs more deepening (although I have great interest in Aurora, hence my knowledge on these happenings). Although I have a base knowledge I hope someone else will chime in who has more knowledge to ensure I wont feed you nonsense Does a solar hole result in only increasing the velocity of the solar wind without the massive increase in particle count that occurs during a CME event? A CME is a massive flare with lots of particles released in sudden events, CHs are more of a steady stream of particles that is however lots lower in number of particles then a CME. This is debatable, but CH's should increase proper propagation, and CMEs can cause storms and as such actually stop propagation. But again, I hope someone with proper knowledge of spaceweather will chime in. Thank you for sharing your knowledge. It would seem from personal observation, that currently, during a CH event, the Maximum Useable Frequency (MUF) is considerably lower than normal, but that may be due solely to the Solar Minimum* we are currently experiencing. * http://en.wikipedia.org/wiki/Solar_minimum (Interesting predictions: http://science.nasa.gov/headlines/y2..._longrange.htm Long Range Solar Forecast 05.10.2006 Solar Cycle 25, peaking around 2022, could be one of the weakest in centuries. ... A team led by physicist Mausumi Dikpata of NCAR has predicted that Cycle 24, peaking in 2011 or 2012, will be intense. http://www.ucar.edu/news/releases/2006/sunspot.shtml http://science.nasa.gov/headlines/y2...ormwarning.htm "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.) |
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