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The physical setting

The physical setting. Latitude. 1 ° latitude ~ 111 km. Rp=6356.7497 km. 1 ° longitude ~ 111 cos j km. 1 nautical mile = the length of an arc (1 minute of a great circle of earth). Re=6378.1349 km. Nautical miles and meters are connected historically to the size of Earth.

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The physical setting

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  1. The physical setting Latitude 1° latitude ~ 111 km Rp=6356.7497 km 1° longitude ~ 111 cos j km 1 nautical mile = the length of an arc (1 minute of a great circle of earth) Re=6378.1349 km Nautical miles and meters are connected historically to the size of Earth. The meter was originally intended to be one tenmillionth the distance from the Equator to the pole along the Paris meridian.

  2. The polar circumference of Earth is approximately 2πRp= 40075 km. ‘meter’=(40075x1000) / 4 x 1/10,000,000 = 1.0019 ‘nautical mile’=2πRp / (360x60) = 1.855 km the international nautical mile: 1 NM ≡ 1.852 km. Equal distance Not equal distance

  3. Oceans and Seas There are only three oceans by international definition: the Atlantic, Pacific, and Indian Oceans (International Hydrographic Bureau, 1953). Atlantic Ocean Pacific Ocean Indian Ocean

  4. Download global bathymetric data (ETOPO5, 2 & 1) at http://www.ngdc.noaa.gov/mgg/global/etopo2.html Global bathymetric chart (ETOPO2v2) Depth measurement using single-beam sonar Depth measurement using multi-beam sonar

  5. Sea floor features Cross-section of the South Atlantic along 25°S 180:1 30:1 Principal features of the sea floor See P. 26-27

  6. Sea floor structure 大陸棚 深度<200m,坡度約1/1000 寬窄不一有1公里亦有千餘公里者 大陸斜坡 深度200~4000m,坡度約7/100 一般寬度不及20公里 大陸棚緣 大陸隆堆 深度>4000m,坡度約1/125~250 最大寬度約數百公里 深海平原 深度4000~6000m,地形平坦 海溝 深度>6000m,板塊隱沒帶

  7. Sulfide (HS-) Chloride (Cl-) etc. Sodium (Na-) Potassium (Kl+) Magnesium (Mg++) etc. Sulfide (HS-) Chloride (Cl-) etc. Seawater

  8. Vertical structure of T & S 表層(~500m) General Properties of Seawater 躍層 (500~1000m) 深層 (1000m~) Light penetration in seawater 溫躍層 密躍層 鹽躍層 密躍層 藍光穿透最深

  9. Practical Salinity Scale of 1978 By the early 1970s, accurate conductivity meters could be deployed from ships to measure conductivity at depth. The need to re-evaluate the salinity scale led the Joint Panel to recommend in 1978 that salinity be defined using only conductivity, breaking the link with chlorinity. All water samples with the same conductivity ratio have the same salinity. The Practical Salinity Scale of 1978 is now the official definition: S = 0.0080 − 0.1692RT1/2+ 25.3851RT+ 14.0941RT3/2− 7.0261RT2+ 2.7081RT5/2+ΔS RT= C(S, T, 0)/C(KCl, T, 0) ΔS =[(T − 15)/(1 + 0.0162 (T − 15))]+ 0.0005 − 0.0056R1/2T− 0.0066RT − 0.0375RT3/2+ 0.636RT2− 0.0144RT5/2 2 ≤ S ≤ 42 where C(S, T, 0) is the conductivity of the sea-water sample at temperature T and standard atmospheric pressure, and C(KCl, T, 0) is the conductivity of the standard potassium chloride (KCl) solution at temperature T and standard atmospheric pressure. The standard KCl solution contains a mass of 32.4356 grams of KCl in a mass of 1.000000 kg of solution.

  10. The most recent scale is the International Temperature Scale of 1990 (ITS-90). It differs slightly from the International Practical Temperature Scale of 1968 IPTS-68. At 0oC they are the same, and above 0oC ITS-90 is slightly cooler. t90− t68 = −0.002 at 10oC, −0.005 at 20oC, −0.007 at 30oC and −0.010 at 40oC. International System of Units (abbreviated SI) SI base units

  11. Standard prefixes for the SI units of measure

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