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Arrangement of Braunbek coils for compensation of the three components of the Earth's magnetic field

The Earth's magnetic field at PTB


Sensor hut
The Earth's magnetic field measurement hut at PTB
Geoposition: 52° 17.500' N 10° 27.948' E
Altitude above sea level: 83 m

At PTB's campus in Braunschweig the Earth's magnetic field is measured continuously. The data are required for the compensation of the Earth's magnetic field when sensitive measuring tasks are carried out.
In a magnetically undisturbed area in the woods at PTB's site, the Earth's magnetic field can be measured in a small wooden hut with special magnetometers.

Diagram of current data

In this diagram the Earth's magnetic field over the previous three days is shown with the current datapoint at the end. The Total Intensity as the Flux Density in nanotesla (nT) over time (CEST) is displayed. The diagram is updated as one measured value per minute.
To indicate information on single datapoints hover the cursor to the point of interest on the chart's line.


Current measurement 07.04.20 11:10 :
Total intensity: F = 49466.3 nT
Inclination: I = 67.02 °
Declination: D = 3.06 °

The values stated above are determined as vector quantities by a triaxial Fluxgate magnetometer: The Inclination I describes the angle of incline between the lines of magnetic flux and the Earth's surface plane. The Declination D is the angle between the magnetic and the geographic north direction.

In the course of one day, a typical result of the Total Intensity F measurement shows a distinct minimum at noon, when the sun reaches its daily peak. Seasonal variations and changes due to the weather or extraordinary solar activities* are superimposed on the parental magnetic field that is caused by geodynamo processes in the Earth's interior.

* Popup window: Animated view of the Sun over the past 48 hours  (Source: NASA) can take a moment to load

Local long-term changes

long term total intensity in nanotesla

Since the beginning of continuous registration of Earth's magnetic field data at the location of PTB in Braunschweig the positive trend of the Total Intensity in Europe can be observed. The above diagram shows the data of the Total Intensity in nanotesla as mean values per month. The rate of increase of nearly +28 nT/year could be measured also at the Geomagnetic Observatory in Niemegk. The angle of inclination changed by approx. +0,02°/year during the measurement period, the angle of declination by +0,17°/year.
However, globally the earth's magnetic field is decreasing. The increasing tendency in Europe is a local peculiarity, mainly caused by the increase of the sibirian-asian anomaly. The SWARM satellite project, that has collected data of the Earth's magnetic field worldwide, also can prove this trend in Europe.

Satellite data

Further, data of the current Earth's magnetic field are determined by magnetometers in the Earth's orbit. For example, magnetic field data by the geostationary GOES satellites are frequently published by NOAA (National Oceanic and Atmospheric Administration). These measurements are carried out uniaxially in northern direction, parallel to the Earth's axis ("Hp").

Source: NOAA

NOAA Scales mini

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Space Weather Conditions
24-Hour Observed Maximums
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Current Space Weather Conditions
R1 (Minor) Radio Blackout Impacts
HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals.
More about the NOAA Space Weather Scales

GOES Magnetometer

Since 1975, each of NOAA’s Geostationary Operational Environmental Satellites (GOES), located in Earth’s geographic equatorial plane, approximately 6.6 Earth radii from the center of Earth, have carried magnetometers to monitor the geomagnetic field and its variations. Typically there are two GOES operational satellites: GOES East, located over the east coast of the U.S. and GOES West, located over the Pacific, just west of the U.S. mainland. At times, though, data are available from more than the two prime operational satellites.

The geomagnetic field measurements are important for interpreting GOES energetic particle measurements and for providing alerts to many customers, specifically for indicating the onset of a geomagnetic storm (known as a sudden storm commencement). GOES magnetometer data have been used for constructing magnetic field models, and to help forecasters identify the buildup and release of energy in Earth’s magnetosphere that occurs during geomagnetic storms and substorms. The magnetic field measurements can also indicate when the solar wind has pushed the boundary of the magnetosphere, the magnetopause, inside of geosynchronous orbit. Those situations are usually during very disturbed space weather conditions and can be important for spacecraft operations.

GOES Magnetometer data are also important in research, being among the most widely used spacecraft data by the national and international solar and space weather research community (see e.g. NASA CDAWeb usage statistics). The data have often been used to support launch decisions for research sounding rockets. The measurements can also be used to validate large-scale space environment models of the coupled magnetosphere and ionosphere; SWPC will implement such a model in the near the future.

The GOES magnetometer products are an integral part of the National Oceanic and Atmospheric Administration (NOAA) space weather operations, providing information on the general level of geomagnetic activity and permitting detection of magnetic storms and substorms. In addition, these measurements will be used to validate large-scale space environment models that will be added to SWPC operations in the future.

Historically, the data have been presented in the E (earthward), P (parallel) and N (normal) coordinate system where:

Hp: magnetic field vector component, points northward, perpendicular to the orbit plane which for a zero degree inclination orbit is parallel to Earth's spin axis.

He: magnetic field vector component, perpendicular to Hp and Hn and points earthward.

Hn: magnetic field vector component, perpendicular to Hp and He and points eastward.

Ht: the total field.

The GOES 3-day Hp plot shows the 1-minute averaged parallel component of the magnetic field in nanoTeslas (nT), currently measured at GOES-13 (~75 degrees west geographic longitude) and GOES-15 (~135 degrees west geographic longitude). The longitudes can vary, so for any particular case it is important to check the satellite location. A diurnal variation is observed in these data as a result of magnetospheric currents systems that, at geosynchronous orbit, produce a stronger magnetic field on the dayside of Earth and weaker magnetic fields on the nightside. If these data drop to near zero, or less, when the satellite is on the dayside, it may be due to a compression of the Earth's magnetopause into the geosynchronous orbit boundaries, exposing satellites to negative and/or highly variable magnetic fields. On the nightside, the smaller field values indicate strong currents in the magnetotail that are often associated with the stretching and subsequent release of energy in Earths tail. This is one signature of a “substorm” that results in aurora at Earth’s high latitudes and energetic particle injections in the vicinity of geosynchronous orbit.

Noon and midnight local time at the satellite are plotted as N and M. Default scaling is 0 to 200 nanoTesla. Non-default scaling to include infrequent extreme values is labeled in red to emphasize the change in scale.

This page updates dynamically every 5 minutes

GOES magnetic field observations have been made since the first GOES satellite was launched in 1975, and prior to that they were made on the NASA Synchronous Meteorological Satellites (SMS 1 and 2). SMS were the forerunners to the GOES operational system.

The magnetometers on GOES have changed, from one block of satellites to the next. In more recent years, NOAA has operated the GOES 8 to 12 series (from about 1994 to 2011 for the magnetometers), and currently we are using the GOES 13, 14, and 15 series of satellites. Each GOES 8-12 satellite was three-axis stabilized and carried two fluxgate magnetometers on a three-meter boom. Only one magnetometer could be operated at a time. The highest resolution magnetic field data was 0.512 s. On the GOES 13, 14 and 15 series, there are two fluxgate magnetometers that can be operated simultaneously on an 8.5 m boom. Again, the highest resolution is 0.512 s.

The dynamic plot above can be downloaded in multiple image formats using the menu at the upper right. The menu also offers the ability to download the displayed numerical data in JSON format.

Numerical data are also available directly from SWPC's data service at: 


In that directory the file instrument-sources.json provides the mapping of primary and secondary measurements from each instrument to the satellite from which that measurement is made. The file satellite-longitudes.json provides the longitudes of the satellites. Observation data are found under the primary and secondary subdirectories.

NOTE: After January 31, 2020 other JSON/GOES data files and subdirectories will be removed. This is due to discontinuation of GOES-14 and GOES-15 observations on that date.

Historical 3-day plots and text files from 1996 through January 2020 are available at: 


or by following the archive link under “Data Access." Daily forecast reports are also available beginning in 1966.

The official archive for GOES data, can be found at:



For convenience and for correlative science with NASA satellite and related data, many years of GOES magnetometer 1-min and some high-resolution (0.5 s) data can be found at NASA Coordinated Data Analysis Web: http://cdaweb.gsfc.nasa.gov/

A description of the GOES 8-12 Magnetometer data can be found at:

Singer, H.J., L. Matheson, R. Grubb, A. Newman and S.D. Bouwer, Monitoring Space Weather with the GOES Magnetometers. SPIE Conference Proceedings, Vol. 2812, p. 299-308, GOES-8 and Beyond, Edward R. Washwell, ed., 1996.

Additional information can be found at the National Centers for Environmental Information (NCEI). http://www.ngdc.noaa.gov/stp/satellite/goes/


Current status information

Earth's Magnetic Field (Kp index)

The three hour planetary Kp index reflects the fraction of the measured Earth’s magnetic field that is caused by solar particles. It is shown for the present day and the current week. This index was introduced in 1949 by Julius Bartels. It is defined as measure of the geomagnetic effects by solar particle streams and is derived from Earth's magnetic field data of the most disturbed horizontal components. Taking values of 0 to 9 on a quasi-logarithmic scale it is published as average of local measurements of 13 magnetic observatories worldwide.
New data in the diagram will appear 45 minutes past the end of the current three hour period.

Status of Earth's magnetic field

Source: Helmholtz-Centre Potsdam GFZ German Research Centre for GeoSciences

Solar Activity

The Sun's Radiant Flux Density E, also referred to as Irradiance, given in electromagnetic energy per area, is observed and measured by GOES satellites. A solar storm also influences the measured Earth's magnetic field to a high degree. A high energy particle stream caused by solar flares reaches the Earth within a time interval of 1 to 3 days (see Kp-Index).
In the following diagram the Radiant Flux Density E (Source: GOES satellites) in the spectral X-ray range of 0.05 to 0.4 and 0.1 to 0.8 nanometer (nm) wavelength of the recent three days is displayed. Values of higher than 10 µW/m² should provide an indication of solar coronal mass ejections. A normal or quiet solar activity is indicated by values below 1 µW/m².
The data are updated as one measured value per minute. More real-time solar activity data are frequently published by SpaceWeatherLive.


Quelle: NOAA



Physikalisch-Technische Bundesanstalt
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