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Radio Propagation : Space Weather : Sunspot Cycle Information

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Gain the on-air edge: This article explains how the ANTENNA is the key! -> Read this introduction to Antenna Modeling



X-ray Conditions (Flares) 5-min.

X-ray plot

X-ray Conditions (Flares) 1-min.

X-ray plot

Geomagnetic Conditions (Kp)

plot of Kp

Satellite Environment Plot:

Satellite Environment Plot

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+ Aurora Resources

How-To Articles:

- Is HF Propagation Reciprocal?
- De-mystifying HF Radio Propagation and Modeling

Check out the ACE-HF propagation software - the latest is version 2.05. ACE-HF is propagation forecasting and modeling for Amateur Radio as well as for Shortwave radio Listening and general HF operation. This software is even used by the military and other clients around the world. This software is developed and maintained by the same engineers that keep VOACAP up-to-date. As a result, this software is the most accurate user interface integrated with VOACAP. CHECK IT OUT, TODAY. This software is the most accurate modeling software available, and is endorsed by NW7US. Read the details to find out why.

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Warnings/Alerts issued
in the last 24 hours, if any:

(Key: NOAA Scales)

[ live aurora display ]
[ auroral power maps ]

[ d-layer conditions ]

[ latest solar images 1 ]
[ latest solar images 2 ]
[ latest solar images 3 ]

[ active solar regions ]
[ current solar region image ]

[ What is a flare and its class? ]

Recent Space Environment Reports:

+ Reports of Solar & Geophysical Activity
+ Solar & Geophysical Activity Summaries

From the Space Environment Center:

Solar X-ray Flux

+ A 3 day plot of 5-minute solar X-ray flux values measured on the GOES 8 and 10 satellites.
+ A 6-hour 1-min Solar X-ray Flux plot

Satellite Environment Plot

[ Proton Flux ] [Electron Flux ]
[ GEOS Hp ] [ Estimated Kp ]

Additional Resources

+ SpaceW.com Aurora Network
+ D-Layer Absorption Conditions/Predictions
+ 160 Meter Propagation Forecast
+ Solar Physics Department of the Royal Observatory of Belgium, the official keepers of sunspot data.

Solar Activity Forecast
The Forecast of Solar Activity as well as Geomagnetic Activity

Probability of Flares
and Proton Events
0-24 hrs
24-48 hrs
Geomagnetic Activity Probabilities

Middle latitudes
High latitudes

0-24 hrs
24-48 hrs
0-24 hrs
24-48 hrs
Minor Storm
Major-severe Storm

Solar Sunspot Cycle 24 Progress

Solar Cycle 24 Smoothed Sunspot Progress
Solar Cycle 24 10.7-cm Monthly Progress
Solar Cycle 24 Planetary A Index (Ap) Monthly Progress
Do you want the latest solar conditions sent to you as an RSS feed? Click: XML RSS propagation feed

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(Use http://hfradio.org/propsupport/prop.rss as your RSS channel url)

This page was rendered on 20-May-24 1612 UTC.
This page was first created as HFRadio.org in the mid 1990s, and morphed here in 1998, by Tomas David Hood (NW7US)

Current Sunspot Cycle 25 Activity ~ Space Weather ~ Shortwave Radio Propagation

Sun Spots: 154 as of 05/19/2024 :: 10.7-cm Flux: 201 SFU
(SFU=Solar Flux Units)

Space Weather Overview Graphic from SWPC

30 Minutes of Dazzling Sun! Ultra-high Definition 4k View

An Intimate View of the Sun, Every Day of 2015 (Year 6 of SDO) UHD 4k

Watch Five Very Intense X-class X-ray Flares Erupt, Back-to-back!
(From the largest sunspot region in 20+ years...)

Check out the X2.7 X-ray Flare (May 5 2015) - 'Biggest' of 2015, so far

See highlights of the last five years of the Sun, as seen by SDO

The Solar Dynamics Observatory (SDO) Latest Solar Images
Click on an image for full-sized view

SDO - Solar Dynamics Observatory     SDO - Solar Dynamics Observatory

D Region Absorption Predictions (D-RAP) Global Map

Map, Above: Conditions in the D region of the ionosphere have a dramatic effect on high frequency (HF) communications and low frequency (LF) navigation systems. The global D Region Absorption Predictions (D-RAP) depicts the D region at high latitudes where it is driven by particles as well as low latitudes, where photons cause the prompt changes.

Note: At times, images may appear broken or missing, when SDO is working on the AIA/HMI instruments.

Planetary A-index (Ap): 9 | Planetary K-index (Kp): 2.33
Solar Wind: 367 km/s at 1.0 protons/cm3, Bz is 1.0 nT
(May 20, 2024 at 1602 UT)

X-ray Solar Flares:
6h hi [M2.5][1747Z 05/19] 24h hi [M2.5][1747Z 05/19]

Background X-ray Level, Last Six Days


Check out the current Aurora Oval and activity.

What is the difference between the CB and Amateur Radio Services, in the USA? Here are some thoughts on the portrayal of the Amateur Radio Service by the Hit TV Series, NCIS, and a clarification of the difference between CB radio and ham radio.
(Skip to timecode 1:33 to bypass the introductory chat and talk about the headset microphone.)

Here is a video introduction to shortwave / HF amateur radio -- what is it that we amateur radio oprators listen to? If you have not yet been introduced to this world, this is a very basic introduction.

If you are using software utilities such as Ace-HF, that require a "smoothed" sunspot number
(Referred to as the SSN), or, the smoothed 10.7-cm Radio Flux Index,
use the following predicted values in this following table:

To understand more about the Maximum Usable Frequencies, and related
science, please read the MUF Basics Page.

Global HF Propagation Conditions
Global HF Propagation Conditions for 0400Z on 05 May, 2021
High Latitude: Normal
Middle Latitude: Normal
Low Latitude: Normal

Geomagnetic Latitude Ranges:
High: 60-90 degrees
Middle: 20-60 degrees
Low: 0-20 degrees

At 0805 UTC, on 9 August 2011, a strong magnitude X6.9 X-ray flare -- the strongest yet in this current solar cycle (Cycle 24) -- erupted on the northwestern solar limb. Here is a HD Movie of the event:

Videos of Interest - Space Weather, Solar Dynamics Observatory, STEREO, and more... from the NW7US YouTube Channel. (Click on the small image to launch the video...)

Video: Voyager Finds Magnetic Foam at Solar Systems Edge
Video: Voyager Finds Magnetic Foam at Solar Systems Edge

Video: Zoom View of Prominence Eruption and X-Ray Flare - M2.5 Magnitude - June 7 2011
Video: Zoom View of Prominence Eruption and X-Ray Flare - M2.5 Magnitude - June 7 2011

Video: X-Ray Flare, Coronal Mass Ejection, Proton Storm - M2.5 Magnitude - June 7 2011
Video: X-Ray Flare, Coronal Mass Ejection, Proton Storm - M2.5 Magnitude - June 7 2011 (Close-up of the video, above)

Video: Stunning Close-up View of M3 X-Ray Flare 24 February 2011
Video: Stunning Close-up View of M3 X-Ray Flare 24 February 2011

Video: On How NCIS TV Show Maligned Amateur Radio Service (Full UHD Version)
Video: On How NCIS TV Show Maligned Amateur Radio Service (Full UHD Version)
What's the difference between CB and amateur (ham) radio?

Video: June 2011 20-meter (14-Mhz) JT65A Coverage Map of NW7US Radio Signal
Video: June 2011 20-meter (14-Mhz) JT65A Coverage Map of NW7US Radio Signal

The NW7US Current Sunspot and Geophysical Activity Report
The observations, prognastications, and comments by NW7US
NW7US is Tomas David Hood, Propagation and Space Weather Columnist
for CQ Communications

More about Background X-rays

The hard X-ray energy present from the wavelengths of 1 to 8 Angstroms provide the most effective ionizing energy throughout all of the ionospheric layers in our atmosphere. The GEOS satellites measure these wavelengths and the resulting measurements are reported as the "background X-ray level" throughout the day. A daily average is reported, as well.

Just like X-ray flares, the background hard X-ray level is measured in watts per square meter (W/m2), reported using the categories, A, B, C, M, and X. These letters are multipliers; each class has a peak flux ten times greater than the preceding one. Within a class there is a linear scale from 1 to 9.

If one records the daily background X-ray levels for the course of a sunspot cycle, one would discover that the background X-ray levels remained at the A class level during the sunspot cycle minumum. During the rise and fall of a solar cycle, the background X-ray energy levels remained mostly in the B range. During peak solar cycle periods, the background energy reached the C and sometimes even M levels.

Armed with this information, can we discover any clues as to the current status of Sunspot Cycle 24? Below is a graph plotting the background hard X-ray energy reported by the GEOS satellites since the end of Sunspot Cycle 22. Clearly, we see a noticeable rise in Cycle 24 activity. We're seeing the energy mostly in the B level more often, supporting the view that Cycle 24 is alive and moving along toward an eventual sunspot cycle peak in several years.

Overall, the monthly average background 'hard' X-ray level is rising (as seen by the following plot), showing a change from deep solar cycle minimum. We are certainly in the rising phase of Sunspot Cycle 24. While it has been a slow up-tick over the last eighteen months, I expect to see a more rapid rise during mid to late 2011.

Background X-ray (1 to 8 Angstrom) Plot

Highlights of Solar and Geomagnetic Activity
Covering the period: 13 - 19 May 2024

Solar activity ranged from low to high levels during the period. High levels were reached 13-15 May; moderate levels 16-17 May; and low levels on 18 May. Levels returned to moderate by 19 May. There were at least 15 M-class flares and 5 X-class flares during the reporting week - sub-peaks and re-enhancements made firm correlations difficult. Region 3664 (S17, L=347, Fkc/BGD on 11 May) was the primary X-class flare producer and erupted with the largest solar flare thus far in solar cycle 25, an X8.7 at 14/1651 UTC as it reached the western limb. Nineteen sunspot groups littered the solar disk, with Region 3664 rotating beyond the limb 14 May. Even though Region 3664 rotated beyond the limb, it continued producing M and X-class flares on 15 May, to include an X3.4 flare at 15/0818 UTC. Another active region just beyond the east limb was the source of an X2.9 flare on 15/1438 UTC. This region rotated into view on 16 May and was designated as Region 3685 (S13 L=152, Ehi/BG on 16 May.

Radio activity was aplenty during the week - main highlights include Region 3664 eruption of solar radio bursts on 14 May that included Castelli U signature bursts twice, once with an X1.7 flare at 14/0209 UTC and again with the X8.7 flare. The first radio burst was the more massive, with a peak frequency flux centered on 245 MHz of 63,000 sfu. Tenflares were also observed, as well as Type II and IV radio sweeps with each of these events. Radio activity of note continued on 15 May with early activity still from well beyond the limb Region 3664, however, later on 15 May, the source region shifted to the east limb, with Type II and IV sweeps associated with the X2.9 flare from soon to be assigned Region 3685.

Many CMEs were noted through the week, most were sourced to Region 3664 and were determined to be misses ahead of Earth. However, even though an asymmetric halo CME on 13 May from Region 3664 was analyzed and modeled as mainly a miss, possible shock arrival and glancing or near-proximity influences were possible on 14-15 May due to its fast speed. Additionally, on 14 May, a filament eruption centered over the far northeastern solar disk was modeled and a glancing blow was suggested by 17 May. Yet another filament eruption occurred from a source location in the northwest quadrant on 16 May. This associated CME analysis and model results suggested a glancing blow possible on 20 May.

A proton event was observed at geosynchronous orbit. The event began on 13 May as the greater than 10 MeV levels reached 10 pfu at 13/1400 UTC and breached 100 pfu by 14/0335 UTC. These events were most likely associated with flare and CME activity from region 3664. Peak flux reached was 121 pfu on 14/0505 UTC and decreased below 10 pfu at 16/1455 UTC.

The greater than 2 MeV electron flux reached 1,000 pfu on 15/1525 UTC with a peak flux of 1,500 pfu at 15/1840 UTC and returned to normal levels on 16 May.

Geomagnetic field activity ranged from quiet to G2 (Moderate) storm levels. 13 May began with G2 levels in response to continued CME influences as solar wind speeds were still highly elevated and near 850 km/s with total IMF strength between 5-10 nT and favorable periods of southward Bz component. Solar wind speed slowly declined and eventually reached near 450 km/s on 15 May, while the total IMF strength weakened and returned to more ambient levels. This led to a period of mainly quiet to unsettled levels 14-15 May. Another enhancement in the solar wind field occurred on 16 May due to CME effects (likely from one of Region's 3664 CMEs of 13 May) as total field intensified to 17 nT, while the Bz component shifted southward - this led to G1 (Minor) to G2 storm levels. Yet another CME arrival disturbed and enhanced the IMF again, with a favorable southward connection on 17 May that led to G1-G2 storm levels again. The origin of this CME is somewhat in doubt, but the most likely candidate is one of the CMEs from Region 3664 on 14 May. The solar wind field gradually returned to a less disturbed and more ambient, background state on 18 May with quiet to active levels noted and quiet to unsettled conditions on 19 May.

Monthly and smoothed sunspot number - The monthly mean sunspot number (blue) and 13-month smoothed monthly sunspot number (red) for the last five cycles. You can see that this current cycle, Cycle 24, is a weak cycle, compared to the last few.

(Click to see actual size)
Monthly and smoothed sunspot number chart

Daily and monthly sunspot number (last 13 years)

Daily sunspot number (yellow), monthly mean sunspot number (blue), smoothed monthly sunspot number (red) for the last 13 years and 12-month ahead predictions of the monthly smoothed sunspot number:

SC (red dots) : prediction method based on an interpolation of Waldmeier's standard curves; It is only based on the sunspot number series.

CM (red dashes) : method (from K. Denkmayr and P. Cugnon) combining a regression technique applied to the sunspot number series with the aa geomagnetic index used as a precursor (improved predictions during the minimum phase between solar cycles).

(Click to see actual size)
Daily and monthly sunspot number (last 13 years)

What is 'Space Weather'? Click on these two information slides to view them in full size:

What is Space Weather? Slide 1 of 2 What is Space Weather? Slide 2 of 2

View of numbered sunspot regions and plages (if any)
Source: http://www.solarmonitor.org/.
(Click for large view)

Active Regions and Plages

Active sunspot regions, and plages, identified by SIDC

SIDC Solar Disc with active regions and plages

STEREO Behind Image
What is coming
SOHO EIT 195 Image
Current View
STEREO Ahead Image
What was...

Real Time Solor Wind and Aurora:

On 2024 May 20 1602Z: Bz: 0.6 nT
Bx: -4.4 nT | By: 4.7 nT | Total: 6.5 nT
Most recent satellite polar pass:
Centered on // : UTC
Aurora Activity Level was at UTC
visit noaa for latest.

This is a video of the simulation from May 27-28, 2011, showing
the Geomagnetic disturbance caused by the solar wind

Space Weather and Propagation Forecast
Prepared by the US Dept. of Commerce, NOAA,
and the Space Weather Prediction Center

Three Day Forecast of Solar and Geomagnetic Activity
(as of 2200Z on 07 Dec 2014)

Solar Forecast:

Solar activity is expected to be low with a chance for M-class flares on days one, two, and three (08 Dec, 09 Dec, 10 Dec).

Geomagnetic Forecast:

The geomagnetic field is expected to be at quiet to minor storm levels on day one (08 Dec), quiet to active levels on day two (09 Dec) and quiet levels on day three (10 Dec).

Forecast of Solar and Geomagnetic Activity
20 May - 15 June 2024

Solar activity is likely to be moderate (R1-R2; Minor-Moderate), with a slight chance for high levels (R3; Strong) through 21 May as Region 3685 (S13 L=155, Ehi/BG as of 18 May) continues to produce low-level M-class flares (R1). The region will take some time to rotate to the western limb - rotating beyond the limb by 30 May. Meanwhile eight other regions will rotate beyond the limb beginning 21 May through 26 May. A good number of former spot regions are timed to rotate back into Earth-view through much of the outlook period - the most anticipated is former Region 3664 (S17, L=347, Fkc/BGD on 11 May) that is expected to return by 26-27 May. The litany of returning regions, to include 3664, could lead to increasing solar activity levels back to moderate to high levels as early as 26 May.

There will be a slight chance of S1 (Minor) solar radiation storms through 30 May until Region 3685 rotates beyond the western limb. If Region 3664 survives to its return to the visible solar disk 26-27 May, there is a possibility of an increase to a chance of an S1 storm by 7-15 June.

The greater than 2 MeV electron flux is likely to be normal to moderate with a chance for high levels 20 May - 15 Jun.

Geomagnetic activity is anticipated to be at quiet to active conditions, with likely G1 (Minor) storm levels 20 May due to CME effects. Conditions are expected to wane on 21 May and primarily quiet to active levels are expected. A period of quiet conditions follows 22-23 May, with CH HSS effects leading back to active levels 24-25 May. The remainder of the period is anticipated to be primarily a mix of quiet to active conditions in varying response to occasional recurrent CH HSS effects.

Real-time foF2 map from IPS (Ionospheric Prediction Service), Australian Space Weather Agency

foF2 Map from IPS, Australia

Space Weather + Ham Radio Resources

Click on image to
view larger versions

The following images
are from SOHO

C2 LASCO Image
C3 LASCO Image

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Additional Views of the Sun

Be sure to check the Date shown in each photo - is it today's date?
(click to enlarge)

Current Numbered Sunspots / MDI MagnetogramCatania Solar Disc

H-Alpha View 1H-Alpha View 2

Data and images courtesy of IPS Australia, NOAA, NASA, SWPC, SIDC

Layout, analysis, commentary, and certain forecasts and content is
Copyright, 2022, Tomas David Hood (NW7US), all rights reserved.
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Last Update: November 21, 2022