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

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.

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

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.

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?

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

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.)