G.3 Dry deposition of inorganic phosphorus

Dry deposition of inorganic phosphorus includes the delivery of adsorbed FRP to the water column from atmospheric dust fallout. A constant daily mass loading rate of adsorbed FRP is specifiable, and the WQ Module multiples this rate by model timestep and the global model surface area to compute the mass flux of adsorbed FRP (Equation (G.3)). This mass is added to the uppermost model layer cells and corresponding changes to ambient concentrations computed. Dry deposition is only included in calculations if adsorbed FRP is simulated.

\[\begin{equation} F_{atm-dry}^{FRPads} = R^{FRPads}_{atm-dry} \times \text{Timestep} \times \text{Global model area} \tag{G.3} \end{equation}\]

\(R^{FRPads}_{atm-dry}\) is the user specified rate of adsorbed FRP atmospheric fallout. One (constant) mass flux is applied globally. This dry deposition is only applied if FRP adsorption is simulated, and if this is the case, then this introduction of dry deposited FRP is assigned to the adsorbed FRP computed variable. If adsorbed FRP is not included in a simulation, then dry deposition of FRP will be ignored.

The total atmospheric depositional flux of inorganic phosphorus is as per Equation (G.4).

\[\begin{equation} \href{AppDiags.html#WQDiagDIPAtmFlx}{F_{atm-dip\langle computed \rangle}^{P}} = F_{atm-wet}^{FRP} + F_{atm-dry}^{FRPads} \tag{G.4} \end{equation}\]