Space weather

Solar wind speed Solar wind magnetic fields Noon 10.7cm radio flux
Bt Bz

Update

Update

Update
CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 2020-02-21 12.59 UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3021
Begin Time: 2020 Feb 20 1625 UTC
Yesterday Maximum 2MeV Flux: 2790 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Geomagnetic K-index of 4
Issued: 2020-02-21 01.19 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Feb 21 0115 UTC
Synoptic Period: 0000-0300 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-21 00.17 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Feb 21 0015 UTC
Valid To: 2020 Feb 21 0900 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 2020-02-20 16.43 UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Threshold Reached: 2020 Feb 20 1625 UTC
Station: GOES16


Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-19 08.43 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3711
Valid From: 2020 Feb 18 1305 UTC
Now Valid Until: 2020 Feb 19 1800 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 5 expected
Issued: 2020-02-19 06.00 UTC
Geomagnetic K-index of 5 expected
Extension to Serial Number: 1548
Valid From: 2020 Feb 18 1400 UTC
Now Valid Until: 2020 Feb 19 0900 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 5
Issued: 2020-02-19 06.00 UTC
Geomagnetic K-index of 5
Threshold Reached: 2020 Feb 19 0559 UTC
Synoptic Period: 0300-0600 UTC

Active Warning: Yes
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 4
Issued: 2020-02-19 03.59 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Feb 19 0358 UTC
Synoptic Period: 0300-0600 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 5 expected
Issued: 2020-02-18 18.15 UTC
Geomagnetic K-index of 5 expected
Extension to Serial Number: 1547
Valid From: 2020 Feb 18 1400 UTC
Now Valid Until: 2020 Feb 19 0600 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-18 18.14 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3710
Valid From: 2020 Feb 18 1305 UTC
Now Valid Until: 2020 Feb 19 0900 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WATCH
Geomagnetic Storm Category G1 Predicted
Issued: 2020-02-18 18.09 UTC
Geomagnetic Storm Category G1 Predicted

Highest Storm Level Predicted by Day:
Feb 19: G1 (Minor) Feb 20: None (Below G1) Feb 21: None (Below G1)

THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 5 expected
Issued: 2020-02-18 13.37 UTC
Geomagnetic K-index of 5 expected
Valid From: 2020 Feb 18 1400 UTC
Valid To: 2020 Feb 18 2100 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-18 13.06 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Feb 18 1305 UTC
Valid To: 2020 Feb 18 2100 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 2020-02-18 07.30 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Feb 18 0729 UTC
Synoptic Period: 0600-0900 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-18 06.52 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Feb 18 0651 UTC
Valid To: 2020 Feb 18 1200 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 2020-02-11 13.33 UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3019
Begin Time: 2020 Feb 08 1335 UTC
Yesterday Maximum 2MeV Flux: 6022 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 2020-02-10 10.36 UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3018
Begin Time: 2020 Feb 08 1335 UTC
Yesterday Maximum 2MeV Flux: 3816 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

CONTINUED ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 2020-02-09 12.21 UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3017
Begin Time: 2020 Feb 08 1335 UTC
Yesterday Maximum 2MeV Flux: 4380 pfu

Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Electron 2MeV Integral Flux exceeded 1000pfu
Issued: 2020-02-08 14.00 UTC
Electron 2MeV Integral Flux exceeded 1000pfu
Threshold Reached: 2020 Feb 08 1335 UTC
Station: GOES16


Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.

ALERT
Geomagnetic K-index of 4
Issued: 2020-02-08 00.01 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Feb 07 2359 UTC
Synoptic Period: 2100-2400 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-07 23.12 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Feb 07 2315 UTC
Valid To: 2020 Feb 08 0900 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-07 02.52 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3706
Valid From: 2020 Feb 06 2019 UTC
Now Valid Until: 2020 Feb 07 1800 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 5 expected
Issued: 2020-02-06 20.30 UTC
Geomagnetic K-index of 5 expected
Valid From: 2020 Feb 06 2030 UTC
Valid To: 2020 Feb 06 2359 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

ALERT
Geomagnetic K-index of 4
Issued: 2020-02-06 20.21 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Feb 06 2021 UTC
Synoptic Period: 1800-2100 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-06 20.19 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Feb 06 2019 UTC
Valid To: 2020 Feb 07 0300 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 2020-02-06 07.24 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Feb 06 0723 UTC
Synoptic Period: 0600-0900 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-02-06 06.51 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Feb 06 0650 UTC
Valid To: 2020 Feb 06 1200 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-01-31 05.02 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3703
Valid From: 2020 Jan 30 1650 UTC
Now Valid Until: 2020 Jan 31 0900 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 2020-01-31 04.59 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Jan 31 0459 UTC
Synoptic Period: 0300-0600 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-01-31 02.53 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3702
Valid From: 2020 Jan 30 1650 UTC
Now Valid Until: 2020 Jan 31 0600 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-01-30 23.36 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3702
Valid From: 2020 Jan 30 1650 UTC
Now Valid Until: 2020 Jan 31 0600 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

EXTENDED WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-01-30 20.56 UTC
Geomagnetic K-index of 4 expected
Extension to Serial Number: 3701
Valid From: 2020 Jan 30 1650 UTC
Now Valid Until: 2020 Jan 30 2359 UTC
Warning Condition: Persistence

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

ALERT
Geomagnetic K-index of 4
Issued: 2020-01-30 18.11 UTC
Geomagnetic K-index of 4
Threshold Reached: 2020 Jan 30 1759 UTC
Synoptic Period: 1500-1800 UTC

Active Warning: Yes

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-01-30 16.49 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Jan 30 1650 UTC
Valid To: 2020 Jan 30 2100 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

WARNING
Geomagnetic K-index of 4 expected
Issued: 2020-01-29 02.34 UTC
Geomagnetic K-index of 4 expected
Valid From: 2020 Jan 29 0233 UTC
Valid To: 2020 Jan 29 0600 UTC
Warning Condition: Onset

Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

Table

Date Radio flux 10.7 cm SESC Sunspot number Sunspot area 10E-6 New regions GOES15 X-ray Bkgd flux Flares
X-ray Optical
C M X S 1 2 3
2020-01-22 72 0 0 0 A8.1 0 0 0 0 0 0 0
2020-01-23 71 0 0 0 A7.6 0 0 0 0 0 0 0
2020-01-24 71 12 10 1 A7.5 0 0 0 0 0 0 0
2020-01-25 73 14 20 0 A7.5 0 0 0 1 0 0 0
2020-01-26 75 18 60 0 A8.0 0 0 0 1 0 0 0
2020-01-27 73 12 100 0 A8.1 0 0 0 0 0 0 0
2020-01-28 74 11 70 0 A8.1 0 0 0 0 0 0 0
2020-01-29 74 11 60 0 A8.1 0 0 0 0 0 0 0
2020-01-30 74 11 60 0 A8.2 0 0 0 0 0 0 0
2020-01-31 74 11 20 0 A8.1 0 0 0 0 0 0 0
2020-02-01 73 11 10 0 A7.9 0 0 0 0 0 0 0
2020-02-02 72 0 0 0 A7.9 0 0 0 0 0 0 0
2020-02-03 72 0 0 0 A8.1 0 0 0 0 0 0 0
2020-02-04 70 0 0 0 A7.9 0 0 0 0 0 0 0
2020-02-05 71 0 0 0 A7.9 0 0 0 0 0 0 0
2020-02-06 71 0 0 0 A8.0 0 0 0 0 0 0 0
2020-02-07 71 0 0 0 A8.3 0 0 0 0 0 0 0
2020-02-08 72 0 0 0 A8.4 0 0 0 0 0 0 0
2020-02-09 71 0 0 0 A8.2 0 0 0 0 0 0 0
2020-02-10 70 0 0 0 A8.1 0 0 0 0 0 0 0
2020-02-11 71 0 0 0 A7.9 0 0 0 0 0 0 0
2020-02-12 72 0 0 0 A7.9 0 0 0 0 0 0 0
2020-02-13 71 0 0 0 A7.8 0 0 0 0 0 0 0
2020-02-14 71 0 0 0 A7.7 0 0 0 0 0 0 0
2020-02-15 71 0 0 0 A7.7 0 0 0 0 0 0 0
2020-02-16 71 0 0 0 A7.7 0 0 0 0 0 0 0
2020-02-17 71 0 0 0 A7.6 0 0 0 0 0 0 0
2020-02-18 71 0 0 0 A7.7 0 0 0 0 0 0 0
2020-02-19 71 0 0 0 A8.0 0 0 0 0 0 0 0
2020-02-20 71 0 0 0 A8.1 0 0 0 0 0 0 0
Average/Total 72 4 14 1 0 0 0 2 0 0 0

Summary graph

Flares

Solar Wind

Solar Wind

The solar wind is a stream of plasma released from the upper atmosphere of the Sun. It consists of mostly electrons, protons and alpha particles with energies usually between 1.5 and 10 keV. The stream of particles varies in density, temperature, and speed over time and over solar longitude. These particles can escape the Sun's gravity because of their high energy, from the high temperature of the corona and magnetic, electrical and electromagnetic phenomena in it.

The solar wind is divided into two components, respectively termed the slow solar wind and the fast solar wind. The slow solar wind has a velocity of about 400 km/s, a temperature of 1.4–1.6×10e6 K and a composition that is a close match to the corona. By contrast, the fast solar wind has a typical velocity of 750 km/s, a temperature of 8×10e5 K and it nearly matches the composition of the Sun's photosphere. The slow solar wind is twice as dense and more variable in intensity than the fast solar wind. The slow wind also has a more complex structure, with turbulent regions and large-scale structures.

Solar radio flux at 10.7 cm

Solar radio flux at 10.7 cm

The solar radio flux at 10.7 cm (2800 MHz) is an excellent indicator of solar activity. Often called the F10.7 index, it is one of the longest running records of solar activity. The F10.7 radio emissions originates high in the chromosphere and low in the corona of the solar atmosphere. The F10.7 correlates well with the sunspot number as well as a number of UltraViolet (UV) and visible solar irradiance records. Reported in “solar flux units”, (s.f.u.), the F10.7 can vary from below 50 s.f.u., to above 300 s.f.u., over the course of a solar cycle.

Flares

Flares

A solar flare is a sudden flash of brightness observed over the Sun's surface or the solar limb, which is interpreted as a large energy release of up to 6 × 10e25 joules of energy. They are often, but not always, followed by a colossal coronal mass ejection. The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event.

Solar flares affect all layers of the solar atmosphere (photosphere, chromosphere, and corona), when the plasma medium is heated to tens of millions of kelvin, while the electrons, protons, and heavier ions are accelerated to near the speed of light. They produce radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays, although most of the energy is spread over frequencies outside the visual range and for this reason the majority of the flares are not visible to the naked eye and must be observed with special instruments. Flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. The same energy releases may produce coronal mass ejections (CME), although the relation between CMEs and flares is still not well established.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one every week when the Sun is "quiet", following the 11-year cycle (the solar cycle). Large flares are less frequent than smaller ones.

Classification

Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square metre, W/m2) of 100 to 800 picometre X-rays near Earth, as measured on the GOES spacecraft.

Classification Peak Flux Range at 100-800 picometer
W/m2
A < 10e-7
B 10e-7 to 10e-6
C 10e-6 to 10e-5
M 10e-5 to 10e-4
X 10e-4 to 10e-3
Z > 10e-3

An earlier flare classification is based on Hα spectral observations. The scheme uses both the intensity and emitting surface. The classification in intensity is qualitative, referring to the flares as: (f)aint, (n)ormal or (b)rilliant. The emitting surface is measured in terms of millionths of the hemisphere and is described below. (The total hemisphere area AH = 6.2 × 1012 km2.)

Classification Corrected area
(millionths of hemisphere)
S < 100
1 100 - 250
2 250 - 600
3 600 - 1200
4 > 1200

Sunspot number

Sunspots

Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They correspond to concentrations of magnetic field that inhibit convection and result in reduced surface temperature compared to the surrounding photosphere. Sunspots usually appear in pairs, with pair members of opposite magnetic polarity. The number of sunspots varies according to the approximately 11-year solar cycle.

Sunspot populations quickly rise and more slowly fall on an irregular cycle of 11 years, although significant variations in the number of sunspots attending the 11-year period are known over longer spans of time. For example, from 1900 to the 1960s, the solar maxima trend of sunspot count has been upward; from the 1960s to the present, it has diminished somewhat. Over the last decades the Sun has had a markedly high average level of sunspot activity; it was last similarly active over 8,000 years ago.

The number of sunspots correlates with the intensity of solar radiation over the period since 1979, when satellite measurements of absolute radiative flux became available. Since sunspots are darker than the surrounding photosphere it might be expected that more sunspots would lead to less solar radiation and a decreased solar constant. However, the surrounding margins of sunspots are brighter than the average, and so are hotter; overall, more sunspots increase the Sun's solar constant or brightness. The variation caused by the sunspot cycle to solar output is relatively small, on the order of 0.1% of the solar constant (a peak-to-trough range of 1.3 W/m2 compared to 1366 W/m2 for the average solar constant).

K-indices



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4 3 3 3 2 3 2



Data


Estimated Planetary

Estimated Planetary

Date A K-indices (UTC)
0h 3h 6h 9h 12h 15h 18h 21h
2020-01-23 5 2 3 1 0 0 0 1 1
2020-01-24 3 1 0 0 0 1 1 1 0
2020-01-25 3 0 2 1 0 1 0 1 0
2020-01-26 4 2 1 1 0 1 2 1 0
2020-01-27 3 1 1 1 0 0 0 0 0
2020-01-28 5 1 1 1 1 0 1 1 3
2020-01-29 9 3 3 2 2 1 1 2 2
2020-01-30 12 2 3 2 2 2 4 3 3
2020-01-31 8 3 4 2 2 1 1 1 1
2020-02-01 6 1 1 1 1 2 2 2 2
2020-02-02 6 2 1 1 1 0 1 3 2
2020-02-03 5 2 2 2 1 1 1 1 0
2020-02-04 5 3 2 1 1 1 1 0 2
2020-02-05 5 1 2 2 2 1 1 0 1
2020-02-06 15 1 2 4 3 3 2 4 3
2020-02-07 15 3 3 3 2 3 3 3 4
2020-02-08 6 3 2 1 1 2 2 2 1
2020-02-09 7 3 2 1 1 1 2 2 2
2020-02-10 5 2 1 2 2 1 1 1 2
2020-02-11 6 3 3 2 1 0 0 1 1
2020-02-12 4 2 2 1 2 1 0 0 1
2020-02-13 3 0 1 1 1 0 1 1 2
2020-02-14 3 2 1 0 0 0 0 0 1
2020-02-15 5 1 0 0 2 3 1 1 1
2020-02-16 3 2 1 0 1 1 0 1 0
2020-02-17 7 1 1 1 1 1 1 3 3
2020-02-18 14 1 3 4 2 3 3 3 3
2020-02-19 14 2 5 4 4 2 1 1 2
2020-02-20 8 2 3 2 1 2 1 2 3
2020-02-21 14 4 3 3 3 2 3 2

Middle Latitude

Date A K-indices
2020-01-23 3 2 3 0 0 0 1 0 0
2020-01-24 1 1 0 0 0 0 1 1 0
2020-01-25 3 0 2 0 0 2 1 1 1
2020-01-26 2 1 0 0 0 1 2 1 1
2020-01-27 2 0 1 1 0 1 1 0 0
2020-01-28 4 1 1 1 0 1 1 1 3
2020-01-29 6 2 2 2 2 1 1 1 2
2020-01-30 9 1 2 2 1 2 4 2 2
2020-01-31 6 2 3 1 2 1 1 1 1
2020-02-01 4 1 0 0 1 2 2 1 2
2020-02-02 4 1 1 1 0 1 1 2 2
2020-02-03 3 1 1 1 0 1 1 1 1
2020-02-04 5 3 2 1 1 1 1 0 2
2020-02-05 4 1 1 2 2 1 1 0 1
2020-02-06 13 1 2 4 2 2 2 4 3
2020-02-07 11 2 3 3 1 2 2 3 3
2020-02-08 4 2 1 1 1 1 2 1 1
2020-02-09 5 3 1 1 1 1 2 1 1
2020-02-10 4 1 1 2 1 1 1 1 2
2020-02-11 6 2 3 2 1 1 1 1 1
2020-02-12 4 2 2 1 1 1 0 1 1
2020-02-13 1 0 0 0 1 0 1 0 1
2020-02-14 3 2 2 0 0 0 1 0 1
2020-02-15 4 0 1 1 2 2 1 1 1
2020-02-16 2 2 0 0 1 1 1 1 0
2020-02-17 5 1 0 2 1 1 2 2 2
2020-02-18 11 0 2 4 2 3 2 3 2
2020-02-19 10 2 4 3 3 1 1 1 1
2020-02-20 5 2 2 2 0 1 1 2 2
2020-02-21 3 2 2 3 2 3 1

High Latitude

Date A K-indices
2020-01-23 2 1 1 0 2 0 0 0 0
2020-01-24 1 0 0 1 0 1 0 0 0
2020-01-25 1 0 1 0 1 0 0 0 0
2020-01-26 1 0 0 0 0 1 1 1 0
2020-01-27 0 0 0 0 0 0 0 0 0
2020-01-28 2 0 0 2 0 0 0 1 1
2020-01-29 9 2 2 3 4 1 1 1 1
2020-01-30 20 1 1 5 3 4 5 3 1
2020-01-31 12 2 4 2 5 2 0 0 0
2020-02-01 6 0 0 0 2 4 2 1 1
2020-02-02 2 1 0 0 0 0 1 2 1
2020-02-03 4 1 1 3 2 1 0 0 0
2020-02-04 4 0 0 1 3 2 2 0 1
2020-02-05 3 1 0 0 3 1 0 0 0
2020-02-06 20 0 1 5 4 5 2 3 3
2020-02-07 18 3 3 3 4 5 2 2 2
2020-02-08 7 3 1 1 1 3 2 1 1
2020-02-09 2 0 0 2 2 0 1 0 0
2020-02-10 7 1 0 3 4 1 0 1 1
2020-02-11 2 1 2 1 1 0 0 0 0
2020-02-12 5 0 0 1 4 2 0 0 0
2020-02-13 1 0 0 1 1 0 0 1 0
2020-02-14 0 0 0 0 0 0 0 0 0
2020-02-15 8 0 0 0 3 5 1 0 0
2020-02-16 1 1 0 0 1 0 0 0 0
2020-02-17 3 0 0 1 0 2 2 1 2
2020-02-18 36 0 3 4 5 6 6 4 2
2020-02-19 25 2 4 5 6 4 2 1 0
2020-02-20 11 1 3 1 4 3 3 2 1
2020-02-21 3 3 4 6 2 3 3

About

The K-index quantifies disturbances in the horizontal component of earth's magnetic field with an integer in the range 0–9 with 1 being calm and 5 or more indicating a geomagnetic storm. It is derived from the maximum fluctuations of horizontal components observed on a magnetometer during a three-hour interval. The label K comes from the German word Kennziffer meaning “characteristic digit”. The K-index was introduced by Julius Bartels in 1938.

The Estimated 3-hour Planetary Kp-index is derived at the NOAA Space Weather Prediction Center using data from the following ground-based magnetometers:

  • Sitka, Alaska
  • Meanook, Canada
  • Ottawa, Canada
  • Fredericksburg, Virginia
  • Hartland, UK
  • Wingst, Germany
  • Niemegk, Germany
  • Canberra, Australia

These data are made available thanks to the cooperative efforts between SWPC and data providers around the world, which currently includes the U.S. Geological Survey, Natural Resources Canada (NRCAN), the British Geological Survey, the German Research Centre for Geosciences (GFZ), and Geoscience Australia. Important magnetometer observations are also contributed by the Institut de Physique du Globe de Paris and the Korean Space Weather Center K-index Watches are issued when the highest predicted NOAA estimated Kp-indices for a day are K = 5, 6, 7, or >= 8 and is reported in terms of the NOAA G scale. K-index Warnings are issued when NOAA estimated Kp-indices of 4, 5, 6, and 7 or greater are expected. K-index Alerts are issued when the NOAA estimated Kp-indices reach 4, 5, 6, 7, 8, or 9.


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