Magnetic field power spectra and magnetic radial diffusion coefficients using CRRES magnetometer data

<jats:title>Abstract</jats:title><jats:p>We used the fluxgate magnetometer data from Combined Release and Radiation Effects Satellite (CRRES) to estimate the power spectral density (PSD) of the compressional component of the geomagnetic field in the ∼1 mHz to ∼8 mHz range. We conclude that magnetic wave power is generally higher in the noon sector for quiet times with no significant difference between the dawn, dusk, and the midnight sectors. However, during high <jats:italic>K</jats:italic><jats:italic>p</jats:italic> activity, the noon sector is not necessarily dominant anymore. The magnetic PSDs have a very distinct dependence on <jats:italic>K</jats:italic><jats:italic>p</jats:italic>. In addition, the PSDs appear to have a weak dependence on McIlwain parameter <jats:italic>L</jats:italic> with power slightly increasing as <jats:italic>L</jats:italic> increases. The magnetic wave PSDs are used along with the Fei et al. (2006) formulation to compute <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/jgra51576-math-0001.png" xlink:title="urn:x-wiley:jgra:media:jgra51576:jgra51576-math-0001"/> as a function of <jats:italic>L</jats:italic> and <jats:italic>K</jats:italic><jats:italic>p</jats:italic>. The <jats:italic>L</jats:italic> dependence of <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/jgra51576-math-0002.png" xlink:title="urn:x-wiley:jgra:media:jgra51576:jgra51576-math-0002"/> is systematically studied and is shown to depend on <jats:italic>K</jats:italic><jats:italic>p</jats:italic>. More significantly, we conclude that <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/jgra51576-math-0003.png" xlink:title="urn:x-wiley:jgra:media:jgra51576:jgra51576-math-0003"/>is the dominant term driving radial diffusion, typically exceeding <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/jgra51576-math-0004.png" xlink:title="urn:x-wiley:jgra:media:jgra51576:jgra51576-math-0004"/> by 1–2 orders of magnitude.</jats:p>