Global Fluxes Of Heat And Freshwater

In this Volume, we have seen how heat is redistributed over the surface of the globe by winds in the atmosphere and by wind-driven surface currents and deep density-driven flow within the ocean. The simple plots showing heat transport in the atmosphere and ocean (Figure 1.5) show the end-result of very complicated processes, involving three dimensional flow of bodies of air and water of differing temperatures. Fluxes of heat and salt are intimately inter-related (Section 6.3), and the global...

Africa

Figure 5.19 (at Schematic diagram showing a disturbance of the upper ocean caused by an abrupt change irt the overlying wind field (b) Such a disturbance may he generated in the western Atlantic and travel eastwards as an eouatoiiai Kelvin wave at the eastern boundary, this splits info two coastal Kelvin waves, which contribute to seasonal upwellmg in the Gulf of Guinea fcf. Figure 5.9). As discussed in Section 5.1.1, the equatorial thermocline slopes up from the west and is nearesi to the...

Investigating The Ocean Through Computer M00elung

As mentioned earlier, the simple square oceans driven by simple wind fields, envisaged by Sverdrup, Stommel and Munk (Figures 4.10, 4.13 and 4.14) are representations or models of the real ocean. They are not attempts to replicate the real ocean in all its complexity, but experimental mathematical constructs intended to reveal the fundamental factors that determine the pattern of the global ocean circulation. Furthermore, the imaginary oceans they represent are essentially two dimensional, and...

The World Ocean Circulation Experiment

At the end of the 1980s, in an effort to address the lack of knowledge about the role of the ocean in the global climate system, the international oceanographic community launched the World Ocean Circulation Experiment (WOCE). In summary, the primary aim of WOCE was to develop the means to predict climate change. To this end. the following aspects of the world oceanic circulation were investigated more thoroughly than ever before 1 The large-scale fluxes of heat and freshwater, their...

Early Observations And Theories

European exploration of the eastern seaboard of the New World began in earnest during the sixteenth century. Coastal lands were investigated and much effort was put into the search for a North-West Passage through to the Pacific. The earliest surviving reference to the Gulf Stream was made by the Spaniard Ponce de Leon in 151His three ships sailed from Puerto Rico, crossed the Gull Stream with great difficulty north of what is now Cape Canaveral I in Florida), and then turned south. By I 19 the...

Southwest Monsoon

Indian Ocean Circulation

Figure 5.12 Surface currents in the northern Indian Ocean, as deduced from ships' drift data. The North-East Monsoon is most fully established from January to March ((a),(b)), and the South-West Monsoon is most fully established during July-September ((d),(e)). The thicknesses of the lines indicate the relative intensities of the flows. For example, current speeds in the Equatorial Jet ((c),(f)) may reach 1.0-1.3ms1, but are mostly 0.3-0.7ms 1. The South Equatorial Current (SEC) is spread over...

The Current System Of The Indian Ocean

As you might expect, the surface circulation of the northern Indian Ocean changes seasonally in response to the monsoons, but most resembles that of the other two oceans in the northern winter, during the North-East Monsoon (cf. Section 5.2.1). At this time of year, both a North and a South Equatorial Current are present, as well as an Equatorial Counter-Current (Figure 5.12(a).(bl). In the northern summer, by contrast, the flow in the North Equatorial Current reverses and combines with a...

The Heatbudget Equation

Ocean Circulation Distribution Heat

As discussed in Section 1.1. the Earth as a whole not only receives solar radiation, which is largely short-wave, but also re-emits long-wavelength radiation. This is because all bodies with a temperature above absolute zero emit radiation the higher the temperature of the body concerned, the greater the total amount of radiant energy emitted. In fact, the intensity ( ) of the radiation emitted increases in proportion to the fourth power of the absolute temperature (7) i.e. I oT4. This is known...

Summary Of Chapter

1 The global surface current pattern to some extent reflects the surface wind field, but ocean currents are constrained by continental boundaries and current systems are often characterized by gyral circulations. 2 Maps of wind and current flows of necessity represent average conditions only at any one time the actual flow at a given point might be markedly different from that shown. 3 The frictional force caused by the action of wind on the sea-surface is known as the wind stress. Its...

The Action Of Wind On Surface Waters

Figure 3.3 In a surface wave, water particles make orbits in the vertical plane. The particles advance slightly further in the crest (the top of the orbit) than they retreat in the trough (bottom of the orbit), so a small net forward motion (known as 'wave drift') results. In deep water, this motion may be of the order of several millimetres to several centimetres per second. When wind blows over the ocean, energy is transferred from the wind to the surface layers. Some of this energy is...

The Role Of Long Waves In Ocean Circulation

Surface Waves Ocean Circulation

The changes in the slopes of the sea-surface and thermocline along the Equator in the Indian Ocean, mentioned in Section 5.2.2, occur surprisingly fast. Exactly how fast the ocean can respond to seasonal changes in the wind has been studied in the simpler and steadier Atlantic, where the stress of the South-East Trade Winds across the equatorial ocean causes the sea-surface to slope up towards the west, and the thermocline to slope down (cf. Figure 5.3). In the Atlantic, the South-East Trades...

The Equatorial Undercurrent

The Equatorial Undercurrent (Figures 5.1(b) and 5.2) is a major feature of equatorial circulation. Such an undercurrent occurs in all three oceans, although it is only a seasonal feature in the Indian Ocean. Equatorial Undercurrents flow from west to east, below the direct influence of the wind, yet they arc w ind-driven. How can this be The effect of the wind is transmitted downwards to deeper layers via turbulence (eddy viscosity) and is mainly confined to the mixed surface layer above the...

The Global Thermohaline Conveyor

In the 1980s, Wallace Broecker suggested that the fluxes of heat and freshwater around the globe in ocean currents and water masses could be viewed as a kind of 'thermohaline conveyor belt' (Figure 6.41 ). This was not intended to be a realistic picture of warm and cold currents (although it is sometimes wrongly interpreted as such), but is a representation of the overall effect of warm and cold currents on the vertical circulation within the ocean. Its usefulness lies in the fact that because...