FRAM (Fine Resolution Antarctic Model)


Posted March 20, 2002,18:33
Institution: Southampton Oceanography Centre
Contact: bac@soc.soton.ac.uk
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FRAM is a primitive equation numerical model of the Southern Ocean between latitudes 24S and 79S. The code is based on that of Cox. The model starts from rest with initial temperature of -2C and salinity 36.69 everywhere, and relaxes to the Levitus annual mean temperature and salinity over 6 years. For the first 2 years 160 days, the relaxation timescale is 180 days for depths above 160 m and 540 days for the deeper levels. From then until 6 years the timescale is 360 days throughout. This is equivalent to the normal robust diagnostic scheme, except that the relaxation is so weak that the eddy field can develop. Surface forcing (Hellerman annual mean winds), is introduced after 2 years 6 months - increasing linearly from zero to the mean values over 6 months. After 6 years seasonal winds are introduced and surface forcing of temperature and salinity is operated by relaxing the surface layer only to the annual mean Levitus values with a time scale of one year. Towards the end of 9 years (day 3256), the viscosity and diffusion change from harmonic to a mixture of harmonic and biharmonic and the bottom friction changes from linear to quadratic. The model runs on to the end of 16 years.