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The DREAM Project




Description of the Plots

The DREAM beta web service contains two basic plot types: flux and phase space density. Each plot type is selectable using the tabs above the plot.

In either mode, flux or phase space density (PSD) is plotted (using a color-coded scale) as a function of time and radial distance (R) or Drift Shell (L*), both in units of Earth Radii (1 Re = 6370 km). Plots cover approximately 1 month. The plots update automatically every time new data are assimilated. New GOES data is available approximately every 5 min. Status bars at the top of the plot show the status of data availability and progress of the assimilation. It is possible for new data to show up for an earlier time It is also possible for ancillary data such as Kp or calculations of the magnetic invariants to be updated for some time in the past. Progress of recalculating data values is shown in the Data Status bar. Whenever the primary or ancillary data change new assimilations from that time to the present must be calculated and that progress is indicated in the Assimilation Status bar.

When flux (j) is displayed it is in units of particles/(cm2-s-sr-MeV)-1. Six different energies ranging from 1 MeV to 6 MeV are selectable using the pull-down menu below the plot. Five different equatorial pitch angles values ranging from 55° to 75° are also selectable. Each selected energy and pitch angle range returns flux values for a different range of radial distances (R) for reasons described in the procedures and artifacts sections.

When phase space density is displayed it is in units of (c/cm-MeV)3 for fixed values of the adiabatic invariants, µ, and K. Five different values of µ ranging from 1,000 to 20,000 MeV/G and five different values of K ranging from 0.0125 to 0.20 G½ RE are selectable using the pull-down menus. For PSD, DREAM returns valid (but not necessarily accurate) values for all L* from 1 to 10 in 0.1 RE bins.

Selected space weather parameters such as Kp and Dst are shown in tabular or plot form below the DREAM results. Which parameters are shown may change as we continue to develop the DREAM web service. Similarly the links to the left or right of the plot and the content that those links point to may also vary. Screen shots as of May, 2010 are shown below.

Figure 1:Final DREAM output is flux as a function of equatorial altitude (R) and time. Fluxes for 3 MeV and 65° equatorial pitch angle are shown here but are selectable with the pull down menus just below the plot.

Figure 2:The actual assimilation in DREAM uses phase space density at fixed magnetic invariants (µ, K, L*). Assimilations are done for 25 different µ-K pairs and are visible in the Phase Space Density tab.

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