On the logarithmic correction of transition fronts in shifting environments

In this paper, we investigate the location of the spreading front and convergence to traveling wave profile of solutions to the Fisher-KPP equation in the following two cases: (i) in unbounded domains with an expanding boundary; (ii) on the real line where the environment function has a shifting jump discontinuity. Our approach is based on extending ideas in Bramson’s seminal work in 1983, and applying gluing technique to construct super/subsolutions.