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Nortek Profiler Time Series

Data files for Nortek Current Profilers are described here. Ancillary data (e.g., temperature, pitch, roll) are also available independently.

Revision History

  • 2011XXXX: Initial NetCDF, CF1.5 compliant product released.
  • 20110302: Correction to algorithm for obtaining ENU (with respect to true North velocities). If instrument is mobile, a combination of instrument compass and local magnetic declination is used. If instrument is fixed position, the orientation determined at instrument deployment is used.
  • 20110110: Initial MAT product released
  • 20101130: Initial PRF product released

Formats

This data is available in PRF and MAT formats. Content descriptions and example files are provided below.

To produce these files, the following requirements apply:

  • A new file is started at the start of each day, when the maximum records per file is exceeded (currently set as 2880 for PRF and 43200 for MAT), or when the driver is restarted (this should account for configuration changes, site changes, etc).
  • Only records with valid checksums are included.
  • The instrument date/time field is replaced by the NEPTUNE timestamp at the beginning of the log file (since this timestamp is more accurate than the instrument clock), and the checksum is recalculated.
  • instrument hardware, head and user configuration strings are inserted as the first three lines of the PRF file and important parameters are parsed into MAT file. However, any data existing previous to accompanying configuration details being saved in the database cannot be interpreted (earlier than Fall 2009).
PRF

This binary format is specific to the manufacturer. When using Nortek data acquisition software, data is normally stored in this way. Although we use custom-built drivers to communicate with our instruments, we can use the raw data in the log file to produce the PRF file which can be interpreted by Nortek post-processing software (e.g., for the Nortek HR-Profilers click here.

This format is further described in the manufacturer's System Integrator Guide.

Example: BH_POD2_AD2M_20101018T160041.704.prf

MAT

MAT files (v7) can be opened using MathWorks MATLAB 7.0 or later. The file contains four structures: meta, data, config, and units.

meta: structure containing the following metadata fields.

  • deviceID: A unique identifier to represent the instrument within the NEPTUNE Canada observatory.
  • creationDate:Date and time (using ISO8601 format) that the data product was produced. This is a valuable indicator for comparing to other revisions of the same data product.
  • deviceHeading: Obtained at time of deployment (exception: devices on mobile platform will have NaN since they do not have a fixed heading).
  • siteName: Name corresponding to its latitude, longitude, depth position.
  • deviceName: A name given to the instrument.
  • deviceCode: A unique string for the instrument which is used to generate data product filenames.
  • locationName: The node of the NEPTUNE Canada observatory. Each location contains many sites.
  • samplingPeriod: Sampling rate of the instrument in seconds.
  • depth: Obtained at time of deployment.
  • lat: Obtained at time of deployment.
  • lon: Obtained at time of deployment.
  • dataProductVer: Version of data product.

data: structure containing the ADCP data, having the following fields.

  • time: vector, timestamp in datenum format (obtained from time the reading reached the shore station)
  • range: vector of distance to start of each bin
  • cellDepth: vector, starting depth of each cell calculated from range and deployment depth (may be inaccurate if instrument is vertically mobile)
  • u,v,w: 2D matrices, East/North/Up velocities relative to True North, derived using raw velocity matrix, orientation, coordinate system, transformation matrix and one of a) calculated magnetic declination based on time and location (for mobile adcps) or b) meta.deviceHeading (fixed position ADCPs)
  • velocity: 3D matrix, corresponds directly to output of instrument and so depends on configuration coordinate system
  • amplitude: 3D matrix, amplitude time-series for each of the three receivers
  • correlation: 3D matrix, signal correlation coefficient time-series for each of the three receivers (only available for HR-Profilers)
  • compassHeading: vector, magnetic compass heading time-series
  • pitch: vector, pitch time-series
  • roll: vector, roll time-series
  • pressure: vector, pressure time-series
  • temperature: vector, temperature time-series
  • soundSpeed: vector or constant (depending if configured to be fixed or computed)
  • voltage: vector, battery voltage time-series
  • error: vector, error code

config: structure containing Nortek Aquadopp Profiler configuration details. For details about the configuration parameters, refer to the manufacturer documentation.

  • SN: instrument type and serial number
  • headSN: head serial number
  • boardFrequency: board frequency
  • headFrequency: head frequency
  • fwVersion: firmware version
  • hwRevision: hardware revision
  • PICversion: PIC code version
  • avgInterval: time the instrument is actively measuring within the profile interval
  • measurementInterval: time between each measurement (i.e., data output rate)
  • compassUpdateRate: rate at which compass readings are updated
  • nbeams: number of transducers/beams.
  • ncells: number of cells
  • npings: number of pings per profile
  • beamAngle: angle of beams
  • blankingDistance: distance from the sensor head to the start of the first measurement cell. See Nortek forum discussion for calculation details.
  • cellSize: size of each cell. See Nortek forum discussion for calculation details.
  • coordSys: coordinates system of raw data (BEAM, XYZ or ENU)
  • orientation: Up or Down indicates the direction transducers are facing
  • transformationMatrix: matrix, used to convert from beam to xyz coordinates
  • correlationThreshold: correlation threshold for resolving ambiguities
  • velocityScaling: scaling for velocities from raw data, dependent on configuration

units: structure containing unit of measure for fields in structures above. For instance, units.pressure='decibar'.

Example: NortekADCP1504_20101022T000021Z.mat

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