> Surely they mean that it tracks the actual tides?
No, they mean it computes the value (as a function of time) of a harmonic series with 42 parameters which ideally will correspond to the tides at some specific location.
It's not in any way "tracking" or connected to the actual tides.
If you think of some idealised tidal bulge (pairs! one either side of the earth) tracking about the globe in response to the motion of the moon, that's the baseline "tide" .. now imagine that tidal bulge being funnelled between the narrow gap between Australia and PNG .. that's a complication .. now imagine that being slowed and channelled by various islands and headlands before being squeezed into a horizontal waterfall (something to look up ).
That specific geographic location experiences a unique pattern of tides that are driven by the primary earth|moon dynamics but transposed, amplified, and delayed in a complex manner that can be described(?) by a set of parameters that take some effort to derive.
The Doodson-Légé Tide Predicting Machine has a go at that task using 42 parameters, modern computing tables might require 120 or so, and both systems would routinely require parameters to be updated in response to computational drift and changes in landform (erosion, silt and mud build up, new channels being carved out, etc).
No, they mean it computes the value (as a function of time) of a harmonic series with 42 parameters which ideally will correspond to the tides at some specific location.
It's not in any way "tracking" or connected to the actual tides.
If you think of some idealised tidal bulge (pairs! one either side of the earth) tracking about the globe in response to the motion of the moon, that's the baseline "tide" .. now imagine that tidal bulge being funnelled between the narrow gap between Australia and PNG .. that's a complication .. now imagine that being slowed and channelled by various islands and headlands before being squeezed into a horizontal waterfall (something to look up ).
That specific geographic location experiences a unique pattern of tides that are driven by the primary earth|moon dynamics but transposed, amplified, and delayed in a complex manner that can be described(?) by a set of parameters that take some effort to derive.
The Doodson-Légé Tide Predicting Machine has a go at that task using 42 parameters, modern computing tables might require 120 or so, and both systems would routinely require parameters to be updated in response to computational drift and changes in landform (erosion, silt and mud build up, new channels being carved out, etc).