[W4HM Spaceweather] W4HM Daily HF Radio Wave Propagation Forecast #137
Thomas F. Giella
thomasfgiella at gmail.com
Wed May 17 11:03:36 EDT 2017
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#137 Issued on Wednesday May 17, 2017 at 1500 UTC
We are now moving into the summer/winter solstice type of HF radio wave
propagation conditions.
This means generally poor HF radio wave propagation conditions in the
northern hemisphere especially at day and generally good HF radio wave
propagation conditions in the southern hemisphere especially at day.
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 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).
Global Daily HF Radio Wave Propagation Forecast-
HAMATEUR & SW BROADCAST HF BANDS-
NORTHERN HEMISPHERE RADIO WAVE PROPAGATION-
80-60 (75-60) meters- poor to fair 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.
SOUTHERN 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 at day.
Received RF signal strength scale-
Very Good- +1 over S9 Or Greater
Good- S7-9
Fair- S4-6
Poor- S1-3
Very Poor- S0
Meter Band Equivalents
Ham & SWL
160-> 90
80-> 75
60-> 60
40-> 49, 41
30-> 31, 25
20-> 22, 19
17-> 16, 15
15-> 13
12,10-> 11
This HF Radio wave propagation forecast is based on the W4HM_Cap HF radio
wave propagation prediction software.
The hamateur radio JT65A mode RF signal levels received are based on 5 watts
and ½ wave dipole up at 40 feet.
The hamateur radio PSK31 mode RF signal levels received are based on 25
watts and ½ wave dipole up at 40 feet.
The hamateur radio CW mode RF signal levels received are based on 50 watts
and ½ wave dipole up at 40 feet.
The hamateur radio SSB RF mode signal levels received are based on 100 watts
and ½ wave dipole up at 40 feet.
The HF shortwave broadcast band AM Mode RF signal levels are based on
100,000 watts (100 kw) and a typical VOA type curtain array antenna.
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Please keep in mind that this is a relatively simplified HF radio wave
propagation forecast, so as to keep it easily understandable and applicable
by the average radio enthusiast.
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
mostly bad.
Ongoing solar, space and geomagnetic weather goings on also impact HF radio
wave propagation conditions in a negative manner.
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Solar, Space & Geomagnetic Weather Conditions On
Tuesday May 16, 2017-
Solar activity was very low.
Earth's geomagnetic field was at an unsettled level.
The three daily solar flux index (SFI) numbers were 71.0 71.9 70.7.
The official daily sunspot number (SSN) was 23.
The 7 days in a row streak with no earth facing sunspot groups finally came
to an end.
In 2017 officially there were 37 days with a daily sunspot number (SSN) of
0.
Considering that solar minimum won't occur for approximately 2 more years,
+/- 1 year, daily SSN's of 0 are occurring now 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
egg.
In 2008 I forecasted solar cycle 24 to be the weakest in the past 100 years
and that forecast verified. I also forecasted that solar cycle 25 would be
virtually nonexistent, 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.
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There were 2 newly risen or emerged official sunspot groups.
Sunspot group #12656 was located near N10E65 with a magnetically simple
alpha magnetic signature.
Sunspot group #12657 was located near N06E21 with a magnetically simple
alpha magnetic signature.
There was 1 unofficial and as of yet unnumbered earth facing sunspot group
located near
S08E67.
No earth facing C class or larger solar flares occurred.
No day side high latitude solar fade outs (SF) occurred.
The solar fade outs (SF) are also called polar cap absorption (PCA) mostly
caused by energetic protons striking earth’s geomagnetic field and
increasing RF signal absorption in the D layer.
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
unsettled to quiet geomagnetic conditions of
2 2 3 2 3 1 1 2.
The Kp geomagnetic indices are-
0-2- quiet
3- unsettled
4- active
5- minor geomagnetic storming
6- moderate
7- strong
8- severe
9- extreme
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
12 and 3,
which was at unsettled to quiet geomagnetic conditions.
The Ap geomagnetic indices are-
0-7- quiet
8-15 unsettled
16-29- active
30-49- minor geomagnetic storm
50-99- major
100-400- severe
>401- our atmosphere just got cooked off like on Mars and we are all dead.
The 24 hour period averaged energetic proton flux was at a background level
below 10 MeV.
The 24 hour period averaged background x-ray flux was at B1.25.
The 24 hour period averaged vertical component (Bz) of earth's geomagnetic
magnetic field was at
+1.63 nT north.
The 24 hour period maximum and minimum disturbance storm time index (Dst)
ranged between
+10 and -7 nT.
The 24 hour period maximum and minimum solar wind speed ranged between
606 and 530 km/s
and was directly attached via a high speed solar wind stream (HSS) to
recurrent trans equatorial coronal hole (CH) #803 (#801).
There was a recurrent trans equatorial earth facing coronal hole (CH) #803
(#801).
There was a recurrent directly earth facing (geo effective) and growing in
size trans equatorial coronal hole (CH) #804 (#802). It produced minor
(Kp-5) geomagnetic storming during its last trip across the earth facing
side of the sun.
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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
towards zero.
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.
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Standard Disclaimer-
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 solar, space and geomagnetic discussions as well as the HF
propagation forecast that I produce from the RAW public domain
data is my personal intellectual property. Therefore the solar, space and
geomagnetic weather discussions and HF radio wave
propagation forecast contained herein is copyrighted © 1988-2017 by Thomas
F. Giella, W4HM.
Feel free without advanced permission to redistribute this "not for profit"
solar, space and geomagnetic weather discussion and HF radio wave
propagation forecast, as long as you redistribute it in its 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.
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