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Unformatted text preview: Marine Instruments 1. 4 major groups: o Drop overboard XBT- expendable bathy-thermographs: gives a temp. profile with depth CTD- conductivity (salinity), temp., depth Give information at one spot = profiles String profiles together to get a cross-section Stationary in-situ instruments Held at a fixed position in the water = Eularian approach Ex.: let a current flow past a fixed current meter (ADCP) Can use a buoy system and string instruments together Can get time series data for specific locations Floaters/drifters Lagrangian approach 2 types: Surface floats Composed of a float and sub-surface drogue Isopycnal float Sind down to a certain density and travel with the current Designed to go to the surface and transmit data Don't always have to use instruments-can use anything that floats Marine Instruments o Those carried on satellites Give us a synoptic view of the ocean-see the whole thing at one time Only measure the top millimeter of ocean 2 types of satellites: Geostationary-fixed above the equator and orbit earth every 24 hours Always see the same spot Low resolution, can get time series loops Polar orbit-make an orbit around earth every 90 minutes Get a different look with each path Very detailed, high resolution, can get time series loops What goes on satellites: : Radiometer : measures emitted infrared radiation; passive; info. is then converted to temp. by Q=cT Also measures reflected visible radiation (off of clouds) Measure coming off of surface: track chlorophyll across oceans Scatterometers : active; measures distortion of ping energy returning from ocean surface Related to "roughness" of ocean; can infer wind speed; can measure wave heights : Altimeters : active; uses energy ping to measure distance of satellite from ocean surface Measures sea height= dynamic topography Track El Nino because of thermal expansion of warm water What is a Wave? o Transfers a disturbance (energy) from one point of a material (water) to another o No net overall motion to the material o Energy is transported through the water without any transport of the water itself o They have constant speed and constant period o The waves we see rushing up on the beach are not really waves- they are breakers Wave Characteristics: wave number (k)= 2 /L ~ 1/L wave frequency (...
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This note was uploaded on 04/13/2008 for the course MSCI 304 taught by Professor Gilman during the Spring '08 term at Coastal Carolina University.
- Spring '08