Salt mass conservation
With salt mass fraction s, conservation is ∂(ρs)/∂t+∇·(ρsu+J_s)=r_s.
Key knowledge
With salt mass fraction s, conservation is ∂(ρs)/∂t+∇·(ρsu+J_s)=r_s. J_s is nonadvective salt-mass flux and r_s a salt source per volume per time. In the source-free nondiffusive model, mass conservation implies Ds/Dt=0. Evaporation can change a parcel or reservoir's salt fraction by removing water even when it removes negligible salt.
Values and equations
∂(ρs)/∂t+∇·(ρsu+J_s)=r_s
- ρ
- solution mass density kg m⁻³
- s
- salt mass fraction kg kg⁻¹
- u
- velocity m s⁻¹
- J_s
- nonadvective salt-mass flux kg m⁻² s⁻¹
- r_s
- volumetric salt-mass source kg m⁻³ s⁻¹
Conditions and scope
- s is salt mass per total solution mass,not numerical practical salinity treated as an exact mass fraction. All sources and boundary fluxes need the same convention.
- Freshwater input, sea-ice formation/melt, sediment or chemical exchange and molecular/turbulent transport require corresponding terms. A spatially uniform scalar diffusivity is an additional closure, not the conservation law itself.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual mass/salt setup equations9.2–9.3 and source-free material limit9.12. J_s/r_s are an explicitly disclosed conservative extension by salt inventory bookkeeping; no unread seawater standard or practical-salinity-to-mass conversion adopted.
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Entry details
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