This quantity is the propagation speed of gasdynamic (sound) waves in the solar wind. This quantity is the propagation speed of shear Alfven (intermediate mode) magnetohydrodynamic waves in the solar wind. The blue portion of the dial shows when magnetic processes govern solar wind structures the purple portion shows when thermal processes govern these structures. The base-10 logarithm of Beta is shown on the dial. This quantity is generally less important than either the solar wind ram pressure or the solar wind (IMF) magnetic pressure.īeta is the ratio between the thermal and magnetic energy densities in the solar wind this ratio controls whether particle thermal processes or magnetic processes dominate the behavior of the plasma. It takes into account both solar wind density and temperature and can be translated into solar wind thermal pressure. This quantity is the heat content of the solar wind. ( Journal of Geophysical Research 102, 111, 1997.) This estimate is asymptotic because it does not account for the time delays such as those imposed by friction between the ionosphere and the neutral atmosphere. The quantity shown here is an estimate of the asymptotic convection potential based on ACE/SWEPAM and ACE/MAG measurements as well as the work of Boyle, et al. It appears as an electric potential imposed across the polar ionosphere. This quantity measures the solar wind energy input to the magnetosphere that drives magnetospheric convection. Voltage Across the Polar Cap / Convection Potential: (Derived) This quantity also depends on IMF components measured by ACE/MAG. This affects the details of solar wind-magnetosphere interactions however, this is of tertiary importance compared to the IMF magnitude and polar angle. This quantity is the direction of the IMF perpendicular to the geomagnetic axis. Interplanetary Magnetic Field Azimuth: (Derived) This quantity depends on IMF components measured by ACE/MAG. Under less severe conditions this radiation can still threaten polar orbiting spacecraft. In severe conditions this radiation can threaten high altitude aircraft in high latitude and polar regions. This process can also open the magnetosphere to solar energetic particle radiation. This process increases the transport of solar wind mass, momentum, and energy into the Earth's magnetosphere. When the IMF is southward, antiparallel fields near the magnetospheric subsolar point allow merging between the IMF and geomagnetic fields. This quantity is the angle between the IMF and the geomagnetic axis.

Interplanetary Magnetic Field Polar Angle: (Derived) This quantity is the strength of the interplanetary magnetic field (IMF) as measured by the ACE Magnetometer (MAG).

Interplanetary Magnetic Field Magnitude: (Measured) This quantity is the temperature of protons in the solar wind. The solar wind ram pressure depends on the solar wind speed and density. This is similar in concept to the force a surface wind exerts on a sail. This quantity is the solar wind ram pressure, the force per unit area required to stop the solar wind flow. This is the solar wind speed just as the bulk speed of air molecules is the wind speed we know here on the surface of the Earth. This quantity is the average (bulk) speed of solar wind protons as measured by ACE/SWEPAM. This quantity is the number of solar wind protons per unit volume as measured by the ACE Solar Wind Electron Proton Alpha Monitor (SWEPAM). SPACE WEATHER : REAL TIME : INTERPRETATION GUIDE

Solar wind ram pressure