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#64 Issued on Wednesday March 15, 2017 at 1400 UTC
Global HF Radio Wave Propagation Forecast
HF radio wave propagation conditions are fair to good on 17-80 meters.
HAMATEUR & SW BROADCAST HF BANDS:
NORTHERN HEMISPHERE RADIO WAVE PROPAGATION-
80-60 (75-60) meters- good at night and poor at day,
40-30 (41-25) meters- good at night and fair at day,
20-17 (22-15) meters- very poor at night and good at day,
15 (13) meters- very poor at night and fair to good at day,
12 (11) meters- very poor at night and fair at day.
10 (11) meters- very poor at night and poor to fair at day.
SOUTHERN HEMISPHERE RADIO WAVE PROPAGATION-
80-60 (75-60) meters- poor at night and very poor at day,
40-30 (41-25) meters- fair at night and poor at day,
20-17 (22-15) meters- fair at night and fair at day,
15 (13) meters- poor at night and fair at day,
12(11) meters- very poor at night and poor to fair at day.
10 (11) meters- very poor at night and poor at day.
Received RF signal strength scale-
Very Good- +1 over S9 Or Greater
Very Poor- S0
Meter Band Equivalents
Ham & SWL
40-> 49, 41
30-> 31, 25
20-> 22, 19
17-> 16, 15
Please keep in mind that this is a relatively simplified HF radio wave
propagation forecast, so as to keep it easily understandable by the average
Globally HF radio wave propagation conditions are most evenly balanced
during the fall and spring equinoxes and most diametrically opposed during
the summer and winter solstices.
Conditions also change daily, weekly, monthly, yearly and by decade, as the
sun rises and sets at different times and at different angles from the
ecliptic, as well as by radio wave frequency. This is due to changes in the
maximum usable frequency (MUF), lowest usable frequency (LUF) and F layer
critical frequency (FoF2).
The D and E layers also come into play through RF radio wave signal
absorption and refraction. And then there is sporadic E (Es) radio wave
propagation that can really throw a wrench into the gears so to speak.
Things like sporadic E (Es) radio wave propagation and lightning storm
static can impact HF radio wave propagation in an unpredictable manner and
Ongoing solar, space and geomagnetic weather goings on also impact HF radio
wave propagation conditions in a negative manner.
Solar Space & Geomagnetic Weather Conditions On
Tuesday March 14, 2017-
Solar activity was very low.
Earth’s geomagnetic field was quiet.
The three daily solar flux index (SFI) numbers were 69.9 69.6 70.2.
The official daily sunspot number (SSN) was 0. This is the 9th day in a row
with the big goose egg.
There were no earth facing sunspot groups.
But today unofficially and as of yet unnumbered sunspot group was located
If this sunspot group survives, which I doubt it will, it could end the 9
day consecutive streak with no daily earth facing sunspot numbers.
In 2017 officially there were 22 days with a daily sunspot number (SSN) of
Considering that solar minimum won’t occur for approximately 2 more years,
+/- one year, seeing daily SSN’s of 0 occurring now is unusually early.
In 2016 officially there were 32 days with a daily sunspot number (SSN) of
0. Considering that solar minimum won’t occur for approximately three more
years, seeing daily SSN’s of 0 occurring now is unusually early.
As we move forward towards the next solar minimum between solar cycle #24
and #25 the number of days with a 0 daily SSN will steadily increase.
Eventually every day for many many many months will see a 0, the big goose
In 2008 I fore casted solar cycle 24 to be the weakest in the past 100 years
and that forecast verified. I also fore casted that solar cycle 25 would be
virtually non existent, similar to the Dalton type solar minimum that
occurred in the early 1800’s. It will probably be very difficult to
determine when solar cycle 24 ended and solar cycle 25 began.
No earth directed coronal mass ejections (CME) occurred.
No earth directed collapsing magnetic filament eruptions occurred.
The twenty four hour period 3 hour interval planetary K index (Kp) was at
quiet geomagnetic conditions of
1 2 1 1 1 1 1 1.
The Kp geomagnetic indices are-
5- minor geomagnetic storming
10- our atmosphere just got cooked off like on Mars and we are all dead.
The 24 hour period maximum and minimum planetary A index (Ap) ranged between
6 and 3,
which was at quiet geomagnetic conditions.
The Ap geomagnetic indices are-
30-49- minor geomagnetic storm
>401- our atmosphere just got cooked off like on Mars and we are all dead.
The daily averaged background x-ray flux was A1.0.
The daily averaged vertical component (Bz) of earth’s magnetic field was
+4.3 nT north.
The maximum and minimum Dst ranged between -12 and -3.
The maximum and minimum solar wind speed ranged between
353 and 325 km/s.
There was a northern hemisphere earth facing (CH) coronal hole #796. But it
continues to decay and may close in the next two days.
There was a recurrent trans equatorial earth facing (CH) coronal hole #797
(#771). During it’s last passage on the earth facing side of the sun it
impacted earth’s geomagnetic field in a negative manner.
GENERAL GUIDELINES CONCERNING CORRELATION OF PROPAGATION INDICES TO ACTUAL
HF PROPAGATION CONDITIONS-
NOTE!!! The propagation indices “interpretations” are my personal
intellectual property. Therefore the radio wave propagation indices
interpretations contained herein is copyrighted © 1988-2017 by Thomas F.
Giella, W4HM, all rights reserved. Reproduction of information herein is
allowed without permission in advance as long as proper credit is given.
All 14 of the following indices have to occur as described below in order to
see the best global high frequency radio wave propagation possible.
Something that happens rarely.
1.) Dropping geomagnetic field indices numbers are better, Kp of 0 best.
2.) A daily sunspot number of 150 or higher, 200 or higher best.
3.) A daily sunspot number of greater than 100 for routine stable formation
of the E Valley/F Layer ducting mechanism.
4.) Previous 24 hour Ap index under 10, fewer than 7 for several days
consecutively are best.
5.) Previous 3 hours Kp index fewer than 3 for mid latitude paths, fewer
than 2 for high latitude paths, 0 for several days consecutively is best.
6.) Energetic protons no greater than 10 MeV (10+0).
7.) Background x-ray flux levels greater than B1 for several days
consecutively, greater than C1 best.
8.) No current STRATWARM alert.
9.) Interplanetary magnetic field (IMF) Bz with a (positive number) sign,
indicates a lesser chance of high latitude path aurora
absorption/unpredictable refraction or scattering of medium frequency RF
signals, when the Kp is above 3.
10.) A -10 or better towards a positive number Dst index during the recovery
time after a geomagnetic storm, as related to the equatorial ring current. A
positive number is best.
11.) Rising positive T index number. The T Index tracks with the F2 layer
critical frequency (foF2) and sunspot number (SSN) and indicates the
capability of the F2 layer to refract RF signals.
12.) Galactic cosmic rays decrease to -3 units below zero and trending
13.) Energetic electron flux levels no greater than 2 MeV (2+0).
14. A solar wind speed of less than 300 km/s for several days consecutively.
Note! I use error prone RAW public domain data from the NOAA Space
Environment Center, other U.S. government entities and educational
institutions, to produce my comprehensive HF radio wave propagation
forecast. This data is gathered and made public by the U.S. Government using
taxpayer $$$ (including mine).
However the propagation forecast that I produce from the RAW public domain
data is my personal intellectual property. Therefore this radio wave
propagation forecast contained herein is copyrighted © 1988-2017 by Thomas
F. Giella, W4HM.
Feel free to redistribute this solar, space and geomagnetic weather
discussion and HF radio wave propagation forecast, as long as you
redistribute it in it’s entirety and give me credit for it.
Also solar, space and geomagnetic weather forecasting is still an inexact
science. The forecasts are not official but for educational and hobby
related purposes only and are subject to human error and acts of God,
therefore no guarantee or warranty implied.