MOdel Shopping Tool ( MOST )
"POCb budget module (big POC)" from PISCES v1 Equations
Same equation in other models :
Equation Description :
The budget of large POC is controlled by the fecal pellet production as a result of grazing on all phytoplankton groups and microzooplankton, mesozooplankton excretion and mortality, the mortality of non-calcifying nanophytoplankton and diatoms, loss of POC via vertical export and degradation.
The fate of mortality and aggregation of nanophytoplankton depends on the proportion of
the calcifying organisms (RCaCO3). We assume that 50% of the organic matter of the calcifiers is associated with the shell. Since calcite is significantly denser than organic matter, 50% of the dying calcfiers biomass is routed to the fast sinking particles. The same is assumed for the mortality of diatoms as a consequence of the denser density of biogenic silica.
PHI terms represent aggregation processes. In PISCES, differential sedimentation
and turbulence coagulation mechanisms are considered.
Parameters definition and values:
delta POC = 0.025 d-1 (POC degradation rate dependent on temperature and Q10=1.9);
lambda POC = POC degradation;
sigma = 0.3 (fecal pellets production);
epsilon = 0.5;
PHI = aggregation processes (see link below for values);
D = concentration of diatoms in micro mol C l-1;
e = 0.35 (zooplankton growth efficiency);
g = 4,0.7 d -1 (max grazing rate for micro, mesozooplankton);
K P , K D= 0.1 micro mol C l-1 (half-saturation constant for mortality for nano, diatoms);
mP = 0.01 d-1 (phytoplankton mortality rate);
N = phytoplqnkton groups (P or D) that zooplankton can graze on;
P = concentration of nanophytoplankton in micro mol C l-1;
r = 0.03,0.008 d-1 (excretion rate for micro, mesozooplankton);
RCaCO3 = proportion of calcifiers, 50% of the OM of calcifiers is assumed to be associated with the shell;
w POC = sinking speed of POC m d-1;
w P = 0.01 d-1 mol C-1 (quadratic mortality of phytoplankton);
