Geophysical Help Page

By clicking on the links you will find explanations of the data and information presented in the Geophysical Section. For general terms and definitions please refer to our Glossary of Solar Terrestrial Terms.

Note: The indices and icons below are SAMPLES ONLY.

Magnetograms

Clicking on this link displays a list of stations for which near real-time magnetograms (time series plots of magnetometer measurements of the variation of the Earth's magnetic field) are available. Selecting a station will display the most recent magnetogram, along with limited information about the recorded magnetometer data used to produce these plots.

Magnetometer Measurements - Components of the Earth's Magnetic Field

A magnetogram is a time series measurement of the principal components of the Earth's magnetic field as measured on the ground. The components of the geomagnetic field are as follows: h corresponds to geomagnetic north (ie. is in the direction of the mean geomagnetic field parallel to the earth's surface); d corresponds to geomagnetic east or the component perpendicular to h and tangent to the surface; z is the vertical component normal to the surface with down usually positive. An alternate set of components, especially at high latitudes is x,y and z where x and y correspond to geographic north and east respectively and z is again the vertical component. Generally in magnetograms the "secular" or averaged long term values of the components of the geomagnetic field are subtracted from the measured values so as to pick up just the short time scale variations from the mean. The variations in magnetic field components are around 100 nT while the absolute values of the components are around 50,000 nT.

Indices

Clicking on this link displays a list of index type for which near real-time index plots are available: K-index, Pulsation Index, A-index, AusDst-index, and GIC-index. Clicking on K-index Plots displays a pull-down menu of available stations. Selecting a station from the menu list displays the most recent K-index plot. Clicking on Pulsation Index Plots displays a series of checkboxes which can be used to select the type of pulsation index plot to be displayed, with the plot types grouped into time series or recurrence plots. Following the button menu system displays a pull-down menu list of stations for which near real-time plots of the selected index are available. Selecting a station will display the most recent pulsation index plot. Clicking on A-index Plots displays a time series plot of the last 28 days of planetary A-index. Clicking on AusDst-index Plots displays a time series plot of the last 24 hours of the Australian region Dst-index. Clicking on GIC-index Plots displays a near real-time map of GIC-index.

Maps

Clicking on this link displays links to the most recent colour contour maps of K-index data from the Australian region and pc3-index data from the Australian region.

Cosmic Ray

Cosmic rays consist mainly of protons. They can originate from galactic cosmic radiation or from the Sun. Cosmic rays are observed indirectly by a device known as a neutron monitor. When cosmic ray particles enter the Earth's atmosphere they interact with the nuclei of the air molecules to produce secondary radiation. The neutrons predominate in this secondary radiation and the cosmic ray detector actually detects the secondary neutrons.

The magnetic fields entrapped in and around coronal mass ejections exert a shielding effect on the galactic cosmic radiation that is detected by the neutron monitors. This causes a reduction in the count rate from the monitor, typically from about 3 to 20%. This reduction is a reliable indicator of a geomagnetic storm with warning times of up to 24 hours or more.

Geomagnetic Warning

Clicking on this link will display the latest geomagnetic warning information. When a warning of expected increased levels of geomagnetic activity is current the green "No Warning"icon will change to the red "Warning" Icon.

Geomagnetic Alert

Clicking on this link will display the latest geomagnetic alert information. When alert levels have been reached the green "No Alert" icon will change to the red "Alert" icon. Geomagnetic alerts are issued whenever the Australian region estimated K-index reaches 5 or greater.

GEOSTAT Alert

Clicking on this link will display the latest GEOSTAT alert information. The GEOSTAT (GEOmagnetic STorm Alert Tracking) system has been developed to monitor the progress of a geomagnetic storm from its origin on the sun (Level5), to its impact on the Earth's magnetic field and subsequent geomagnetic storm (Level 0). The alert sequence is from 5 down to 0 to simulate a "countdown" style to the alert levels. When alert levels have been reached the green "No Alert" icon will change to one of the six GEOSTAT alert level icons. If GEOSTAT alert level 0 has not occurred within four days of GEOSTAT alert level 5 being issued, the GEOSTAT icon changes to the "Alert Fail" icon and a message indicating the geomagnetic storm failed to eventuate is issued.

Aurora Alert

Clicking on this link will display the latest aurora alert information. When alert levels have been reached the green "No Alert" icon will change to the red "Alert" icon. Aurora alerts are issued whenever the Australian region estimated K-index reaches 6 or greater. When an alert is current the alert information indicates the latitudinal range in terms of high, middle, low and equatorial regions where aurora may be visible under good observing conditions. There is also a link to reports of aurora sightings observed during previous alert conditions.

Daily Report

Clicking on this link displays the Daily Report which provides a summary of geomagnetic conditions observed over the previous 24 hours of the UT day and a forecast of conditions likely for the next 3 days. Conditions are described in terms of the following levels (in increasing order of geomagnetic activity):

• Quiet
• Unsettled
• Active
• Minor Storm
• Major storm
• Severe storm

The observed geomagnetic activity is also described in terms of an estimated K-index and A-index. Observed geomagnetic activity is also described in terms of Daily pc3 Indices. The estimated A-index (planetary and for Fredricksburg, USA) for the current UT day and the observed A-index (planetary and for Fredricksburg, USA) for the previous UT day are also given. The final section of this report is a three day forecast in terms of A-index (planetary) and the geomagnetic activity levels explained above. A "COMMENT" section is often present which provides more detail on the current space weather environment likely to effect the geomagnetic field.

Weekly Report

Clicking on this link displays the SWS Weekly Geophysical Report which provides a summary of geomagnetic conditions observed over the previous week and a forecast for the next month. The observed conditions are given in terms of K-index and A-index values generated from data from the Australian region. The observed conditions are also given in terms of a text summary which notes any significant disturbances experienced during the week. The final section of the report is a forecast of disturbances expected for the coming month.

Auroral Oval

Clicking on this link displays an interactive map which can be used to calculate an estimate of the extent of the northern and southern hemisphere auroral ovals. One of the input parameters to the model is the Australian region estimated K-index. The default value is the latest Australian region estimated K-index. The map also allows the user to select other K-index values. The map displays the location of aurora sightings from the SWS archive, including descriptions and photographs of the aurora if available.

Magnetograms

Clicking on this link displays a list of stations for which historical magnetograms (time series plots of magnetometer measurements of the variation of the Earth's magnetic field) are available. Clicking on a station will display a listing of image filenames of previous magnetograms in a new window, with the filename containing the date information. Clicking on an image filename will display the magnetogram for that day.

Indices

Clicking on this link displays a list of the different types of index plots for which historical plots are available. Clicking on an index type will display a pull-down menu list of stations for which historical index plots of that type are available. Selecting a station will display a listing of image filenames of previous index plots in a new window, with the filename containing the date information. Clicking on an image filename will display the index plot for that index type for that station for that day.

Magnetometer Data Files

Clicking on this icon displays a list of stations for which historical magnetometer data files are available. Clicking on a station will provide a listing of the historical data files available in a new window, with the filename containing date information. A file named "README" provides information on the type of compression used. Files with the extension "new" are uncompressed and contain the most recent hour of data for that day. These "new" files are usually only kept for several days, while the compressed or "zip" files are normaly kept for 28 days.

The data files contain a one line header which contains the station code, the latitude and longitude of the station, the geomagnetic field components in the file, the sample frequency, the resolution in (nT/LSB), a data type identifier, and the format statement of the following data in the file. Each line of data has the hour, minute, second, followed by the field component data in the order given in the header.

Geophysical Links

Clicking on Geophysical Links displays a list of organisations related to Geophysical and Space-weather research and monitoring.

Geophysical Help Page

The Geophysical Help Page gives a short explanation of the data and information provided under each sub-section of the Geophysical Section.

Latest News

Latest News consists of recent SWS news items of particular relevance to the Geophysical community. News items include predictions and reports of significant space weather occurences and udpates or additions to the SWS website and services.

Australian Region Estimated K-Index and Map

Clicking on this link gives the most recent estimated K-index value and map generated from data from all available Australian stations. The value displayed by the icon gives the most recent estimated K-index averaged for the Australian region. The full range of K-index icons are shown below. The regional contour map is produced by contouring the estimated K-indices generated from the available station data at the universal time indicated. The "No Data" icon indicates that data for the previous hour was unavailable.

Australian Region pc3 Index and Map

Clicking on this link gives the most recent maximum pc3 pulsation index generated from the most recent magnetometer data from all available stations. The full range of Pc3-index icons are shown below. The regional contour map is produced by contouring the pulsation indices generated from the available station data for the universal time indicated. The "No Data" icon indicates that data for the previous hour was unavailable.

For more information on geomagnetic pulsations and their effects on geomagnetic surveys please see the Educational section.

Australian Region Dst-Index

Clicking on this link gives the most recent Australian Region Dst-index value, averaged for low-mid latitude stations in the Australian region. The full range of Dst-index icons are shown below. The "No Data" icon indicates that data for the previous hour was unavailable.

Australian Region GIC-Index

Clicking on this link gives a map of the Australian Region showing contoured GIC-index amplitudes, in addition to a vector indicating the direction of this field which scales with field amplitude. For low levels of GIC-index activity the vectors appear as dots and increase in size to be visible as directional arrows when activity increases.

K-Index

The estimated K-index for each station is derived from the H component (or D component) of the geo-magnetic field. After subtracting the local quiet background variation for a given location, the range of the variation in H (or D) over the 3-hour interval determines K. Whichever component, H or D, gives the largest variation in nT (nano Tesla), is assigned a value from 0 to 9 using a predetermined semi-logarithmic scale. Estimated K-indices generated for the Australian region are the average of the estimated K-indices from the individual stations and have a range of values 0 to 9.

Pc3 Index

Geomagnetic pulsations are variations of the Earth's magnetic field which are classified by their structure and frequency. Pc3 pulsations are variations in the Earths magnetic field with periods of 10 to 45 seconds (22 to 100 mHz). The Pc3 pulsation indices are generated from 20 minute intervals of data filtered over the Pc3 pulsation bandwidth, and are calculated from the rms value (in nanoTesla) multiplied by a scale factor of 10. Index values are integer values 0 or greater. Indices derived from the 2 horizontal components are referred to as "pc3" indices, while those generated using 3 component data, where available, are referred to as "Pc3" indices. Daily pulsation indices are derived from the individual pulsation indices by summing the index values greater than 1 for local daytime hours.

A-Index

The A-index is an arithmetic mean of the eight daily a-index values where the a-index is the latitude adjusted amplitude equivalent (in nanoTesla) of the estimated K-index value. Indices with the subscript "p" usually indicate "planetary" index values, which have been generated using a standard set of observatories from around the world.

Dst-Index

The Dst-index was derived to quantify the decrease in the geomagnetic field H-component observed during the main phase of magnetic storms produced mainly by the equatorial current system in the magnetosphere referred to as the ring current. An Australian region Dst-index, AusDst, is produced by averaging individual station Dst values from low-mid latitude stations in Australia. The Dst-index values are mapped to the following colours: green for "No Storm: Dst > -20 nT", yellow for "Weak Storm: Dst < -20 nT", orange for "Moderate Storm: Dst < -50 nT", red for "Strong Storm: Dst < -100 nT", and dark red for "Severe Storm: Dst < -200 nT".

GIC-Index

Geomagnetically Induced Currents (GICs) flow in long grounded conductors such as power grids and pipelines as a result of potential differences established by the "geoelectric" field and the associated time varying "geomagnetic" field. The maps are contoured "GIC-index" which is a proxy for the "geoelectric" field in addition to a vector indicating the direction of this field which scales with field amplitude. GIC-index values are mapped to the following colours: green for "No Risk: GIC < 50", yellow for "Low Risk: GIC > 50", orange for "Moderate Risk: GIC > 125", red for "High Risk: GIC > 300", dark red for "Extreme Risk: GIC > 600".

Recurrence Plots

Recurrence plots show stack plots of "daily" pulsation indices. Each of the stack plots show index data for one solar rotation period, 27 days, from which recurrent patterns of activity maybe determined. Days where daily index values were unavailable are indicated by red squares. Days where the daily index has not been fully determined (ie., the number of individual indices required for the full day were unavailable) are indicated by a yellow triangle. An orange star is used to indicate automated forecast daily indices.

Warning Icons

Alert Icons

GEOSTAT Icons

K-Index Icons

Pc3-Index Icons

Dst-Index Icons

Other Icons