  In addition to the dominant oscillatory gravitational wave signals produced
during binary inspirals, a non-oscillatory component arises from the nonlinear
"memory" effect, sourced by the emitted gravitational radiation. The memory
grows significantly during the late inspiral and merger, modifying the signal
by an almost step-function profile, and making it difficult to model by
approximate methods. We use numerical evolutions of binary black holes to
evaluate the nonlinear memory during late-inspiral, merger and ringdown. We
identify two main components of the signal: the monotonically growing portion
corresponding to the memory, and an oscillatory part which sets in roughly at
the time of merger and is due to the black hole ringdown. Counter-intuitively,
the ringdown is most prominent for models with the lowest total spin. Thus, the
case of maximally spinning black holes anti-aligned to the orbital angular
momentum exhibits the highest signal-to-noise (SNR) for interferometric
detectors. The largest memory offset, however, occurs for highly spinning black
holes, with an estimated value of h^tot_20 \approx 0.24 in the maximally
spinning case. These results are central to determining the detectability of
nonlinear memory through pulsar timing array measurements.
