Effect of NWC transmission projected in L-shell as indicated by 30–100- and 100–300-keV electron observations from NOAA satellites. (a) and (b) Electrons for 1 January to 31 May 2007, with those for 1 August to 31 December 2007 subtracted. The data in each period are the sum of all 30–100- or 100–300-keV electron counts from the 90° MEPEDs for the given periods. (c) and (d) Ratio of subtracted data shown above to background for 1 August to 31 December 2007. The NWC was operating normally from 1 January to 31 May 2007.