Further Improvements to a Single-column Ocean Model

The General Ocean Turbulence Model (GOTM) is a one-dimensional water column model for marine and limnological applications. GOTM is initialized with observed ocean temperatures and forced using observed meteorological date (downward shortwave radiation, downward longwave radiation, wind speed, relative humidity, air pressure and air temperature). In this study, we make improvements to GOTM for the purpose of modelling diurnal sea surface temperature. Three improvements are considered here: (1) A linear interpolation scheme that conserves mean quantities, (2) the ocean albedo calculation, and (3) the radiant heating calculation for the upper ocean. Albedo is the reflection coefficient defined as the ratio of upward to downward irradiation, α = EU/ED. The previous method for determining ocean albedo in GOTM had relied on empirical measurements taken over a 4-month period in 1972 classified by atmospheric transmittance, latitude and solar angle only. The albedo is now explicitly calculated from its 4 major components—direct Fresnel surface, direct ocean volume, diffuse Fresnel surface and diffuse ocean volume; and takes into account chlorophyll concentration, ocean optical properties, wavelength of irradiation, atmospheric transmittance and wind speed. Radiation transmission through the ocean column is dependent on wavelength. Different parameterizations have been compared including those that use chlorophyll concentration, cloud, and inherent optical properties