Review of conservation equations State, Mass and Momentum
Equation of State (EOS-80) Determines water density from T, S, and P A through N are polynomials T is temperature in oC S salinity P pressure in bars K secant bulk modulus – measure of compresibility
Check values: A B C D T0 999.842594 8.24493E-1 -5.72466E-3 4.8314E-4 F G 19652.21 54.6746 7.944E-2 148.4206 -0.603459 1.6483E-2 -2.327105 1.09987E-2 -5.3009E-4 1.360477E-2 -6.1670E-5 -5.155288E-5 H I J 3.239908 2.2838E-3 1.91075E-4 1.43713E-3 -1.0981E-5 1.16092E-4 -1.6078E-6 -5.77905E-7 M N 8.50935E-5 -9.9348E-7 -6.12293E-6 2.0816E-8 5.2787E-8 9.1697E-10 Check values:
90 % of Ocean Water Greater influence of salinity on density Mean T & S for World Ocean Greater influence of salinity on density
Effects of Temperature and Salinity on Density Thermal Expansion Saline Contraction x 10-4 oC-1 x 10-4 S-1 Density changes by 0.2 kg/m3 for a T change of 1oC, and by 0.8 kg/m3 for a S change of 1.
Flux of mass out (kg/s) = , w , v Mass per area per time (kg/(m2 s)) Flux of mass in (kg/s) = Flux of mass out (kg/s) = Net Flux of mass in ‘x’ = Net Flux of mass in ‘y’ = Net Flux of mass in ‘z’ =
The change of mass per unit time going through the volume element is: And the change of mass per unit time per unit volume is: which is the same as: or
Boussinesq approximation This is the Continuity Equation or Equation of Conservation of Mass How valid is the Boussinesq approximation in the OCEAN? How would you determine that? 1 sigma-t throughout one day = 1 / (24*3600.) = 1.1510-5 But
z x Continuity Equation in Bulk Form:
Conservation of Salt: Conservation of Heat: Equation of State:
z Sb S0 x Continuity Equation in Bulk Form: Salt Conservation Equation in Bulk Form: VbSb = V0S0
Conservation of Momentum (Equations of Motion)
Pressure gradient + friction + tides + gravity + Coriolis Pressure gradient: Barotropic and Baroclinic Friction: Surface, bottom, internal Tides: Boundary condition Gravity: Only in the vertical Coriolis: Only in the horizontal REMEMBER, these are FORCES PER UNIT MASS
Pressure gradient + friction + tides + gravity + Coriolis Pressure gradient: Barotropic and Baroclinic Friction: Surface, bottom, internal Tides: Boundary condition Gravity: Only in the vertical Coriolis: Only in the horizontal REMEMBER, these are FORCES PER UNIT MASS
Hydrostatic Pressure Total Pressure Pressure gradient force per unit mass Barometric Barotropic Baroclinic Note that even if the density is constant with depth, the horizontal pressure gradient increases with depth if there is a horizontal density gradient
Pressure gradient + friction + tides + gravity + Coriolis Pressure gradient: Barotropic and Baroclinic Friction: Surface, bottom, internal Tides: Boundary condition Gravity: Only in the vertical Coriolis: Only in the horizontal REMEMBER, these are FORCES PER UNIT MASS
Friction @ surface: @ bottom: @ interior:
Pressure gradient + friction + tides + gravity + Coriolis Pressure gradient: Barotropic and Baroclinic Friction: Surface, bottom, internal Tides: Boundary condition Gravity: Only in the vertical Coriolis: Only in the horizontal REMEMBER, these are FORCES PER UNIT MASS
Gravity [0, 0, g] = [0, 0, 9.81] Coriolis [-fv, fu, 0]