Cross-sections of sigma-0 along 33W to a depth of 500m for summer (top) and to 3000m for winter (bottom). The thick line is the mixed layer base. Winter and summer fields simulated by HYCOM run with the two hybrid K-T mixed layer models (both with implicit diapycnal diffusion) differ substantially, with the K-T 1 simulations more-closely resembling the observations (see next slide).