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Subsections


spm.F


subroutine spminit

spminit

Description Initialise the SPM and bottom concentrations the default is 1.5 gm$^3$ for SPM and 200.0 gm$^2$ for bed set homogenousr over the entire domain.

Subroutine Arguments

none

Local variables

i,j,k,kk Grid indeces and SPM class index

Logical units

none

Order of Things

  1. Set SPM concentration.
  2. Set bed concentration.

Calls

none

Called By

b3dinit

Options - Logical

none

Options - Compiler

none


subroutine spmsubmodel

Description

The subroutine calculates SPM transport, depostion and erosion of non-cohesive particulate matter. It takes into account the input of land and riverine sources by prescriving the concentration at a particular model grid point near the boundary. Deposition and erosion are dependent on critical stresses, which are generally different, on the ammount of erodible matterial available and from settling velocity. The model is set to include any number of sediment classes though the settling velocities.

Numerical Equations

The SPM sources are included by updating the concentration at the source points around the boundary; the change in of concentration for the i-th fraction is:

\begin{displaymath}
\frac{\partial C_i }{\partial t} = \frac{S_i }{N_i V}F_i (t)
\end{displaymath}

Where $C_i$ is the concentration for the i-th class. $N_i$ is the number of input points dor source i and V is the volume of the factional grid box sorrounding the input point. $F_i(t)$ is the normalise variation of the source.

SPM Concentration is transferred between the lowest level of the model and the bed layer by resuspension and depostion:

\begin{displaymath}
\begin{array}{l}
\frac{\partial C_i }{\partial t} = \frac{\...
... C_i }{\partial t}\Delta
z,\quad B_i > 0 \\
\\
\end{array}\end{displaymath}

Where $\epsilon$ is the erosion constant, $\Delta z$ is the vertical resolution, $\tau$ is the bottom stress, $\tau_{ero}$ is the critical stress for erosion, while $\tau_{dep}$ is the critical stress for deposition. With $B_i$ as the bed concentration and $w_i$ the settling velocity for the i-th class respectively.

The particle settling within the water column is defined using a PPM scheme by:

\begin{displaymath}
\frac{\partial C_i }{\partial t} = - w_i \frac{\partial C_i }{\partial z}
\end{displaymath}

Where the advection is carried out by the PPM routines and the horizontal diffusion is carried out using the eddy diffusivity from the turbulence closure sche used.

Subroutine Arguments

none

Local variables

i,j,k,q,ipu,jjg,iig Grid indices.
tagfb,taggb Message passing flags.
tbed Bed stress.
spmmass Rate of change SPM of concentration near the bed.
fac Variable used to include the ratio of critical stress for erosion and deposition to the bed stress.
bedsum Total bed sediment concentration.

Global variables changed

spm,bed

Order of Things

  1. Set sediment and bed parameters.
  2. Calculate exchanges from bed and batter column due to deposition and erosion.
  3. Calculates settling of SPM using ppm advection scheme.
  4. Uses SPM source boundary condition - if required, otherwise zero net flux at boundary points

Calls

Exch3DS, Exch3DR
spmset_ppm, spmsource

Called By

b3drun

Options - Logical

lspmsource if true use source boundary condition

Options - Compiler

SCOORD

Known Issues

none


subroutine spmset_ppm

Description

Calculates settling of SPM using a vertical PPM advection scheme.

Subroutine Arguments

none

Local variables

j,k,q Grid and sediment class indeces.
delc6,delc,delc2,c6,dmc Variables used in the monotonisation.
xi Used to calculate SPM concentration.
a1,a2,a3 Used to calculate parabolas values in the PPM scheme.
sed,sedl,sedr Concentration at point and initial guess for right (down) and left (up)values.
dca,dc Difference between up and down concentrations and the average of that difference.
fc Sediment fluxes.
d2c,db Not used???

Global variables changed

spm

Logical units

none

Order of Things

  1. Set up array of water column values.
  2. Calculate parabolas intervals.
  3. Iitial guess at left and right values.
  4. Correct at and near surface and bed values.
  5. Monotonisation.
  6. Calculate fluxes.
  7. Update concentrations.

Calls

none

Called By

spmsubmodel

Options - Logical

none

Options - Compiler

none

Known Issues

none


subroutine spmsource

Description

Set the boundary conditions for terrestrial sources of SPM from Monthly data. The default set up is for the Holderness of cs3 grid model. The source strength is in Ktonnes/day.

Subroutine Arguments

none

Local variables

Ssource,Nsource,maxNsource Sediment source, number of source points and maximum number of source points
Isource,Jsource Grid indeces for the source points.
Ifrac Index for the sediment class.
k,kk,i,j,is,js Grid source and grid indices.
first Logical to fid if its the first time through.

Global variables changed

spm

Logical units

71 spmsource.dat Reads the source data

Order of Things

  1. Reads the smp land source data in ktonnes/day.
  2. Converts it to g/s
  3. Distribute data to all processors.
  4. Check for which month is the run.
  5. Check if the source grid poin is within the processor.
  6. Updates SPM concentration.

Calls

copy1di,copy2ds,copy2dr
monthfind

Called By

spmsubmodel

Options - Logical

first if true reads source data

Options - Compiler

none

Known Issues

none


subroutine outspm(lu)

Description

Writes SPM concentrations output.

Subroutine Arguments

lu

Local variables

i,itimt,j,kk,k Grid, time and SPM class indeces.
work2d2 Work variable used to pass data through processes.

Global variables changed

none

Logical units

lu

Order of Things

  1. Gathers data and writes it to lu

Calls

out2df2,out2d

Called By

data_out

Options - Logical

none

Options - Compiler

none

Known Issues

none


next up previous
Next: tidbndrp2.F Up: The Proudman Oceanographic Laboratory Previous: sigmaset.F
The AMMP Project 2005-04-20