IGPP/LANL
Cross Correlations
Cross-Correlation of Waves at Two Sites
Nightside Pi 2 Pulsation
The top panel of Figure 5c shows the time series of a Pi 2 wave at LANL (blue) and SGD (red) sites. The wave data have been rotated to the wave's principle axis
coordinates and the wave maximum variance components are shown in Figure 5c. The bottom panel of Figure 5c shows the cross-correlation coefficient as a function of the
time lag between the LANL and SGD sites. The waves seen at both sites are high correlated with a maximum cross-correlation coefficient of 0.975. The wave is seen at
LANL site 2.171 seconds earlier than at SGD site. Thus, the phase of the wave propagates towards the midnight in the earlier morning sector (westward).
Dayside Pc 3-4 Pulsation
The text above was taken from IGPP at UCLA @:
Ground-Based Magnetometer Array
The accurate timing provided by the GPS receiver enables us to perform cross-correlation analysis to determine the time lag between the signals at two sites. Below we
show examples of Pi 2 and Pc 3-4 pulsations observed at LANL and SGD sites simultaneously.
Figure 5a shows an example of nightside Pi 2 pulsations observed simultaneously at Los Alamos Fenton Hill site (Top panel) and San Gabriel Dam test site (bottom
panel). Figure 5b (not currently available) shows 8-40 mHz bandpass filtered data for the same period.
Figures 6a, Figure 6b, and Figure 6c show an example of Pc 3-4 waves and are in the same format as Figures 5a, b, and c, respectively. In this case, the wave is seen at
SGD site 4.153 seconds earlier than at LANL site. Thus the phase of the wave propagates from the subsolar region towards the dusk in the
post-noon sector.
http://www-ssc.igpp.ucla.edu/uclamag/posters/agu98s/
