Chapter 6: Global Fluxes and The Deep Circulation Heat Budget Conservation of Salt Oceanic Water...
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Transcript of Chapter 6: Global Fluxes and The Deep Circulation Heat Budget Conservation of Salt Oceanic Water...
Chapter 6: Global Fluxes and The Deep Circulation
Heat Budget
Conservation of Salt
Oceanic Water Masses
Oceanic Mixing Temperature - Salinity Diagrams
•The temperature and salinity of water in the ocean are determined while that water is at the surface.
•Temperature of surface water is determined by the relative sizes of the different terms in the oceanic heat budget equation.
•Salinity is determined by the balance between evaporation and precipitation and by the freezing and melting of ice.
NOTES
Qs + Qv = Qb + Qh + Qe + Qt
HEAT- Budget Equation
Qs = incoming short-wave radiation
Qv = heat advected into the region in currents
Qb = heat lost from the sea-surface by long-wave radiation
Qh = heat lost by conduction/convection
Qe = net amount of heat lost by evaporation
Qt = net amount of heat available to raise the temperature
Qs: Wm-2
The net radiation balance is largely controlled by variations in Qs
Net Radiation Balance (Qs – Qb)
Qb: depends on surface temperature, cloud cover and type, and water vapor content.
Generally (Qs – Qb > 0)
Qs + Qv = Qb + Qh + Qe + Qt
HEAT- Budget Equation
Qv = heat advected into the region in currents (includes vertical circulation (i.e. upwelling and downwelling currents)).
Qh, Qe
•depend upon the gradients of temperature and water content respectively, of the air above the sea-surface
•Generally represent a loss of heat from the sea
•Enhanced by increased atmospheric turbulence above the sea-surface.
•Difficult to estimate
•Qe is negative around the Grand Banks off Newfoundland where the cold Labrador Current promotes condensation of water vapour onto the sea-surface
SST: July and January
15oN – 15oS net heat gain
Net loss in winter hemisphere at higher latitudes
Qh greater role in NH winter cooling, cold dry continental air also enhances Qe
Sea ice reduces Qs but leaves Qb relatively unaffected so is maintained