Correlated optical and ULF magnetic observations of the winter cusp - Boundary layer system

摘要: We have found a consistent correlation between ground based ultra low frequency (ULF) magnetic and optical measurements of the dayside cusp/boundary layer system which, we believe, may allow identification boundary layers central cusp. our analysis on data taken at Longyearbyen Svalbard, Norway. Under normal conditions, as station rotates beneath auroral zone each day it passes under ionospheric projection cusp-boundary system, near noon approximately 0830 UT. During passage distinctive sequence spectral features is observed. The characterized by sharp increase in power density broad band, unpolarized noise, combined with polarized (1–3 mHz) signal. This followed period greatly reduced noise. A narrow band signal 3–5 mHz persists throughout this quiet which observed to be predominantly left hand before local noon. feature also appears rise cusp overhead, then falls again after Optical observations are strongly correlated data. believe their source footprint signals arise from Alfven waves spawned magnetopause propagate down field lines that map layers. As move changing geomagnetic activity, noted here not seen every day. statistical question how often, what these appear an ongoing research topic. plan address future manuscript.