HR: 0830h
AN: SM51B-0515    [PDF]
TI: Solar Wind Amplification and Distribution Invariance of Short Time--Scale Geomagnetic Variability in the Auroral Zone
AU: * Weigel, R S
EM: Robert.Weigel@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Baker, D N
EM: Dan.Baker@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303 United States
AB: Using a 22--year data set of one--minute magnetometer measurements at an auroral--zone location, a statistical model of short time--scale geomagnetic fluctuations is developed and used to evaluate how geomagnetic dynamics are influenced by different solar wind controlling parameters. The functional form of the probability distribution function (PDF) that describes extreme--value minute--to--minute (greater than 2$\sigma$) changes in the ground magnetic field ($\Delta x$) in the auroral zone is shown to be independent of solar wind (SW) forcing and nearly independent of the local time and day of year (DOY) variables. Instead of modifying the intrinsic dynamics, as characterized by the functional form of the PDF of $\Delta x$, these variables are shown either to amplify or reduce the absolute level of variability of the fluctuations: the primary difference in the PDF of $\Delta x$ during weak and strong solar wind forcing is its standard deviation; the functional form of the PDF = $f\left[\Delta x/\sigma(\mbox{\small DOY,LT,SW})\right]$ is nearly invariant. In a statistical interpretation, we conclude that differences in solar--generated conductivity, seasonal effects, strength of solar wind forcing and variability, and position of the magnetometer ground station in local time do not change the structure of the dynamics, as characterized by the probability distribution of $\Delta x$, but rather serve to amplify the intrinsic dynamics.
DE: 3299 General or miscellaneous
DE: 7819 Experimental and mathematical techniques
DE: 7863 Turbulence
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting