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CHAPTER 1
Physiography
I. OCEAN PROVINCES
A. Ocean Dimensions
There are five major oceans of the world. From largest to smallest, these include the Pacific, Atlantic, Indian, Southern, and Arctic oceans; together with their adjacent seas, they cover ~71% of the earth’s surface (~3.62 × 108 km2) and have a volume of ~1.34 × 109 km3. The surface area, volume, and average depth of the Pacific Ocean exceed all others, amounting to 1.66 × 108 km2, 6.96 × 108 km3, and 4.19 × 103 m, respectively. The Pacific Ocean constitutes more than 50% of the world’s ocean environment, and it occupies more than one-third of the earth’s surface. The Atlantic Ocean, with dimensions about half of those of the Pacific Ocean, has a surface area, volume, and depth of 8.41 × 107 km2, 3.23 × 108 km3, and 3.84 × 103 m, respectively. Somewhat smaller, the Indian Ocean has a surface area, volume, and depth of 7.34 × 107 km2, 2.84 × 108 km3, and 3.87 × 103 m, respectively. The Southern and Arctic Oceans are much smaller. The surface area, volume and depth of the Southern Ocean are 2.20 × 107 km2, 7.18 × 107 km3, and 3.270 × 103 m, respectively, and those of the Arctic Ocean are 1.56 × 107 km2, 1.88 × 107 km3, and 1.21 × 103 m, respectively.1,2,3,4,5
The Pacific Ocean comprises 50.1% of the world ocean and occupies more than one-third of the earth’s surface. By comparison, the Atlantic Ocean and Indian Ocean constitute 29.4% and 20.5% of the world ocean, respectively. The oceans range in width from ~5000 km (Atlantic) to ~17,000 km (Pacific).
About 75% of the ocean basins lies within the depth zone between ~3000 and 6000 m. The seas are much shallower, being ~1200 m deep or less. Some of the marginal seas are bounded by land or island chains (e.g., Caribbean Sea, Mediterranean Sea, and Sea of Japan). Others not bounded by land are distinguished by local oceanographic characteristics (e.g., Labrador, Norwegian, and Tasman seas).1,2 Marginal seas can strongly influence temperature and salinity conditions of the major ocean basins. For example, the warm, saline waters of the Mediterranean Sea can be detected over thousands of kilometers at mid-depths in the Atlantic Ocean.
Temperature and salinity differences are evident in the major oceans. Excluding the Southern Ocean as a separate entity, the Pacific Ocean exhibits the lowest temperatures and salinities with mean values of 3.14°C and 34.6‰, respectively. In contrast, the highest mean temperature (3.99°C) and salinity (34.92‰) exists in the Atlantic Ocean despite its large volume of riverine inflow. This is particularly true in the North Atlantic, where the mean temperature (5.08°C) and salinity (35.09‰) exceed those of all other major ocean basins. The Indian Ocean has intermediate mean temperature (3.88°C) and salinity (34.78‰) values. The mean temperature of the oceans is 3.51°C, and the mean salinity is 34.7‰.
The landmasses and ocean waters are not evenly distri...
