After investigating 3,709 Beaufort Sea and adjacent seas historical (1970-1993) temperature and salinity profiles from the Naval Oceanographic Office (NAVOCEANO)'s Master Oceanographic Observation Data Set (MOODS), we found two types of salinity profiles and three types of temperature profiles. Type-I of both T, S profiles is characterized as a single-layer over the Beaufort/Chuckchi Sea shelf (depth < 150 m) or a multi-layer structure consisting a deep mixed layer (deeper than 150 m) and a lower halocline in the Beaufort Sea deep water (depth > 150 m). Type-II of S-profiles is a multi-layer structure with an upper halocline and a lower halocline both featuring monotonic increasing S with depth. Types II and III T-profiles have multi-layer structures, which include mixed-layer, entrainment zone, upper and lower thermoclines, and sub-layer. The lower thermocline is always characterized as a monotonic increasing T with depth. However, the upper thermocline has different features: monotonic decreasing T with depth (Type-II), and a nose-shape profiles (Type III, monotonic increasing T with depth to a maximum value Tmax and then monotonic decreasing with depth).
These features can be easily depicted by first-order and second-order derivatives. Such as for Type-I T, S profiles in shelf regions, the first derivative is nearly zero. For Type-II S profiles, the second derivative has a maximum/minimum at top/bottom of the upper halocline. For Type-III T-profiles, the second derivative has maxima at both top and bottom of the upper thermocline and a zero value at the depth of Tmax.