Topband: auroral images

[k9la at frontier.com]

Paul N1BUG commented:
"While on the subject, I never have liked, and still do not, the ever popular NOAA POES Auroral Activity plots at http://www.swpc.noaa.gov/pmap/index.html. These have to me proven very unreliable for the intended purpose of correlating to VHF auroral propagation, but also do not track as well with intensity of real time auroral disturbances at MF and HF."
 
I can understand Paul’s comments. Although the text at the web site of these auroral images says they can be used for a best-guess estimate of the geographic locations of the radio propagation paths that may be degraded, when you dig into the details of the measurements that produce these images, it's doubtful that these will be of any specific help at all. The issue is the detectors on board only measure low energy electrons that cause visual aurora, not the higher enegry ones that get down to lower altitudes to cause radio problems. What the images depict is statistically where visible aurora can occur based on the measurement of the over-flying satellite. The images are not "real time", either – based on the satellite's measurements, 1 of 10 canned pictures is pulled and displayed.
Many believe the auroral zone is full of detrimental ionization based on these images. Comparing these images to DMSP satellite images at the same time generally shows a narrow intense band of aurora (from the DMSP satellite) as opposed to widespread auroral ionization (suggested by the POES images). These intense bands may or may not affect VHF propagation depending on the intensity and location.
 
For more details visit http://myplace.frontier.com/~k9la, select the General link on the left, and read "A Look Inside the Auroral Zone".
 
Carl K9LA