Transfer of heat, fresh water and nutrients through the seasonal thermocline

Abstract
This paper estimates the turbulent transport of heat, fresh water and nutrients through the seasonal thermocline. In order to obtain a representative estimate of the annual variation it is necessary to average data obtained at a single position over a number of years. The number of years of sampling required depends on the particular parameter being studied. This can be seen by comparing the annual variation with the standard deviation, σ, for a specific month. This is analogous to the signal to noise ratio. For example, the annual range of temperature (or signal) is about 8°C for the water of the western English Channel. The variability of temperature in the same area (or noise) is about o.6°C. This figure is the standard deviation for the temperature obtained in a specific month at a fixed depth when data from a large number of different years are available. This variability can be attributed to a number of causes, to list a few; horizontal patchiness, local weather, advection, long term climatic changes. Hence for temperature the signal to noise ratio is about 13 and the annual pattern of events will clearly be established on the basis of monthly values obtained at a position during a single year.
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