Ocean Introduction
Science of voyages Applied marine Science began in Alexandria—third century B.C. Eratosthenes—second librarian was first to calculate the circumference of the world. Invented celestial navigation Cartography flourished
The dark ages was a time of no real scientific development The Chinese and Arabs made the first compass for navigation
The Polynesians were famous for their seagoing voyages but resource depletion became their downfall. They were some of the most skilled navigators fig 1.1
Vikings The Dark Ages were spotted with raids by Vikings in Europe. Europeans finally banded together to stop them and this may have brought about the renaissance
Chinese Admiral Zheng had the largest fleet of ships ever assembled in 1405 Explored the Indian Ocean, Indonesia, and tip of Africa and Antarctica The primary purpose was to show the wealth of the new dynasty of the time.
They gave away things they did not pillage like the Vikings and the Spanish. They wanted to show they were the only truly civilized people on earth. Invented central rudder, watertight compartments, multiple masts and sophisticated sails.
The chinese abndiopnded ocean exploration in The cost was to high.
The age of Discovery Prince Henry the Navigator strong supporter of sea voyages (gave them compasses) Christopher Columbus Ferdinand Magellan James Cook John Harrison Sir John Ross
Lt. Charles Wilkes Matthew Maury Charles Darwin Alfred Thayer Mahan Fridtjof Nansen Robert E. Peary Captain William Anderson
SCICEX Meteor Expedition Tpoex/Poseiden JAMSTEC Jason 1 SEASTAR Aqua GPS
II. Word oceans - Covers 70.8% of the surface of the Earth to a mean depth of 4km A. Major ocean basins (fig 2.1) 1. Pacific - almost as large as all others combined, but shrinking 2. Atlantic - growing 3. Indian - strongest winds, largest waves 4. Arctic - ice covered year round 5. Southern ocean - sum of all other ocean basins surrounding Antarctica - not really an ocean (fig. 1.2) 6. Seas/gulfs
B. Oceanic climactic regions (figs) - regional winds and precipitation (global climate) due to intertropical convergence and Hadley cells, which I will not cover in detail in this course, but you should be familiar with the regional winds and precipitation levels/salinity)
1. Equatorial - 0° to 10° N/S of equator a. Doldrums b. Low salinity waters due to high precipitation
2. Tropical - 10° N/S to 23°N/S a. Tradewinds - NE in north, SE in south b. Hurricanes/Typhoons (Atlantic/Pacific) severe seasonal cyclonic storms that transfer lots of heat and precipitation into the subtropical regions c. Monsoons - seasonal wind shifts and heavy rains in Indian Ocean (not cyclonic, active for a whole season)
3. Subtropical - 23° N/S of equator to approx 40° N/S a. Dry, high pressure, little winds b. High salinity waters
4. Temperate - 40° N/S - 60° N/S a. Westerly winds(SW in N and NW in S)
5. Subpolar - 60° N/S -80° N/S a. Winter - ice, summer - open water b. Surface temps rarely above 5°C c. High salinity - due to freezing - salt leaves water as it freezes, being forced in to the surrounding water making it more saline.
6. Polar >80° N/S a. Ice covered b. Lightless polar winters - due to 23° axial tilt of Earth (also reason for seasons) - show sun clock images i. Arctic - no sunlight Dec - Feb ii. Antarctic - no sunlight Jun - Aug
C. Seasonality of oceanic temperatures - figs - ocean temperatures vary seasonally, as do air temperatures, due to the axial tilt of the earth - you can see the shift in warm temps from sorth of the equator during June to south of it in December
C. Seasonality of oceanic temperatures- ocean temperatures vary seasonally, as do air temperatures, due to the axial tilt of the earth - you can see the shift in warm temps from south of the equator during June to south of it in December (fig - surface temp images from internet) a. Warm water from equator N and S (Gulf stream) - effects climate of Northern Europe b. Cold water return - deep currents/upwelling - effects climate of shorelines, e.g. California (dry) and West. S.A.