Chromatic dispersion variations in ultra-long-haul transmission systems arising from seasonal soil temperature variations

Seasonal soil temperature variations cause an expected peak-to-peak chromatic dispersion variation of 375 ps/nm for NZ-DSF and 570 ps/nm for large-core fiber in a 7500 km ultra-long-haul route. This amount of seasonal chromatic dispersion variation would introduce unacceptable levels of system performance degradations to an ultra-long-haul transmission system. The exact level of degradation depends on route configuration.