41 terms

Unit 1: Geography, History, and Navigation


Terms in this set (...)

60 nm
- Throw rope tied at increments with weight at the end (called sounding) into the water → use wire attached to winch with counter or other device that indicated length of wire deployed
- Could learn about type of bottom by applying grease to bottom of weight
- Numerous difficulties include drifting if not anchored (wind and current)
- SOund NAvigation and Ranging
- Pulse of sound is transmitted → travels to bottom → reflected back and returns to recorder
- Time = depth
Fathometer (echo sounder)
- Sonar device
- Measures depth directly under the vessel → makes continuous readings that are recorded
- As the vessel moves it produces a vistal profile
- Result: echogram or sonography
- Limitation: beams emitted at a wide angle → measured depth is less than actual depth
Wide Area Sonar
- Multibeam or swath sonar (16 or more individual sonar beams broadcast from a ship)
- Sidescan sonar (2 wide-angle beams are broadcast from a submerged device ("fish") towed behind vessel → computer analyzes returning echoes)
- Use RADAR (RAdio Detection And Ranging)
- Radio signal sent from satellite → bounces off sea surface → returns to receiver
- Modern method for position determination for mapping
- Older method utilizing radio signals from two-land based stations
- Modern method for position determination for mapping
- Older method that measured distance and bearings to landmarks
- Modern method for position determination for mapping
- Uses signals emitted by satellites to determine position with a high degree of accuracy
Acoustic Current Meters
- Can infer direction and speed by Doppler Effect (shift)
- Advantages: convenience, low cost (usually)
- Disadvantages: limited depths, time underwater, personal risk
Manned Submersibles
- Advantages: long bottom times, deep depths, can carry lots of equipment easily
- Disadvantage: very expensive
Remotely Operated Vehicles (ROV)
- Advantages: cheaper to operate and easier to deploy than Manned Submersibles
- Limitations: can do less tasks than Manned Submersibles (no people inside of it)
Autonomous Underwater Vehicles (AUV)
- Still under development (limited use)
- Difficulties: control of vehicle, no hardware connection to surface (vessel), must have its own power source
Satellites (uses)
- Surface water temperatures (sea surface height)
- Weather (cloud patterns) and waves
- Suspended phytoplankton (chlorophyll) and sediments
- Ice
- Surface currents
Law of the Sea
- Territorial seas (complete control) extending 12 nm from coastlines
- Exclusive Economic Zones (control of resources) extending 200 nm or to the edge of the continental shelf
- High seas areas are outside of EEZs are ideally the common heritage of all nations → rules governing exploration of resources in these areas are complex and not universally accepted
Austronesian speakers and Polynesians
- Located in the Pacific
- Long range (200+ nm), open ocean voyages by 3000 BCE
- Evolution of long range no navigation journeying
- 3000 BCE
- Centered in Greece
- Used boats extensively for transportation, trade, defense, and conquest
- 1100-850 BCE
- Major sea power throughout the Mediterranean
- 450 BCE-150 AD
- Herodotus
- Pytheas
- Erathosthenes
- Ptolemy
- Constructed map of Mediterranean region
- 350-300 BCE
- Developed methods for estimating latitude
- 276-192 BCE
- Calculated circumference of earth as 25,000 statute miles (used the sun)
- 127-151 AD
- Produced first map of the known world → his maps were inaccurate with regard to longitude (used in Columbus's time)
- Developed trade routes in Indian Ocean
- 700-1000 AD
- Sailed to Iceland, Greenland, and NE North America
- Magnetic compass in use by the 13th century → probably from Asia
Europeans during Age of Discovery
- 15-16th century
- Vasco de Gama
- Christopher Colombus
- Amerigo Vesoucci
- Vasco de Balboa
- Ferdinand Magellan
- Francis Drake
- James Cook
Vasco de Gama
- Sailed around Cape of Good Hope
Christopher Colombus
- 4 voyages to Caribbean Islands
Amerigo Vesoucci
- Explored 6000 miles of the South American coast
Vasco de Balboa
- Discovered the Pacific Ocean by crossing Isthmus of Panama
Ferdinand Magellan
- Circumnavigated the globe
- Established the length of a degree of latitude → measured the circumference of the earth
Francis Drake
- Circumnavigated the globe while plundering Spanish and Portuguese
James Cook
- 1768-1779
- Founder of oceanographic science
- 3 Pacific voyages
- First to carry clock to establish longitudes
- Charted and described unknown geographic regions, documented marine life, conducted accurate soundings to 1200 feet, measured winds, currents and water temperatures
The Challenger Expedition
- 1872-1876
- First expedition designed for oceanography
- Naval ship refitted with laboratories, winches, oceanographic equipment, 144 miles of sounding ropes
Matthew Maury
- 1806-1873
- Father of physical oceanography
- Compiled very large bathymetric charts
- Late 1800's-early 1900's
- Froze boat in arctic ice to test hypothesis of Artic ocean currents → drilled holes through ice and documented ocean temperatures, plankton blooms
John Harrison
- Built clocks in the 1700's to figure out how to measure longitude at sea
- H4 → 4th clock (small, watch-type device) won the longitude prize
- Created in the mid 1700's
- Proving voyage: Europe to West Indies
- Polynesian islands settled from the South American side (east) or Southeast Asian side (west)
- South American side (east) - trade winds would push them that direction
- Southeast Asian side (west) - language, trade winds flip once a year for a little while, ceramics, animals, plants