As with direct current measurements, time series signals must be averaged or filtered. Velocities associated with the general circulation are then mostly calculated from the pressure gradients, with a number of techniques used to estimate the absolute pressure at each point and hence the absolute velocity. 1.2 Dynamic height. To calculate pressure at a point relative to a deeper or shallower point at the same horizontal location, from the measured density field. The practical details of the calculation are beyond the scope of these notes and class, but an example is worked through in class.
Transports are the total flux of whatever property through a given area.
We can also calculate a vertical transport through a horizontal or isopycnal surface. Heat must be calculated using Kelvin degrees, and potential temperature rather than temperature. Heat transport through a closed area, through which there is no net mass transport, is basically proportional to the temperature difference between water entering and water leaving across the closed boundaries, so degrees Celsius are fine for this practical use. However freshwater is exchanged with the atmosphere and land. A kilogram of seawater consists of a portion of water and a portion of salt.