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#145 Issued on Thursday May 25, 2017 at 1400
UTC
We are now 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 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.
---------------------------------------------------------------------------------------------------------------------
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 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
Wednesday May 24, 2017-
Solar activity was low.
Earth's geomagnetic field was at a quiet
level.
The three daily solar flux index (SFI) numbers were 77.7
77.9 78.3.
The official daily sunspot number (SSN) was 15.
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. Other than sunspot
magnetic polarity it will probably be very difficult to determine when solar
cycle 24 ended and solar cycle 25 began.
---------------------------------------------------------------------------------------------------------------------
There were 2 newly risen or emerged official sunspot
groups.
Sunspot group #12659 was located near N13W18 with a
magnetically simple beta magnetic signature.
Sunspot group #12660 was located near S09W40 with a
magnetically simple beta magnetic signature.
There were 2 unofficial and as of yet unnumbered earth
facing sunspot groups located near
S07W07,
N15W68.
No earth facing C class or larger solar flares
occurred.
No day side high latitude solar fade outs (SFO)
occurred.
The solar fade out (SFO) events are related to polar cap
absorption (PCA) occurrences mostly caused by energetic protons striking earth’s
geomagnetic field and increasing RF signal absorption in the D layer at high
latitudes.
No earth facing coronal mass ejections (CME)
occurred.
No earth facing collapsing magnetic filament eruptions
occurred.
The twenty four hour period 3 hour interval planetary K
index (Kp) was at quiet geomagnetic conditions of
1 1 1 1 1 1 0
0.
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
5 and 2,
which was at 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
B3.81.
The 24 hour period averaged vertical component (Bz) of
earth's geomagnetic magnetic field was at
-0.50 nT south.
The 24 hour period maximum and minimum
disturbance storm time
index (Dst) ranged between
-12 and +4 nT.
The 24 hour period maximum and minimum solar wind speed
ranged between
483 and 352 km/s.
There was a new earth facing northern hemisphere coronal hole #805. It became directly earth facing (geoeffective) on Tuesday May 23, 2017. However as it’s located at a high latitude position on the earth facing side of the sun and beginning to dissipate, it probably won’t impact earth’s geomagnetic field in a negative way.
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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.
------------------------------------------------------------------------------------
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.