Solar flare-induced amplitude enhancement in NLK, NPM, and NWC signals. As a function of peak solar flare X-ray power in dB (relative to 1 μW/m2) in the 0.1 to 0.8 nm band. Much lower levels of amplitude perturbations are noted for the NPM (max. of approximately 6 dB) and NWC (max. of approximately 3.5 dB) signals compared to the NLK (max. of approximately 11.5 dB).