Biogeochemical cycling in the global ocean: 1. A new, analytical model with continuous vertical resolution and high‐latitude dynamics

Abstract

A new, simple analytical model of ocean chemistry is presented which includes continuous vertical resolution, high‐latitude dynamics, air‐sea exchange and sea ice cover. In this high‐latitude exchange/interior diffusion‐advection (HILDA) model, ocean physics are represented by four parameters: k and w, an eddy diffusion coefficient and a deep upwelling velocity in the stratified interior; q, a rate of lateral exchange between the interior and a well‐mixed, deep polar ocean; and u, an exchange velocity between surface and deep layers in the polar ocean. First, estimates are made of ice‐free and ice‐covered areas at high latitudes, surface temperatures, and air‐sea exchange velocities from available data. Then values of the physical parameters are estimated from simultaneous, least mean square fits of model solutions for temperature (T) and “abiotic” carbon 14 (Δ14C) to interior profiles of T and Δ14C and surface layer Δ14C values all derived from available data. Best fit values for k, w, q, and u are 3.2×10−5 m2 s−1, 2.0×10−8 m s−1, 7.5×10−11 s−1 and 1.9×10−6 m s−1 respectively. These results are interpreted in terms of modes of ocean circulation and mixing and compared with results from other simplier and more complex models. In parts 2 and 3 of this series, these values for k, w, q and u are taken as inputs for studying phosphorus, oxygen, and carbon cycling in the global ocean with the HILDA model.