Relaxing the flux tolerance check for an individual box
There are times (e.g. during an extreme event, which might be implemented for a specific scenario, or if including restocking/replanting of seagrass for example) when the flux of a variable can legitimately be at a level that would breach the flux tolerance checks in place to ensure numerical stability (as conditioned by RelTol set in the biology.prm file). To allow for this there is a property per box in the BGM file, box#.relax_tol , which is typically set to 0 unless absolutely required.
For example
# Data for box number 0 ## user defined box number identifier
box0.label Box0 ##users reference box name, e.g. Box0 or Sydney Harbour
box0.inside 4043667.571 1150676.493 ## midpoint of polygon
box0.nconn 5 ## number of faces shared with other dynamic boxes
box0.iface 1 10 11 13 17 ## id numbers of shared faces, each face has a unique id
box0.ibox 0 2 2 2 2 ## box that each shared face corresponds to
box0.botz -370 ## maximum depth of the polygon in the real ecosystem
box0.area 3261982282 ## area of the box, m 2
box0.vertmix 0.000001 ## vertical mixing scalar for the polygon
box0.horizmix 1 ## horizontal transport scalar for the polygon
box0.relax_tol 0 ## whether relaxing flux tolerance for this box
box0.vert 4005591.597 1198429.099 ## List of vertices (x,y) in clockwise or counter clockwise order
box0.vert 3998613.455 1174049.433
box0.vert 4065533.389 1102640.49
box0.vert 4095090.658 1128446.461
box0.vert 4095245.855 1128504.676
box0.vert 4005591.597 1198429.099