Numerical Simulation of Summer Warming of Siberian Shelf Seas Depending on Short-Wave Radiation Parameterization

The main source of summer heating of the upper layer of Siberian Arctic shelf seas is shortwave solar radiation. The radiation flux attenuates as it passes through the water depth, and the attenuation rate is determined by the optical properties of water, which mainly depend on the concentration of suspended matter in the water. In numerical models of the ocean and sea ice, the process of shortwave solar radiation absorption is described by different parameterizations. In this work, the sensitivity of the numerical 3D regional ocean and sea ice model SibCIOM to two parameterizations of the penetrating radiation is studied: (1) two-component parameterization with constant attenuation coefficients for the infrared and visible spectral regions depending on one of ten ocean water transparency classes; (2) three-component parameterization with different absorption coefficients for the red, green, and blue parts of the visible spectrum, which is based on satellite data on chlorophyll concentration. The analysis of the results of numerical experiments for the water area of Siberian shelf seas has shown that if the seasonal distribution of chlorophyll concentration is taken into account when simulating a penetrating shortwave radiation flux with the RGB parameterization, then regions of water warming are formed in the surface or bottom layer, which differ from a basic experiment with the two-component parameterization. The comparison between the simulation results with observations shows the RGB parameterization to be preferable for the numerical simulation of Arctic shelf seas.