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#117
Issued on Thursday April 27, 2017 at 1400 UTC
Global Daily HF Radio Wave
Propagation Forecast-
HAMATEUR & SW BROADCAST HF BANDS:
HF
radio wave propagation conditions are slowly improving.
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- 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.
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
The SSB RF signal levels received are based on 100 watts and ½ wave
dipole
up at 40 feet for hamateur radio.
The AM signal levels on the
HF shortwave broadcast bands are based on
100,000 watts (100 kw) and a
typical 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 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
Wednesday April 26,
2017-
Solar activity was low.
Earth's geomagnetic field was at an
unsettled level.
The three daily solar flux index (SFI) numbers were 81.7
79.6
78.5.
---------------------------------------------------------------------------------------------------------------------
The
official daily sunspot number (SSN) was 36.
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.
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.
---------------------------------------------------------------------------------------------------------------------
The
twenty four hour period 3 hour interval planetary K index (Kp) was at
unsettled to quiet geomagnetic conditions of
3 1 2 1 2 2 2
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 5,
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 daily averaged
background x-ray flux was at B4.96.
The daily averaged vertical component
(Bz) of earth's magnetic field was at
+0.84 nT north.
The 24 hour
period maximum and minimum disturbance storm time index (Dst)
ranged
between
-20 and -38 nT.
The 24 hour period maximum and minimum
solar wind speed ranged between
568 and 451 km/s
and was directly
connected by a high speed solar wind stream to recurrent
southern hemisphere
earth facing (CH) coronal hole #802 (#798).
CH #802 (#798) produced
moderate (Kp-6) geomagnetic storming during its last
trip across the earth
facing side of the sun and has done so this time
around
also.
--------------------------------------------------------------------------------------
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.
