Science Modules / Tracers

Modellers can use the aed_tracer to simulate a particulate tracer that can be set to also settle and decay. In addition to suspended sediment simulated in this way, the aed_totals module has an option to assign any number of FABM variables (including non-AED variables) to contribute to a turbidity, subject to a transformation coefficient.

Modellers can also use this module to simulate the water retention time. In this case the water retention time is treated as a tracer with a growth rate of 1 with time after enterting the water body, and being mixed and transported with water.

aed2_tracer :

The AED2 module tracer contains equations that describe a soluble or particle tracer, including decay, sediment interaction, and & resupension and settling

Variable Summary & Setup Options

The following state variables are core or optional STATE variables within aed2_tracer

Variable Name Description Units Variable Type Core/Optional
WQ_TRC_SS1 suspended solide tracer mmol m^{-3} pelagic core
WQ_TRC_RET water retention time seconds pelagic core

The following state variables are core or optional DIAGNOSTIC variables within aed2_oxygen

Variable Name Description Units Variable Type Core/Optional
TRC_SS1_VVEL suspended solid vertical velocity m/s pelagic diagnostic core
TRC_TAU dynamic bottom drag N/m^2 pelagic diagnostic core
TRC_FS sediment fraction of sed size % pelagic diagnostic core
TRC_RESUS resuspension rate g/(m^2*s) pelagic diagnostic core

The following parameters and configuration variables are available to be set via the nml module block:

Parameter Name Description Units Parameter Type Default Typical Range Comment
retention_time activate the retention time tracer - T/F .false. .true./.false.
num_tracers number of tracers to model integer 0.0 0-10
decay list of decay rate for the tracers /day float 0.0 -100-100
settling list of settling rate for the tracers m/s float 0 0-100
fsed list of sedimentation fluxes for the tracers /m^2/s float - -

An example nml block for the tracer module is shown below:

&aed2_tracer retention_time = .true. num_tracers = 2 decay = 0,0 !, 0, 0, ... settling = -0.03,-0.001 !, 0, 0, .... fsed = 0,0 !, 0, 0, ... Ke_ss = 0.06,0.063 !, 0.02, 0.02 resuspension = 0. !epsilon = 0.02 !, 0.02, 0.02 !tau_0 = 0.01 !, 0.01, 0.01 !tau_r = 1.0 !, 1.0, 1.0 /


Example 1: Simulated water retention time in Peel-Harvey Estuary in scenarios of (left) Dawseville Channel closed; (middle) normal conditions; and (right) Future climate change.

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