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Long-term Oceanographic Observations in Western Massachusetts Bay, Offshore of Boston
U.S. Geological Survey Digital Data Series DDS-74, Version 2.0

Tidal Analysis

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Amplitude and phase of tidal constituents were computed using the tidal analysis program T_TIDE (Pawlowicz and others, 2002). The principal constituents are K1, O1, M2, N2, and S2. This report includes summary tables for the principal constituents as well as the full output from T_TIDE for each data record.

Summary of principal constituents:

Table headings for pressure:

  • Mooring number
  • Start time: beginning of data record analyzed
  • End time: end of data record analyzed
  • Amplitude: amplitude of tidal constituent (cm)
  • Amp. Error: estimate of error of tidal amplitude (cm)
  • Phase: phase of tidal constituent (degrees)
  • Phase error: estimate of error in tidal phase (degrees)
Table headings for current:
  • Mooring number
  • Start time: beginning of data record analyzed
  • End time: end of data record analyzed
  • Major axis: major axis of tidal ellipse (cm/s)
  • Maj. Error: error estimate for major axis of tidal ellipse (cm/s)
  • Minor axis: minor axis of tidal ellipse (cm/s)
  • Min error: error estimate for minor axis of tidal ellipse (cm/s)
  • Inclination: inclination of major axis (measured counter clockwise from east (degrees)
  • Inc. error: error estimate for inclination (degrees)
  • Phase: phase at time of major axis (degrees)
  • Phase error: error estimate for phase (degrees)

Site A

Pressure 1 mab O1 K1 M2 N2 S2
Current (PCM*) 5 mbs O1 K1 M2 N2 S2
Current (PCM*) 10 mab O1 K1 M2 N2 S2
Current (PCM*) 1 mab O1 K1 M2 N2 S2
Current (ADCP) 5 mbs O1 K1 M2 N2 S2
Current (ADCP) 15 mbs O1 K1 M2 N2 S2
Current (ADCP) Deepest Bin O1 K1 M2 N2 S2

Site B

Pressure 1 mab O1 K1 M2 N2 S2
Current (ADCP) 5 mbs O1 K1 M2 N2 S2
Current (ADCP) 10 mbs O1 K1 M2 N2 S2
Current (ADCP) Deepest Bin O1 K1 M2 N2 S2

Complete Tidal Analysis from T_TIDE:

Table headings for T_TIDE output:

  • tide: tidal constituent
  • freq: frequency (cycles/hour)
  • major: major axis of tidal ellipse (for current observations) (cm/s)
  • emaj: error estimate for major axis (cm/s)
  • minor: minor axis of tidal ellipse (cm/s)
  • emin: error estimate for minor axis (cm/s)
  • inc: inclination of major axis (counter clockwise from east) (degrees)
  • einc: error estimate for inclination (degrees)
  • phase: phase of at time of major axis (degrees)
  • ephase: error estimate of phase (degrees)
  • snr: signal to noise ratio

Site A

Pressure     1 mab
Current (PCM*) 5 mbs 10 mab 1 mab
Current (ADCP) 5 mbs 15 mbs Deepest Bin

Site B

Pressure     1 mab
Current (ADCP) 5 mbs 10 mbs Deepest Bin

* = Point Current Meter

Table containing a list of the depth of the deepest ADCP bin for each deployment.

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