Hourly STD DMSP/POLAR Auroral Activity Report
Hourly STD DMSP/POLAR Auroral Activity Report
(Auto-updated every 5 minutes)
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The image above is the most recent VIS image of the northern polar auroral oval, taken by the POLAR spacecraft.
The image above is the most recent ultraviolet image of the northern polar auroral oval, taken by the POLAR spacecraft. Lines of latitude and longitude are denoted by the dashed blue lines. Contintental outlines are also shown in green.
The image above is the most recent estimated shape and character of the northern polar auroral oval, as derived from recent measurements of energy deposition into the auroral oval by the NOAA/TIROS spacecraft and as statistically derived and provided courtesy of the Space Environment Center. The color bar at the right denotes the estimated power flux input into the auroral zone, in ergscm^-2sec^-1. The yellow arrow points in the direction of the noon sector, where sunlight would prevent observations of auroral activity.
The image above is the most recent estimated shape and character of the southern polar auroral oval, as derived from recent measurements of energy deposition into the auroral oval by the NOAA/TIROS spacecraft and as statistically derived and provided courtesy of the Space Environment Center. The color bar at the right denotes the estimated power flux input into the auroral zone, in ergscm^-2sec^-1. The yellow arrow points in the direction of the noon sector, where sunlight would prevent observations of auroral activity.
This new plot estimates the VISIBILITY of auroral activity from any location in the northern hemisphere, assuming a dark moonless sky and low light pollution. It is updated every 5 minutes with the latest solar wind data. The model computes the estimated brightness of auroral activity and plots this on the map as a solid bright color that varies from green (NIL to low levels of auroral activity) to brown/orange (low to moderate levels of activity) to red (moderate to high levels of activity). The brighter the red, the more intense the activity. Those areas which may be able to spot activity are most often within the zone of fading color on the outskirts of the plotted auroral oval. The extent of the fading color zone on the outskirts of the oval is based on the estimated height and intensity of auroral luminosity.
Use this chart to quickly determine whether auroral activity might be visible from your location and what intensity the activity might be. The image is created using a model that computes the potential auroral luminosity from current solar wind conditions. It has been verified for accuracy using historic POLAR spacecraft data. Although the model works very well and should provide visual observers with a good estimate of the visibility of auroral activity, it is not perfect and may occasionally under or overestimate the visibility of activity from some regions. This is due to the unpredictable nature of auroral substorm activity.
The following plot shows the current position of the auroral oval as determined by the polar orbiting Defense Meteorological Satellite Program (DMSP) satellites. The green oval defines the approximate shape of the diffuse auroral oval as determined by the electron precipitation sensors on-board the DMSP spacecraft.
The approximate location of the solar terminator at an altitude of 110 km (the height at which the lower-altitude auroral lumination occurs) is shown by the gray line. The terminator line (gray line) as well as the auroral oval position (green line) are valid at the times indicated.
Ground-based sightings of auroral activity are also provided on this map and are valid at the times given at the top-right of the plot below. All stations reporting activity during the current UTC day are plotted as white dots.
The USAF updates the DMSP oval data and the grayline whenever the space shuttle is in orbit or when the geomagnetic A-Index reaches or exceeds 20. The ground-based sightings are updated every hour. Consult the STD near-real-time map of the auroral zone for more recent indications of the location of the auroral ovals.
The auroral oval boundaries and the solar terminator lines appear jagged because they are taken directly from textual reports issued by the United States Air Force Global Weather Central who continually receive and process the DMSP data. In other words, the textual reports are converted to graphical maps and some resolution is lost in the process. However, the plotted locations are accurate. The jagged edges should be visually smoothed.
The auroral oval line represents the equatorward boundary of the diffuse auroral oval and is therefore useful for radio communicators and others to determine precise auroral oval locations. Signal degradation can be expected if signal paths cross through the indicated equatorward boundary.
Those who are interested in visibly observing auroral activity should closely watch the equatorward boundary. This boundary may not always be discernable with the naked eye. Most of the more luminous activity tends to occur a bit poleward of the equatorward edge.
The Effective Q Index is similar to the geomagnetic K index. It is a quasi-logarithmic value and is based on geomagnetic data from several high latitude (auroral-zone) magnetic observatories. It is also adjusted so that the plotted auroral oval coincides with the DMSP data collected during polar passes through the auroral zones.
These maps are produced using both northern and southern hemisphere polar passes, but are only valid for the northern hemisphere. Locations where the DMSP satellites cross into the auroral zones are marked on the maps with a cyan colored 'X'. For southern hemisphere passes, the location where the satellite crosses the southern auroral zone is converted into the northern-hemisphere conjugate point and this point is plotted. The location of magnetic midnight is identifed with a red colored 'X'.
The auroral oval and solar terminator lines are updated more frequently during periods of stronger activity. The ground-based sightings are updated hourly.
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