Statement_of_Need_-_ADCP.docx

Requisition#

US Geological Survey Woods Hole Coastal & Marine Science Center Marine Operations Facility (MOF) Falmouth, MA 02540

I. FUNCTIONAL REQUIREMENTS

The USGS Woods Hole Coastal and Marine Science Center (the Center) needs to acquire an Acoustic Doppler Current Profiler (ADCP) to be used in sediment transport studies in shallow estuaries and in the nearshore coastal zone. The ADCP will be used to measure currents and directional waves in shallow environments (1 to 5 meters), using existing low-profile bottom landing platforms. Primary considerations are small and low–profile form factor, both current profiling and wave burst sampling in same deployment, and capability of relatively long deployment duration using only internal batteries. These systems must include the following salient features and characteristics:

· Form Factor- The system is required to meet the following form-factor requirements:

· Side-looking (right-angle head) transducer arrangement to allow low-profile horizontal mount for upward or downward looking measurements.

· Overall length < 700mm (27.6”). Required to fit in existing deployment frames.

· Housing diameter < 100 mm (3.94”). Required to fit in existing deployment frames.

· Measurements - The system will be capable of making the following measurements:

· Profiling range for mean currents > 5 meters.

· Minimum Profiling cell size <=0.10 meters.

· Minimum blanking distance <= 0.2 meters.

· Maximum number of profiling cells >= 200.

· Measure 3D velocities in user selectable choice of coordinate system; 1) instrument (xyz), 2) east-north-up (enu), and 3) beam, on a deployment by deployment basis.

· Accuracy of velocity measurement at least <= 1% of measured value +/- 0.5cm/s.

· Max sampling rate >= 1 Hz for velocity profile measurement.

· Wave burst sampling capability of velocity and pressure data with max sampling rate >= 2 Hz.

· Integrated pressure sensor with 0 – 30 m range and max sample rate >= 2 Hz and synched with velocity measurements. Accuracy/resolution 0.5%/0.005% of full scale or better.

· Integrated compass and tilt sensor with accuracy/resolution at least 2o/0.1o for compass and 0.2o/0.1o for tilt.

· Ability to include optional High Resolution (pulse coherent) mode, which allows for sampling up to 8 Hz

· Data Logger- The system should include a data logger which can do the following:

· Memory should allow instrument to log, at minimum, data for profiled currents every 15 minutes and wave burst (1024 samples) every 30 minutes for >= 100 days.

· Memory capacity >=16GB and should be in the form of a removable memory card.

· Shall have real time clock with accuracy +/- 1 min/year or better.

· Power- The system must have its own internal power:

· Information about the type of battery, capacity, method and cost of replacement shall be provided.

· There shall be enough self-contained battery power to record a mean current profile every 15 minutes (120s avg) and a wave burst (512s duration) every 30 minutes for >= 100 days in a single deployment.

· The ability to accept additional power from an external source, for testing on shore, or as a way to extend in-situ deployments.

· Internal power shall be contained in the instrument housing capable of full depth rating of instrument.

· Software: Instrument shall be provided with software that allows for communication with the instrument with a Windows PC type computer for the purposes of planning of different scenarios for evaluation of deployment parameters and initiating a deployment. Software must also provide ability to translate any binary and/or proprietary data formats to common accessible formats such comma delimited text and/or Matlab formats.

· Enclosures, sensors and cables should be made of corrosion resistant materials such as plastics and polyurethane, use of metals to be kept to a minimum and to corrosion resistant alloys such as stainless steel, copper and titanium. The instrument shall operate to at least 100 m depth.

· All necessary cables (if required) and any other hardware necessary to communicate with the instrument shall be provided with the exception of host PC computer.