physical oceanography. part 1: introduction, measurements, instruments, etc. geol 1033 (lesson 26)...
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PHYSICAL OCEANOGRAPHY.Part 1: Introduction, Measurements,
Instruments, etc.
GEOL 1033
(Lesson 26)
Ppt file 103-22
PHYSICAL OCEANOGRAPHERS• Interested in
– Heat exchange– Evaporation– Density– Temperature– Water movements: currents, waves, tides, etc.– Other physical properties of water
• Measures:– Temperature– Salinity– Density– Oxygen content– Pressure – Currents
Some Physical Oceanography Instruments
• Nansen bottle– For water sample collection
– Lowered on a cable
– Activate with a “messenger” (= a little weight that slides down the cable until it hits and triggers the bottle to take a sample.)
Some Physical Oceanography Instruments
• Nansen bottle Collecting water samples at some depth
Some Physical Oceanography Instruments
• Bathythermograph– BT = acronym
– Usually lowered on a cable
– Sensitive to
• Temperature and
• Water pressure, which is related to depth
– Measures any changes in temperature as depth increases
– XBT = acronym for “expendable” bathythermograph
• Dropped from – a moving boat or
– even from an airplane
• Radio sends data back to ship/plane
Some Physical Oceanography Instruments
• BT (bathythermograph)
• Graphic profile of temperature variation with depth inscribed on a black-coated glass slide
Some Physical Oceanography Instruments
• XBT =
Expendable BT• Can be attached
by a cable to a recorder on ship
• Depth can be calculated because of known rate of descent.
• Data is radioed back to an airplane that drops one
Some Physical Oceanography Instruments
• STD device– Electronic– Lowered on a cable– Measures while
being raised or lowered:
• Salinity
• Temperature
• Depth (by measuring associated pressure changes)
– Transmits data by cable back up to ship
Some Physical Oceanography Instruments
• Rosette, a STD device:– Collect many water samples
– Up to 10 x30 L Nansen bottles
– Can be triggered electronically
– Pinger used to locate depth (or depth can be determined by pressure changes)
– Can record other information at the same time:
• suspended particle matter
• oxygen
MEASURING CURRENTS
MEASURING CURRENTS
• Current meters– Mechanical
• A fan-like device (rotor) spins on a shaft of a generator
• Electrical output is calibrated to water speed
– Induction• Applies the principle
that salt water is a conductor, so as water flows through a coil of wire an electric current is generated that can be calibrated.
MEASURING CURRENTS
• Indirect methods of studying water currents:– Measure other water properties whose variations indicate
water movements
– Study:• Oxygen content
• Temperature
• Salinity
• Density
• Radioactive isotopes, e. g., 90Sr
• Distribution of warm- or cold- water organisms (Gulf Stream example)
• Imagery– Airplane = Aerial photographs, e. g., visible spectrum,
infrared, etc.
– Satellite = infrared, reflectivity, visible-light, radar, etc.
MEASURING CURRENTS
• Determining coastal surface ocean current systems using aerial photography
Satellite Remote Sensing of the Grand Banks • Renewed petroleum exploration in the 1980's inspired
greater oceanographic research 370 km Canadian exclusive fishing zone
SATELLITE IMAGERY TO MEASURE SURFACE TEMPERATURES
SATELLITE IMAGERY TO MEASURE SURFACE TEMPERATURES
• Calibrations permit mapping surface temperature variations
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