GEOL 1033 (Lesson 26) Ppt file 103-22 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: Salinity 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 Induction 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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