The Global Heat Budget

• Air-sea exchanges of heat (& freshwater) create

deep water masses & drive the conveyor belt

• Heat source into the ocean is solar radiation

• There are several heat loss terms

latent, conduction, longwave radiation, reflected

solar

• Ocean circulation moves heat (advection)

Solar Radiation

Solar Radiation

The Heat Budget

Total heat flux (Qt) = Solar radiation (Qs)

- Latent heat loss (Qe)

- Conductive heat loss (Qh)

- Longwave radiation (Qb)

Qt = Qs - Qe - Qh - Qb

Heat Loss Terms

• Latent heat flux (Qe)

– Energy required to evaporate water

– Most important in tropics & midlatitudes

• Conductive (or sensible) heat flux (Qh)

– Loss to turbulent exchange with atmosphere

–Typically small

• Longwave radiation (Qb)

– Net thermal IR emission from ocean

Global Heat Budget

Net Solar Radiation

Typical Jan

Tropics 200 W/m2

Mid-latitudes 100 W/m2

High-latitude ~10 W/m2

Latent Heat Loss

Typical Jan

Tropics 120 W/m2

Mid-latitudes 100 W/m2

High-latitude ~20 W/m2

Conductive Heat Loss

Typical Jan

Tropics 0-10 W/m2

Mid-latitudes 0-40 W/m2

High-latitude 0-30 W/m2

Net Longwave Radiation

Typical Jan

Tropics 40-50 W/m2

Mid-latitudes 60-70 W/m2

High-latitude 30-50 W/m2

Total Heat Flux

Typical Jan

Cool NH

Heat - SH

WBC’s -200 W/m2

SH Subtropics 70 W/m2

NH Subtropics > -80 W/m2

Total Heat Flux

Typical July

Heat NH

Cool SH

NH Subtropics 100 W/m2

SH Subtropics -40 W/m2

Global Heat Budget

Global Heat Transport

Global Heat Transport

1015 W = 1 Petawatt

Hydrographic Inverse Models

• WOCE hydrographic sections are used to estimate global circulation & material transport

• Mass, heat, salt & other properties are conserved

• Air-sea exchanges & removal processes are considered

• Provides estimates of basin scale circulation, heat & freshwater transports

Global Heat Transport

Global Heat Transport

Global Heat Transport

The Global Heat Budget

• Heat source into the ocean is solar radiation

• There are several heat loss terms

latent, conduction, longwave radiation, reflected

solar

• Ocean circulation moves heat (advection)

• Large scale heat budget can be closed by

analyzing hydrographic sections