A geometric model for the Beaufort Chukchi Sea thermohaline structure

A geometric model has been developed for analyzing observed Beaufort/Chukch i Sea temperature and salinity profiles based on their geometric features. It contains four major components: (a) a nonhomogeneous mesh difference sch eme for second derivatives partial derivative(2)T(z(k))/partial derivative z(2) and partial derivative(2)S(z(k))/partial derivative z(2) at each data point (z(k), T-k, S-k); (b) a set of key depths (depths of mixed layer, upp er and lower thermoclines and haloclines, and deep layers) determined mostl y by the geometric features of profiles, such as depths of minimum and maxi mum of partial derivative(2)T(z(k))/partial derivative z(2) and partial der ivative(2)S(z(k))/partial derivative z(2) for shelf water and upper portion deep water; (c) modeled profiles (T) over cap(z(k)) and (S) over cap(z(k)) , which are linearly interpolated from observed T, S values at the key dept hs; and (d) statistical tests for accepting [(T) over cap(z(k)), (S) over c ap(z(k))] as a good representative of (z(k), T-k, S-k). The output of this geometric model is a set of major characteristics of each profile: sea surf ace temperature (salinity), mixed layer depth, upper- and lower-thermocline (halocline) depths, thermocline (halocline) temperature (salinity) gradien t, and deep layer stratification. Analyzing 3562 Beaufort/Chukchi Sea histo rical (1970-93) temperature and salinity profiles from the Naval Oceanograp hic Office's Master Oceanographic Observation Data Set by this geometric mo del, the Beaufort/Chukchi Sea thermohaline field reveals a dual structure: one layer (vertically uniform) on the continental shelf (depth < 150 m) dur ing winter and multiple layers (mixed layer, thermocline/halocline, sublaye r) during summer. Strong seasonal variations were also found in mixed layer depth, upper thermocline/halocline depth, and strength.