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Brief Description: ADCP data from the Long-Term Observation Program (LTOP) NH10 Mooring
A long-term mooring site on the Oregon shelf (44.6467N -124.3067E) was established in August 1997 and maintained with few gaps through December 2004 with U.S. GLOBEC funding. The mooring is at 81 m water depth, near the historical Newport Hydrographic Line. The nearest standard NH line station is NH10 (10 nautical miles off shore), so this mooring is referred to as Mooring NH10.
Upward looking acoustic Doppler current profilers have been used to measure vertical profiles of water velocity (insert actual sample interval here) at 2 or 4 m vertical intervals depending on instrument. The mooring is serviced in spring and fall: winter deployments generally use a Sontek 250 kHz profiler with 4 m vertical resolution; summer deployments use a Sontek 500 kHz profiler with 2 m resolution. There are a few data gaps.
Currents are processed using a cosine-Lanczos filter with a 40-hr half-power point. Six-hourly data included here are Eastward (u) and Northward (v) velocities in cm/s interpolated to 2 m depth bins.
The data were collected by Mike Kosro, 104 COAS Admin Bldg, COAS, Oregon State University, Corvallis, OR 97331-5503 (firstname.lastname@example.org; Phone: 541-737-3079).
For further details about sampling/processing, see:
Kosro, M. 2003. Enhanced southward flow over the Oregon shelf in 2002: A conduit for subarctic water. Geophysical Research Letters, 30 (15), 8023, doi:10.1029/2003GL017436
Last modified: March 26, 2006
The ADCP measures water currents with sound, using a principle of sound waves called the Doppler effect. A sound wave has a higher frequency, or pitch, when it moves to you than when it moves away. You hear the Doppler effect in action when a car speeds past with a characteristic building of sound that fades when the car passes.
The ADCP works by transmitting "pings" of sound at a constant frequency into the water. (The pings are so highly pitched that humans and even dolphins can't hear them.) As the sound waves travel, they ricochet off particles suspended in the moving water, and reflect back to the instrument. Due to the Doppler effect, sound waves bounced back from a particle moving away from the profiler have a slightly lowered frequency when they return. Particles moving toward the instrument send back higher frequency waves. The difference in frequency between the waves the profiler sends out and the waves it receives is called the Doppler shift. The instrument uses this shift to calculate how fast the particle and the water around it are moving.
Sound waves that hit particles far from the profiler take longer to come back than waves that strike close by. By measuring the time it takes for the waves to bounce back and the Doppler shift, the profiler can measure current speed at many different depths with each series of pings. (More from WHOI instruments listing).
Upward looking acoustic Doppler current profilers have been used to measure vertical profiles of water velocity (insert actual sample interval here) at 2 or 4 m vertical intervals depending on instrument. The mooring is serviced in spring and fall. winter deployments generally use a Sontek 250 kHz profiler with 4 m vertical resolution; summer deployments use a Sontek 500 kHz profiler with 2 m resolution.
Mooring ID (NH10 for this dataset).
Latitude in decimal degrees North
Longitude in decimal degrees East
Water depth in meters
Depth of velocities in meters
Julian day, where JD2440000 is 0000 hrs on 23 May 1968.
Day of Year, where 0.5 is 1200 hrs on 1 January.
Month in GMT.
Day of Month in GMT.
Time of Day in GMT (HHMM).
Eastward Velocity (cm/s; Positive East)
Northward Velocity (cm/s; Positive North)
©2008 Biological and Chemical Oceanography Data Management Office.
Funded by the U.S. National Science Foundation