NASA - National Aeronautics and Space Administration

+ Multimedia Image Captions

Image 1 (Giles): Large-scale disturbances in the ionosphere start with disturbances on the Sun. Solar flares and coronal mass ejections (CMEs), and the associated giant clouds of plasma that travel through space, are the largest explosions in the solar system. When such CMEs are directed toward the earth, turbulent shock waves of charged gas and their accompanying magnetic fields impact our Earth's protective layer, called the magnetosphere. These impacts in turn cause storms within our magnetosphere that impact our ionosphere and interfere with radio, television, and telephone signals, damage satellites and disrupt GPS communications. Credit: NASA

Images 2, 3 (Goldstein): The near-Earth space environment is not a perfect vacuum, but is filled with plasma formed when the sun's ultraviolet rays electrify the upper parts of the Earth's atmosphere. We know what the plasmasphere looks like by taking images of it from satellites positioned far above the Earth. The right panel shows a model plasmasphere based on the satellite image data shown in the left panel. Cameras onboard the NASA IMAGE satellite capture the ultraviolet glow emitted by the plasmasphere, producing the false-color picture to the left. The plasmasphere is the green-to-white region surrounding the Earth. The viewpoint of the animation varies from above the North pole to below the South pole of the Earth, and shows the 3-D shape of the plasmasphere. The plasmasphere is the green doughnut-shaped region that mostly follows the Earth's gray-colored magnetic field lines. Credit: NASA

Image 4 (Goldstein): "Before" and "After" snapshots of Plasmaspheric erosion caused by the April 11 space storm, obtained by the NASA IMAGE satellite which monitors the global effects of space weather. Shown to the left is the plasmasphere before the storm. Initially, it was large, with a diameter 6 to 10 times that of the Earth. To the right is the plasmasphere after the storm. The space storm eroded away the outer layers of the plasmasphere, making it about 30 percent smaller. Best estimates are that the storm stripped mass from the plasmasphere at a rate of about 36 metric tons per hour. A prominent signature of the erosion is the plasmaspheric plume, the thin "strand" of material that stretches sunward from the plasmasphere in the image. Credit: NASA

Image 5 (Goldstein): "Before" and "after" illustrations of plasmaspheric erosion caused by the April 11 space storm. When a space storm hits the plasmasphere, it strips away the outer layers, forming a huge plume of eroded plasma that stretches sunward. These images show a side view of the Earth with the Earth's magnetic field represented by the curved gray lines. The green regions show a side view (that is, a cross section) of the doughnut-shaped plasmasphere. The effect of a space storm is to pull the plasma sunward on the dayside of the Earth. As a large volume of plasma is pulled sunward, it maintains its doughnut shape, following the magnetic field line geometry. Because of the magnetic geometry, as the plasma is dragged sunward, the footpoint of the plasma, at lower altitudes in the ionosphere, is dragged to higher latitudes. Credit: Jerry Goldstein/SwRI

Image 6 (Goldstein): Illustration of how plasmaspheric plumes map magnetically to ionospheric plasma moving to higher latitudes. This 3D cutaway view shows the image of the plume in green, with the Sun to the left. Three magnetic field lines that cross the plume and led to the ionosphere are drawn. When scientists traced along these field lines, down to the ionosphere, they found an ionospheric signature of the plume. Credit: Jerry Goldstein/SwRI

Images 7, 8 (Coster): Shown are two maps of Total Electron Content (TEC) that, in this case, show dramatic density features developing over the continental US on April 11, 2001, before (figure to the right) and during a large geomagnetic storm (figure to the left). The TEC is a measure of the total number of electrons in a vertical column that extends all the way up from the ground through the ionosphere; enhancements in TEC mean increased effects on radio wave propagation. TEC is measured by ground station receivers distributed across the globe that continually listen for signals from GPS satellites. Because the ionosphere is refractive, changes in the TEC change the speed of the GPS signals. Higher than normal TEC values, or TEC enhancements, are indicated in the orange and red regions of the figures. A TEC plume is shown in the figure to the right as the narrow red feature of enhanced ionospheric plasma that can be seen moving up from the Northeast US and over into Canada. An example space weather storm TEC map is shown here, where you can see dramatic features in the TEC that, in this case, developed over the continental US. Credit: NASA/NSF/MIT

Image 9 (Coster): This second plasma cold front event is from November 20, 2003, which was one of the largest solar storms of the last solar cycle. In this movie you can clearly see the plume developing and the density enhancements in the plume moving up into Canada and flowing back over the pole to Europe. The sharp pole-ward edge of the plume is produced by storm-induced electric fields, which originally develop in the magnetosphere and penetrate far into the ionosphere. Credit: NASA/NSF/MIT

Image 10 (Coster): Evidence that the ionospheric plumes follow a repeatable pattern and may be predictable. The latitude where the plume forms is consistent as a function of time for three different storm days over two different years. Credit: Marlene Colerico/Anthea Coster, NSF/MIT

Image 11 (Mannucci): The sequence shows how plasmaspheric plumes map to the ionospheric plumes. The 3-D view starts by showing the image of the plasmasphere in green, with the sun to the left. Magnetic field lines cross the plume and lead to the ionosphere (light gray). When scientists traced these field lines down to the ionosphere, they found a high-density ionospheric signature of the plume. By comparing the space-based and ground-based features, scientists saw the interconnectedness in the ionosphere and plasmasphere. The space-based and ground-up views allowed us to build a picture of how different regions of the atmosphere respond as a coupled system. As our understanding grows, we are better able to predict space weather impacts on operational users and lessen their impact on technology. Credit: NASA/NSF/MIT

Add. Image 12: Rapid changes in GPS ranging errors occurred as U.S. cities moved under the ionospheric plume during the major space storm of Nov. 20, 2003. The two traces are the range error for two different eastern US receivers and a GPS satellite. In about four minutes, the ranging signal changed by about 20-30 meters (60-90 feet) at Philadelphia. This sudden range change causes an error in the calculation of the user's position, which could reach as high as three times the range error, or 90 meters (270 feet or 90 yards!). That is a serious error for civilian users of GPS that rely on GPS to locate them down to the block and street level. NASA and NSF-supported research will enable predictions of when and how these errors appear, making the use of GPS technology reliable even during these storms. Image Credit NSF/MIT/SWRI

Add. Image 13: Illustration of how the ionosphere and impinging plasma plume can disrupt signals to GPS users. Users fix their location by triangulating on ranging signals transmitted from four GPS satellites whose locations are known precisely as they orbit the Earth. Space weather cold fronts impose large errors on the GPS signals, that can vary quite a bit over just a few minutes, throwing the user's position off when they least expect it. Credit: NASA/SwRI