Oceanic Circulation and Water Movement

Abstract

Energy from the sun in the form of electromagnetic radiation reaches the earth as shortwave radiation in the ultraviolet, visible and infrared, with a peak at a wavelength of 0.5 μm (Figure 2.1). Assuming no atmosphere, sea and land surfaces exposed perpendicularly to the sun’s energy would receive about 1.36 kW m⁻² (this figure is called the solar constant). They receive much less because scattering, absorption, and reflection takes place in the atmosphere (Table 2.1). On clear days 80% reaches the ocean’s surface, but on cloudy days the figure is only 25%. At a water depth of 10 metres these percentages are reduced to 8% and 2.5% in oceanic waters and 0.4% and 0.125% in coastal waters.