Advanced Oceanography Ocean Circulation - Chapter 1 A Review Circulation in both the oceans and the atmosphere is driven by energy from the Sun and modified by the Earth’s Rotation The oceans are mechanically driven by the atmosphere – winds. The oceans are thermally driven by the atmosphere by inducing changes in temperature and salinity (precipitation and evaporation, review latent and sensible heat fluxes)

Ocean current system involves both wind driven surface currents and density-driven (thermohaline) deep circulation.

Wind bands – Three convection cells in each hemisphere Trade winds = NE (30°N to 0°) and SE (30°S to 0°) Westerlies = 60°N to 30°N and 60°S to 30°S Polar easterlies = 90°N to 60°N and 90°S to 60°S Low pressure at 0°, 60°N, and 60°S Low pressure, ascending air, clouds, increased precipitation High pressure at 30°N, 30°S, 90°N, and 90°S High pressure, descending air, clear skies, low precipitation Look at the winds:

Now look at the currents:

Review the Coriolis Force Air and water masses moving over the surface of the Earth are subject to the Coriolis force. The Coriolis force acts at right angles to the direction of motion, is zero at the Equator and increases to a maximum at the poles.

Review The Radiation Balance The radiation balance of the Earth-ocean- atmosphere system is positive at low latitudes and negative at high latitudes.

Poleward Heat Transport: Upper Atm. Wind systems in the atmosphere and current systems in the ocean redistribute this heat around the planet.

Fig. 6-16, p. 168 Sea-surface average salinities in parts per thousand (‰). Sea-surface temperatures during Northern Hemisphere summer

Fig. 6-14, p. 167 Tropic of Cancer Equator Tropic of Capricorn Salinity Temperature Latitude North South