Tidal Characteristic Numbers of Salinity: Difference between revisions
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==Motivation== | ==Motivation== | ||
The calculation as well as the graphic visualization of various tidal characteristic numbers of salinity and also for the advective transport of salt contributes to an improved understanding of tidally dominated transport processes in estuaries. Spatial variations of salinity, advective transport of salt by means of flood and ebb currents can be highlighted for areas like coastal seas and estuaries as well (see also [[Example: Animation of Salinity in the Außenweser Estuary|animation of tidal variability of salinity]] in the Außenweser Estuary). | The calculation as well as the graphic visualization of various tidal characteristic numbers of salinity and also for the advective transport of salt contributes to an improved understanding of tidally dominated transport processes in estuaries. Spatial variations of salinity, advective transport of salt by means of [[flood]] and ebb currents can be highlighted for areas like coastal seas and estuaries as well (see also [[Example: Animation of Salinity in the Außenweser Estuary|animation of tidal variability of salinity]] in the Außenweser [[Estuary]]). | ||
* 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. | * 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 salinity resulting from the local maximum as well as the local minimum of salinity can be quite large. This is a consequence of fresh water inflow into an estuary. The value for the local salinity variation is mainly the result of the product between the horizontal salinity gradient and the lagrangian drift of a water particle during a complete tidal cycle. Due to the fact that salt is mainly advectively transported by means of the tidal current. The water particles which are passing at a location during a complete tidal cycle do have different regions of origin. Therefore they can also show substantial differences in salinity because estuaries are regions where fresh and sea water is mixed. For organisms which are living at the seabed and which cannot move the tidal variation of salinity is one of the significant natural stress factors (variation of the osmotic pressure due to salinity variations). | * The variation of salinity resulting from the local maximum as well as the local minimum of salinity can be quite large. This is a consequence of fresh water inflow into an [[estuary]]. The value for the local salinity variation is mainly the result of the product between the horizontal salinity [[gradient]] and the lagrangian drift of a water particle during a complete tidal cycle. Due to the fact that salt is mainly advectively transported by means of the tidal current. The water particles which are passing at a location during a complete tidal cycle do have different regions of origin. Therefore they can also show substantial differences in salinity because estuaries are regions where fresh and sea water is mixed. For organisms which are living at the seabed and which cannot move the tidal variation of salinity is one of the significant natural stress factors (variation of the osmotic pressure due to salinity variations). | ||
'''Automatic analyses for all of the above mentioned tidal characteristic numbers of salinity are carried out for 2D- as well as for 3D-data by the programs [[TDKSF]] and [[NCANALYSE]].''' | Multiple characteristic numbers can be computed also for the duration of [[flood]] (not duration of [[flood]] current) and the duration of ebb (not ebb current). | ||
'''Automatic analyses for all of the above mentioned tidal characteristic numbers of salinity are carried out for 2D- as well as for 3D-data by the programs [[TDKSF]] and [[NCANALYSE]]''' (modes '''TDKS''' ([[flood]] current, ebb current) and '''TDWS''' ([[flood]], ebb)). | |||
For modes '''TDKS''' and '''TDWS''' the periods of analysis and integration are differently defined: | |||
* mode '''TDKS''' | |||
** [[flood]] current: period between ebb slack (or start of flooding) and [[flood]] slack; | |||
** ebb current: period between [[flood]] slack and ebb slack (or end of flooding); | |||
** tide: period between first ebb slack (or start of flooding) and second ebb slack (or end of flooding). | |||
* mode '''TDWS''' | |||
** [[flood]]: period between tidal low water (or start of flooding) and tidal high water; | |||
** ebb: period between tidal high water and tidal low water (or end of flooding); | |||
** tide: period between first tidal low water (or start of flooding) and second tidal low water (or end of flooding). | |||
==Definitions for the Tidal Characteristic Numbers of Salinity== | ==Definitions for the Tidal Characteristic Numbers of Salinity== | ||
| Line 18: | Line 30: | ||
====Advective Flood Transport of Salt==== | ====Advective Flood Transport of Salt==== | ||
=====Computed from synoptic current velocity and synoptic salinity===== | =====Computed from synoptic current velocity and synoptic salinity===== | ||
salt volume, which is transported by means of flood current through a cross section.<br /> | salt volume, which is transported by means of [[flood]] current through a cross section.<br /> | ||
[[Example: Advective Flood Transport of Salt in the Inner Außenweser]]. <br /> | [[Example: Advective Flood Transport of Salt in the Inner Außenweser]]. <br /> | ||
Data analysis: [[TDKSF]]. | Data analysis: [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume of salt (with exception of roundoff) which passes a certain cross section during flood current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). <br /> | Exact volume of salt (with exception of roundoff) which passes a certain cross section during [[flood]] current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 29: | Line 41: | ||
Not computed by program [[TDKSF]]. | Not computed by program [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume of salt (with exception of roundoff) which passes a certain cross section during flood current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). <br /> | Exact volume of salt (with exception of roundoff) which passes a certain cross section during [[flood]] current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 36: | Line 48: | ||
Not computed by program [[TDKSF]]. | Not computed by program [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during flood current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quantity is computed for the period of inundation only. <br /> | Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during [[flood]] current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quantity is computed for the period of inundation only. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 43: | Line 55: | ||
Not computed by program [[TDKSF]]. | Not computed by program [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during flood current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quanmtity is computed for the period of inundation only. <br /> | Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during [[flood]] current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quanmtity is computed for the period of inundation only. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
====Mean Salinity Flood Current==== | ====Mean Salinity Flood Current==== | ||
Mean value of salinity during the flood current duration of a tide.<br /> | Mean value of salinity during the [[flood]] current duration of a tide.<br /> | ||
[[Example figures: mean salinity flood current]]. <br /> | [[Example figures: mean salinity flood current]]. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 59: | Line 71: | ||
Data analysis: [[TDKSF]]. | Data analysis: [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume of salt (with exception of roundoff) which passes a certain cross section during ebb current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). <br /> | Exact volume of salt (with exception of roundoff) which passes a certain cross section during ebb current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 66: | Line 78: | ||
Not computed by program [[TDKSF]]. | Not computed by program [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume of salt (with exception of roundoff) which passes a certain cross section during ebb current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). <br /> | Exact volume of salt (with exception of roundoff) which passes a certain cross section during ebb current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 73: | Line 85: | ||
Not computed by program [[TDKSF]]. | Not computed by program [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during ebb current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quantity is computed for the period of inundation only. <br /> | Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during ebb current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quantity is computed for the period of inundation only. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 80: | Line 92: | ||
Not computed by program [[TDKSF]]. | Not computed by program [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | =====Computed from integral (salt) volume transport===== | ||
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during ebb current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this | Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during ebb current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). On tidal flats this quantity is computed for the period of inundation only. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
====Mean Salinity Ebb Current==== | ====Mean Salinity Ebb Current==== | ||
| Line 88: | Line 100: | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
===Tidal Cycle=== | ===Tidal Cycle (between two subsequent ebb slacks)=== | ||
====Maximum Salinity==== | ====Maximum Salinity==== | ||
| Line 111: | Line 123: | ||
====Advective Residual Transport of Salt==== | ====Advective Residual Transport of Salt==== | ||
residual salt volume 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 salt.<br /> | residual salt volume 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 salt.<br /> | ||
=====Computed from synoptic current velocity and synoptic salinity===== | |||
[[Example: Advective Residual Transport of Salt in the Inner Außenweser]]. <br /> | [[Example: Advective Residual Transport of Salt in the Inner Außenweser]]. <br /> | ||
Data analysis: [[TDKSF]]. | Data analysis: [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | |||
Residual based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle ([[flood]] current plus ebb current) due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). <br /> | |||
Data analysis: [[NCANALYSE]]. | |||
====Diffusive Residual Transport of Salt==== | |||
residual salt volume which is transported by means of diffusion during ebb and [[flood]] current through a cross section (the different transport directions are taken into account). If the diffusive transport for each of the tidal phases is equal but in opposite direction this will result in a zero diffusive residual transport of salt.<br /> | |||
=====Computed from synoptic current velocity and synoptic salinity===== | |||
Not computed by program [[TDKSF]]. | |||
=====Computed from integral (salt) volume transport===== | |||
Residual based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle ([[flood]] current plus ebb current) due to diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of [[projection]] is left to visualization programs (e. g. [[NCPLOT]]). <br /> | |||
Data analysis: [[NCANALYSE]]. | |||
====Advective Tidal Transport of Salt==== | |||
total salt volume which is transported by means of advection during ebb and [[flood]] current through a cross section (the different transport directions are taken into account). Magnitudes for [[flood]] and ebb current transport are added.<br /> | |||
=====Computed from synoptic current velocity and synoptic salinity===== | |||
Not computed by program [[TDKSF]]. | |||
=====Computed from integral (salt) volume transport===== | |||
Sum of individual transports (magnitudes) based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle ([[flood]] current plus ebb current) due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. <br /> | |||
Data analysis: [[NCANALYSE]]. | |||
====Advective Salt Transport, Flood-Ebb-Ratio==== | ====Advective Salt Transport, Flood-Ebb-Ratio==== | ||
flood to ebb ratio for the salt volumes which are transported by means of flood and ebb currents.<br /> | [[flood]] to ebb ratio for the salt volumes which are transported by means of [[flood]] and ebb currents.<br /> | ||
=====Computed from synoptic current velocity and synoptic salinity===== | |||
[[Example: Flood-Ebb-Ratio for the Advective Salt Transport in the Inner Außenweser]]. <br /> | [[Example: Flood-Ebb-Ratio for the Advective Salt Transport in the Inner Außenweser]]. <br /> | ||
Data analysis: [[TDKSF]]. | Data analysis: [[TDKSF]]. | ||
=====Computed from integral (salt) volume transport===== | |||
Based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle due to advection. Quantity is computed from the (face) normal components only.<br /> | |||
Data analysis: [[NCANALYSE]]. | |||
====Advective Salt Transport, Flood-Tide-Ratio==== | |||
[[flood]] to tide ratio for the salt volumes which are transported by means of [[flood]] and tide ([[flood]] plus ebb) currents.<br /> | |||
=====Computed from synoptic current velocity and synoptic salinity===== | |||
Not computed by program [[TDKSF]]. | |||
=====Computed from integral (salt) volume transport===== | |||
Based on exact volume of salt (with exception of roundoff) which passes a certain cross section due to advection. Quantity is computed from the (face) normal components only.<br /> | |||
Data analysis: [[NCANALYSE]]. | |||
====Advective Salt Transport, Ebb-Tide-Ratio==== | |||
ebb to tide ratio for the salt volumes which are transported by means of ebb and tide ([[flood]] plus ebb) currents.<br /> | |||
=====Computed from synoptic current velocity and synoptic salinity===== | |||
Not computed by program [[TDKSF]]. | |||
=====Computed from integral (salt) volume transport===== | |||
Based on exact volume of salt (with exception of roundoff) which passes a certain cross section due to advection. Quantity is computed from the (face) normal components only.<br /> | |||
Data analysis: [[NCANALYSE]]. | |||
====Mean Salinity Flood Current : Mean Salinity==== | ====Mean Salinity Flood Current : Mean Salinity==== | ||
Ratio of mean salinity of flood current to mean salinity during the complete tide.<br /> | Ratio of mean salinity of [[flood]] current to mean salinity during the complete tide.<br /> | ||
[[Example figures: mean salinity flood current : mean salinity]]. <br /> | [[Example figures: mean salinity flood current : mean salinity]]. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 131: | Line 183: | ||
====Mean Salinity Flood Current : Mean Salinity Ebb Current==== | ====Mean Salinity Flood Current : Mean Salinity Ebb Current==== | ||
Ratio of mean salinity of flood current to mean salinity of ebb current.<br /> | Ratio of mean salinity of [[flood]] current to mean salinity of ebb current.<br /> | ||
[[Example figures: mean salinity flood current : mean salinity ebb current]]. <br /> | [[Example figures: mean salinity flood current : mean salinity ebb current]]. <br /> | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
| Line 150: | Line 202: | ||
Data analysis: [[NCANALYSE]]. | Data analysis: [[NCANALYSE]]. | ||
===Flood=== | |||
====Mean Salinity Flood==== | |||
Mean value of salinity during [[flood]] duration of a tide. This value is typically lower than the respective mean computed for [[flood]] current duration.<br /> | |||
<!-- [[Example figures: mean salinity during flood]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
===Ebb=== | |||
====Mean Salinity Ebb==== | |||
Mean value of salinity during ebb duration of a tide. This value is typically larger than the respective mean computed for ebb current duration.<br /> | |||
<!-- [[Example figures: mean salinity ebb current]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
===Tidal Cycle (between two subsequent tidal low waters)=== | |||
====Maximum Salinity==== | |||
Maximum value of salinity during a complete tidal cycle (period between two subsequent tidal low [[waters]]). This value is typically identical to the respective maximum computed for the period between two subsequent ebb slacks.<br /> | |||
<!-- [[Example figures: maximum salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Minimum Salinity==== | |||
Minimum value of salinity during a complete tidal cycle (period between two subsequent tidal low [[waters]]). This value may differ from the respective minimum computed for the period between two subsequent ebb slacks.<br /> | |||
<!-- [[Example figures: minimum salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Mean Salinity==== | |||
Average value of salinity during a complete tidal cycle (period between two subsequent tidal low [[waters]]). This value is typically comparable to the respective mean computed for the period between two subsequent ebb slacks.<br /> | |||
<!-- [[Example figures: mean salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Tidal Variation of Salinity==== | |||
Difference between the extreme values of salinity during a complete tidal cycle (period between two subsequent tidal low [[waters]]). This value may differ from the respective value computed for the period between two subsequent ebb slacks.<br /> | |||
<!-- [[Example figures: tidal variation of salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Mean Salinity Flood : Mean Salinity==== | |||
Ratio of mean salinity of [[flood]] to mean salinity during the complete tide (period between two subsequent tidal low [[waters]]).<br /> | |||
<!-- [[Example figures: mean salinity flood : mean salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Mean Salinity Ebb : Mean Salinity==== | |||
Ratio of mean salinity of ebb to mean salinity during the complete tide (period between two subsequent tidal low [[waters]]).<br /> | |||
<!-- [[Example figures: mean salinity ebb : mean salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Mean Salinity Flood : Mean Salinity Ebb==== | |||
Ratio of mean salinity of during [[flood]] to mean salinity during ebb.<br /> | |||
<!-- [[Example figures: mean salinity flood : mean salinity ebb]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Tidal Variation of Salinity : Mean Salinity==== | |||
Ratio of tidal variation of salinity to mean salinity value of the tide (period between two subsequent tidal low [[waters]]).<br /> | |||
<!-- [[Example figures: tidal variation of salinity : mean salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Maximum Salinity : Mean Salinity==== | |||
Ratio of maximum salinity of the tide to mean salinity value of the tide (period between two subsequent tidal low [[waters]])..<br /> | |||
<!-- [[Example figures: maximum salinity : mean salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
====Minimum Salinity : Mean Salinity==== | |||
Ratio of minimum salinity of the tide to mean salinity value of the tide (period between two subsequent tidal low [[waters]])..<br /> | |||
<!-- [[Example figures: minimum salinity : mean salinity]]. <br /> --> | |||
Data analysis: [[NCANALYSE]]. | |||
---- | ---- | ||
back to [[Analysis of Calculated Results]] | back to [[Analysis of Calculated Results]] | ||
---- | ---- | ||
[[Overview]] | [[Overview]] | ||
Latest revision as of 09:25, 21 October 2022
Graphical representation of characteristic numbers of salinity (with German text only). This graphical representation is also available in Encapsulated PostScript format.
Graphical representation of characteristic numbers of advective salt transport (with German text only). This graphical representation is also available in Encapsulated PostScript format.
Motivation
The calculation as well as the graphic visualization of various tidal characteristic numbers of salinity and also for the advective transport of salt contributes to an improved understanding of tidally dominated transport processes in estuaries. Spatial variations of salinity, advective transport of salt by means of flood and ebb currents can be highlighted for areas like coastal seas and estuaries as well (see also animation of tidal variability of salinity in the Außenweser Estuary).
- 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 salinity resulting from the local maximum as well as the local minimum of salinity can be quite large. This is a consequence of fresh water inflow into an estuary. The value for the local salinity variation is mainly the result of the product between the horizontal salinity gradient and the lagrangian drift of a water particle during a complete tidal cycle. Due to the fact that salt is mainly advectively transported by means of the tidal current. The water particles which are passing at a location during a complete tidal cycle do have different regions of origin. Therefore they can also show substantial differences in salinity because estuaries are regions where fresh and sea water is mixed. For organisms which are living at the seabed and which cannot move the tidal variation of salinity is one of the significant natural stress factors (variation of the osmotic pressure due to salinity variations).
Multiple characteristic numbers can be computed also for the duration of flood (not duration of flood current) and the duration of ebb (not ebb current).
Automatic analyses for all of the above mentioned tidal characteristic numbers of salinity are carried out for 2D- as well as for 3D-data by the programs TDKSF and NCANALYSE (modes TDKS (flood current, ebb current) and TDWS (flood, ebb)).
For modes TDKS and TDWS the periods of analysis and integration are differently defined:
- mode TDKS
- mode TDWS
- flood: period between tidal low water (or start of flooding) and tidal high water;
- ebb: period between tidal high water and tidal low water (or end of flooding);
- tide: period between first tidal low water (or start of flooding) and second tidal low water (or end of flooding).
Definitions for the Tidal Characteristic Numbers of Salinity
Flood Current
Advective Flood Transport of Salt
Computed from synoptic current velocity and synoptic salinity
salt volume, which is transported by means of flood current through a cross section.
Example: Advective Flood Transport of Salt in the Inner Außenweser.
Data analysis: TDKSF.
Computed from integral (salt) volume transport
Exact volume of salt (with exception of roundoff) which passes a certain cross section during flood current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).
Data analysis: NCANALYSE.
Diffusive Flood Transport of Salt
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Exact volume of salt (with exception of roundoff) which passes a certain cross section during flood current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).
Data analysis: NCANALYSE.
Advective Flood Transport-Rate of Salt
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during flood current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT). On tidal flats this quantity is computed for the period of inundation only.
Data analysis: NCANALYSE.
Diffusive Flood Transport-Rate of Salt
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during flood current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT). On tidal flats this quanmtity is computed for the period of inundation only.
Data analysis: NCANALYSE.
Mean Salinity Flood Current
Mean value of salinity during the flood current duration of a tide.
Example figures: mean salinity flood current.
Data analysis: NCANALYSE.
Ebb Current
Advective Ebb Transport of Salt
Computed from synoptic current velocity and synoptic salinity
salt volume, which is transported by means of ebb current through a cross section.
Example: Advective Ebb Transport of Salt in the Inner Außenweser.
Data analysis: TDKSF.
Computed from integral (salt) volume transport
Exact volume of salt (with exception of roundoff) which passes a certain cross section during ebb current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).
Data analysis: NCANALYSE.
Diffusive Ebb Transport of Salt
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Exact volume of salt (with exception of roundoff) which passes a certain cross section during ebb current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).
Data analysis: NCANALYSE.
Advective Ebbe Transport-Rate of Salt
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during ebb current due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT). On tidal flats this quantity is computed for the period of inundation only.
Data analysis: NCANALYSE.
Diffusive Ebb Transport-Rate of Salt
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Exact volume transport rate of salt (with exception of roundoff) which passes a certain cross section during ebb current due to (turbulent) diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT). On tidal flats this quantity is computed for the period of inundation only.
Data analysis: NCANALYSE.
Mean Salinity Ebb Current
Mean value of salinity during the ebb current duration of a tide.
Example figures: mean salinity ebb current.
Data analysis: NCANALYSE.
Tidal Cycle (between two subsequent ebb slacks)
Maximum Salinity
maximum value of salinity during a complete tidal cycle (period between two subsequent slack water times of ebb current).
Example figures: maximum salinity.
Data analysis: TDKSF and NCANALYSE.
Minimum Salinity
minimum value of salinity during a complete tidal cycle (period between two subsequent slack water times of ebb current).
Example figures: minimum salinity.
Data analysis: TDKSF and NCANALYSE.
Mean Salinity
average value of salinity during a complete tidal cycle (period between two subsequent slack water times of ebb current).
Example figures: mean salinity.
Data analysis: TDKSF and NCANALYSE.
Tidal Variation of Salinity
difference between the extreme values of salinity during a complete tidal cycle (period between two subsequent slack water times of ebb current).
Example figures: tidal variation of salinity.
Data analysis: TDKSF and NCANALYSE.
Advective Residual Transport of Salt
residual salt volume 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 salt.
Computed from synoptic current velocity and synoptic salinity
Example: Advective Residual Transport of Salt in the Inner Außenweser.
Data analysis: TDKSF.
Computed from integral (salt) volume transport
Residual based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle (flood current plus ebb current) due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).
Data analysis: NCANALYSE.
Diffusive Residual Transport of Salt
residual salt volume which is transported by means of diffusion during ebb and flood current through a cross section (the different transport directions are taken into account). If the diffusive transport for each of the tidal phases is equal but in opposite direction this will result in a zero diffusive residual transport of salt.
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Residual based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle (flood current plus ebb current) due to diffusion. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).
Data analysis: NCANALYSE.
Advective Tidal Transport of Salt
total salt volume which is transported by means of advection during ebb and flood current through a cross section (the different transport directions are taken into account). Magnitudes for flood and ebb current transport are added.
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Sum of individual transports (magnitudes) based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle (flood current plus ebb current) due to advection. This quantity makes use of the normal flow of salt only, which is orthogonal to the flow face.
Data analysis: NCANALYSE.
Advective Salt Transport, Flood-Ebb-Ratio
flood to ebb ratio for the salt volumes which are transported by means of flood and ebb currents.
Computed from synoptic current velocity and synoptic salinity
Example: Flood-Ebb-Ratio for the Advective Salt Transport in the Inner Außenweser.
Data analysis: TDKSF.
Computed from integral (salt) volume transport
Based on exact volume of salt (with exception of roundoff) which passes a certain cross section during a tidal cycle due to advection. Quantity is computed from the (face) normal components only.
Data analysis: NCANALYSE.
Advective Salt Transport, Flood-Tide-Ratio
flood to tide ratio for the salt volumes which are transported by means of flood and tide (flood plus ebb) currents.
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Based on exact volume of salt (with exception of roundoff) which passes a certain cross section due to advection. Quantity is computed from the (face) normal components only.
Data analysis: NCANALYSE.
Advective Salt Transport, Ebb-Tide-Ratio
ebb to tide ratio for the salt volumes which are transported by means of ebb and tide (flood plus ebb) currents.
Computed from synoptic current velocity and synoptic salinity
Not computed by program TDKSF.
Computed from integral (salt) volume transport
Based on exact volume of salt (with exception of roundoff) which passes a certain cross section due to advection. Quantity is computed from the (face) normal components only.
Data analysis: NCANALYSE.
Mean Salinity Flood Current : Mean Salinity
Ratio of mean salinity of flood current to mean salinity during the complete tide.
Example figures: mean salinity flood current : mean salinity.
Data analysis: NCANALYSE.
Mean Salinity Ebb Current : Mean Salinity
Ratio of mean salinity of ebb current to mean salinity during the complete tide.
Example figures: mean salinity ebb current : mean salinity.
Data analysis: NCANALYSE.
Mean Salinity Flood Current : Mean Salinity Ebb Current
Ratio of mean salinity of flood current to mean salinity of ebb current.
Example figures: mean salinity flood current : mean salinity ebb current.
Data analysis: NCANALYSE.
Tidal Variation of Salinity : Mean Salinity
Ratio of tidal variation of salinity to mean salinity value of the tide.
Example figures: tidal variation of salinity : mean salinity.
Data analysis: NCANALYSE.
Maximum Salinity : Mean Salinity
Ratio of maximum salinity of the tide to mean salinity value of the tide.
Example figures: maximum salinity : mean salinity.
Data analysis: NCANALYSE.
Minimum Salinity : Mean Salinity
Ratio of minimum salinity of the tide to mean salinity value of the tide.
Example figures: minimum salinity : mean salinity.
Data analysis: NCANALYSE.
Flood
Mean Salinity Flood
Mean value of salinity during flood duration of a tide. This value is typically lower than the respective mean computed for flood current duration.
Data analysis: NCANALYSE.
Ebb
Mean Salinity Ebb
Mean value of salinity during ebb duration of a tide. This value is typically larger than the respective mean computed for ebb current duration.
Data analysis: NCANALYSE.
Tidal Cycle (between two subsequent tidal low waters)
Maximum Salinity
Maximum value of salinity during a complete tidal cycle (period between two subsequent tidal low waters). This value is typically identical to the respective maximum computed for the period between two subsequent ebb slacks.
Data analysis: NCANALYSE.
Minimum Salinity
Minimum value of salinity during a complete tidal cycle (period between two subsequent tidal low waters). This value may differ from the respective minimum computed for the period between two subsequent ebb slacks.
Data analysis: NCANALYSE.
Mean Salinity
Average value of salinity during a complete tidal cycle (period between two subsequent tidal low waters). This value is typically comparable to the respective mean computed for the period between two subsequent ebb slacks.
Data analysis: NCANALYSE.
Tidal Variation of Salinity
Difference between the extreme values of salinity during a complete tidal cycle (period between two subsequent tidal low waters). This value may differ from the respective value computed for the period between two subsequent ebb slacks.
Data analysis: NCANALYSE.
Mean Salinity Flood : Mean Salinity
Ratio of mean salinity of flood to mean salinity during the complete tide (period between two subsequent tidal low waters).
Data analysis: NCANALYSE.
Mean Salinity Ebb : Mean Salinity
Ratio of mean salinity of ebb to mean salinity during the complete tide (period between two subsequent tidal low waters).
Data analysis: NCANALYSE.
Mean Salinity Flood : Mean Salinity Ebb
Ratio of mean salinity of during flood to mean salinity during ebb.
Data analysis: NCANALYSE.
Tidal Variation of Salinity : Mean Salinity
Ratio of tidal variation of salinity to mean salinity value of the tide (period between two subsequent tidal low waters).
Data analysis: NCANALYSE.
Maximum Salinity : Mean Salinity
Ratio of maximum salinity of the tide to mean salinity value of the tide (period between two subsequent tidal low waters)..
Data analysis: NCANALYSE.
Minimum Salinity : Mean Salinity
Ratio of minimum salinity of the tide to mean salinity value of the tide (period between two subsequent tidal low waters)..
Data analysis: NCANALYSE.
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