Tidal Characteristic Numbers of Tracer Load

A graphic sketch for the definition of the various tidal characteristic numbers of tracer load is not available. Due to the fact that they are defined in complete analogy to salinity we do refer here to the respective graphical representations of the tidal characteristic numbers of salinity for further insight.

Motivation

The calculation as well as the graphic visualization of various tidal characteristic numbers of tracer concentration and also for the advective transport of tracer contributes to an improved understanding of tidally dominated transport processes in estuaries. Spatial variations of tracer concentration, advective transport of tracer load by means of flood and ebb currents can be highlighted for areas like coastal seas and estuaries as well.

• As the calculations are performed separately for the durations of ebb- and flood-current it can be shown that transport paths can differ significantly for the two tidal phases. From this one can get additional insight with respect to the relevant transport mechanisms dominated by the tidal currents. This can be related to locally varying flood-ebb asymmetries for ebb volume and flood volume. Also the presence of horizontal gradients can contribute to this effect.

• The variation of tracer concentration resulting from the local maximum as well as the local minimum of tracer concentration can be quite large. This is a consequence of the different availability of tracer load, e. g. inside or outside of the turbidity maximum. The value for the local tracer concentration variation is mainly the result of the product between the horizontal tracer concentration gradient and the lagrangian drift of a water particle during a complete tidal cycle, but also effected by the strong spatial variation of deposition and erosion of tracers throughout the estuary.

An automatic analysis of all tidal characteristic numbers of tracer load is carried through by the computer programs TDKSF and NCANALYSE.

Definitions for the Tidal Characteristic Numbers of Tracer Transport

Program TDKSF

Flood Current

Advective Flood Transport of Tracer Load

Tracer load, which is transported by means of flood current through a cross section
Example: not available.

Ebb Current

Advective Ebb Transport of Tracer Load

Tracer load, which is transported by means of ebb current through a cross section
Example: not available.

Tidal Cycle

Maximum Tracer Concentration

Maximum value of tracer concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Minimum Tracer Concentration

Minimum value of tracer concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Mean Tracer Concentration

Average value of tracer concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Tidal Variation of Tracer Concentration

Difference between the extreme values of tracer concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Advective Residual Transport of Tracer Load

Residual tracer load which is transported by means of ebb and flood currents through a cross section (the different transport directions are taken into account). If the advective transport by means of flood current is equal but in opposite direction of the ebb current transport this will result in a zero advective residual transport of tracer load.
Example: not available.

Advective Tracer Transport, Flood-Ebb-Ratio

Flood to ebb ratio for the tracer load which are transported by means of flood and ebb currents
Example: not available.

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