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"As part of the SO GLOBEC field program, the Woods Hole Oceanographic Institution (WHOI) deployed an array of instrumented subsurface moorings near Marguerite Bay during March 2001- March 2002 and a second array during March 2002-March 2003 (Figure 1). The moored measurements included pressure, temperature, conductivity, velocity, acoustic backscatter, and ice thickness. To monitor surface forcing during the moored array observations, two automatic weather stations (AWSs) were deployed on islands in Marguerite Bay and time series of wind, air temperature, pressure, and relative humidity were collected from May 2001 through March 2003.
The primary goals of this effort were to measure the temporal and spatial variability of currents and physical and biological water properties in the study area on time scales from hours to seasonal, improve our description and understanding of the regional general circulation, and identify and describe those physical processes that make this region well suited for krill production and survival." [from technical report WHOI-2005-07.pdf (10.2 MB)]
See WHOI-2005-07.pdf (10.2 MB)]
Rotation angle (rotangle): The basic coordinate system is x(east) and y (north); the x and y velocity components are u and v. for some analysis, the coordinate and velocity are rotated into a local isobath coordinate system, where xr and yr are the rotated coordinates and ur and vr are the rotated velocity components. rotangle is the angle that the rotated xr and ur point in, measured in degrees counterclockwise from east. In the A1 case, rotangle = -152 degrees. Thus, the xr axis has been rotated 152 degrees clockwise (due to the negative sign on rotangle) from x (east). The governing complex equation (as it is written in matlab) is:
ur + i*vr = exp(i*pi*rotangle/180)*(u + i*v) where i = sqrt(-1).
RDI ADCP (WorkHorse), sample baud rate=1800; RDI ADCP (BroadBand), sample baud rate=3600
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).
Temperature and conductivity measurements, 150s sample rate.
The Sea-Bird MicroCAT CTD unit is a high-accuracy conductivity and temperature recorder based on the Sea-Bird SBE 37 MicroCAT series of products. It can be configured with optional pressure sensor, internal batteries, memory, built-in Inductive Modem, integral Pump, and/or SBE-43 Integrated Dissolved Oxygen sensor. Constructed of titanium and other non-corroding materials for long life with minimal maintenance, the MicroCAT is designed for long duration on moorings.
In a typical mooring, a modem module housed in the buoy communicates with underwater instruments and is interfaced to a computer or data logger via serial port. The computer or data logger is programmed to poll each instrument on the mooring for its data, and send the data to a telemetry transmitter (satellite link, cell phone, RF modem, etc.). The MicroCAT saves data in memory for upload after recovery, providing a data backup if real-time telemetry is interrupted.
temperature, conductivity & pressure measurements, 900s sample rate.
The CTD SEACAT recorder is an instrument package manufactured by Sea-Bird Electronics. The first Sea-Bird SEACAT Recorder was the original SBE 16 SEACAT developed in 1987. There are several model numbers including the SBE 16plus (SEACAT C-T Recorder (P optional))and the SBE 19 (SBE 19plus SEACAT Profiler measures conductivity, temperature, and pressure (depth)). More information from Sea-Bird Electronics.
ASL Environmental Sciences ice-profiling sonars (IPSs)deployed at the top of A2 and B2 measured the acoustic range to the surface (the sea surface or ice bottom when present) every 2 secs and water temperature, pressure, and x- and y-tilt every 120 secs.
The ASL Environmental Sciences (e.g. IPS4 or IPS5) ice profiler is an upward looking sonar device deployed on a mooring for measuring ice keel drafts. The distance between the instrument and the bottom of the ice is measured by sonar at an operating frequency of 420 kHz with a beam width of 1.8 degrees and sampling rate of up to 2Hz. Water depth is measured by a pressure sensor and ice draft is calculated by the difference.
The Sea-Bird Electronics SBE 26 SEAGAUGE is a wave level and tide recorder with a pressure sensor, accurate clock, precision thermometer and optional SBE 4M conductivity sensor. Pressure data are integrated to give sea level or are burst recorded at rates up to 4 Hz to characterize waves. The standard pressure sensor is a 20 meter (45 psia) Quartzonix, with a temperature-compensated quartz element. Optionally, the SBE 26 can be configured with a Paroscientific Digiquartz pressure sensor with a temperature-compensated quartz element in 13 ranges, from 1 to 6800 meters (15 to 10,000 psia). more information from Sea-Bird Electronics
900s sample rate
Vector Averaging Current Meter
starting year of mooring deployment
latitude, negative = South
longitude, negative = West
depth of instrument, negative = height above sea surf.
time GMT in hours (0-23)
time GMT in minutes (0-59)
day of month GMT (1-31)
month of year GMT (1-12)
year
conductivity
potential density
salinity, PSS78
water temperature, IPTS68
mooring identification
water depth
GMT day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon).
water density
The angle that the rotated coordinates, xr, and the rotated velocity components, ur, point - measured in degrees counterclockwise from east (see more in Acquisition section, above)
Julian day as a decimal, for reference: Julian day 2440000 begins at 0000 hours, May 23, 1968
seconds
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