Biology 124 Online Project: Measurements: Currents

TOOLS OF THE OCEANOGRAPHER: Equipment: Measuring tools: Currents

B. Taking Measurements of the Marine Environment
1. Temperature • Standard Thermometer • Bucket Thermometer • Reversing Thermometer (for Nansen Bottle) • Bathythermograph (BT)	2. Salinity • Hydrometer (quick test type for aquariums) • Hydrometer Set • Chemical Test Kit (Knudsen) • Salinometer
3. Oxygen • Chemical Test Kit (Winkler Titration) • Dissolved Oxygen Probe	4. pH • pH test strips • Chemical Test Kit • pH meter
5. Visibility & Color • Secchi Disk (used by itself) • Forel/Ule Scale (used with the Secchi disk)	6. Other • There are chemical tests for numerous dissolved substances including Carbon Dioxide, Nitrogen, Phosphates, Ammonia, Lead, Copper and Manganese
7. Depth & Profile • Sounder (lead line) • Fathometer •Surveying Equipment	8. Currents • Current Meter • Dye • Drogues • Drift Bottles • Drift Cards

8. Currents

Current Meters

Measures:	Relative speed of water flow (current)
Operates:	At any depth by cable or line
Notes:	Other current meters are on top of the cupboards in lab, some have directional recorders as well

Dye for Currents

Measures:	To stain the water so that its movement (current) can be traced
Operates:	By pouring
Notes:	Nontoxic and biodegradable (is gone in about 20 minutes)

Drogues (bottom with weight, and surface with float)

Above picture: surface drogue (with float)

Above picture: bottom drogue (with weight)

Measures:	Currents over long distances
Operates:	By releasing many and hoping for recapture (only a few percent are ever recaptured)
Notes:	Like the note in a bottle, this can be a form of pollution and is not often used anymore. There are expensive buoys deployed for this purpose with the ability to send signals to satellites which can be recorded several times a day

Drift Bottles

Measures:	Currents
Operates:	By releasing a few
Notes:	May be affected by the wind but a quick and easy way to measure a current. May be considered pollution if not retrieved

Drift Cards

Measures:	Currents
Operates:	By releasing
Notes:	Weighted to stay just below the surface of the water May be considered pollution if not retrieved


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