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#93
Issued on Tuesday April 18, 2017 at 1330 UTC
Global Daily HF Radio Wave
Propagation Forecast-
HAMATEUR & SW BROADCAST HF BANDS:
Global
generalized HF radio wave propagation conditions
are
poor to fair
on 17-80 (16-75) meters
and
very poor to poor on 12-10 (11)
meters.
NORTHERN HEMISPHERE RADIO WAVE PROPAGATION-
80-60 (75-60)
meters- fair at night and poor at day,
40-30 (41-25) meters- fair at
night and fair at day,
20-17 (22-16) meters- very poor at night and fair
at day,
15 (13) meters- very poor at night and poor at day,
12-10
(11) meters- very poor at night and very poor at day.
SOUTHERN HEMISPHERE
RADIO WAVE PROPAGATION-
80-60 (75-60) meters- fair at night and poor at
day,
40-30 (41-25) meters- fair at night and fair at day,
20-17
(22-16) meters- very poor at night and fair at day,
15 (13) meters- very
poor at night and poor at day,
12-10 (11) meters- very poor at night and
very 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
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
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.
---------------------------------------------------------------------------------------------
Solar,
Space & Geomagnetic Weather Conditions On
Monday April 17,
2017-
Solar activity was low.
Earth's geomagnetic field was
quiet.
The three daily solar flux index (SFI) numbers were 75.5 75.2
75.8.
The official daily sunspot number (SSN) was 0. This is the second
day in a
row with the big goose egg.
In 2017 officially there were 30
days with a daily sunspot number (SSN) of
0.
Considering that solar
minimum won't occur for approximately 2 more years,
+/- 1 year, observations
daily SSN's of 0 occurring now is unusually early.
No earth facing
sunspot groups were visible.
But unofficially there four earth facing but
as of yet unnumbered sunspot
groups. They were located
near
N09E46,
N24E69,
N12W13,
N11E85 and was probably returning
sunspot group #12644 which should get
renumbered today as 12651.
Two
earth facing C0.0 class or larger solar flares occurred. They
were
C2.0,
C3.3.
---------------------------------------------------------------------------------------------
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 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 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.
---------------------------------------------------------------------------------------------
No
earth directed coronal mass ejections (CME) occurred.
But a minor earth
directed coronal mass ejection (CME) was visible on
SOHO/LASCO imagery but
the plasma cloud was not (geoeffective) directly
aimed at earth.
No
earth directed collapsing magnetic filament eruptions occurred.
No earth
directed day side radio black outs occurred.
The twenty four hour period
3 hour interval planetary K index (Kp) was at
quiet geomagnetic conditions
of
0 0 1 0 1 0 1 1.
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
4 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 daily averaged
background x-ray flux was at C3.38.
The daily averaged vertical component
(Bz) of earth's magnetic field was at
+2.5 nT north.
The 24 hour
period maximum and minimum Dst ranged between
-11 and -1 nT.
The
24 hour period maximum and minimum solar wind speed ranged between
346
and 270 km/s.
There was a southern hemisphere (geoeffective) directly
earth facing (CH)
coronal hole #801. It produced minor (Kp-5) geomagnetic
storming during its
last trip across the earth facing side of the
sun.
There was a recurrent southern hemisphere earth facing (CH) coronal
hole
#802(#798). It produced moderate (Kp-6) geomagnetic storming during its
last
trip across the earth facing side of the
sun.
--------------------------------------------------------------------------------------
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
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.
