Data Processing Notes
Acoustic Surface Reverberation Experiment, 1991
15 Nov 2000, AJP
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General
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    Three surface moorings were deployed during ASREX-91. Two contained
    wave rider buoys (a Seatex Wavescan and an Endeco Wavetrack) and 
    were dedicated to surface wave measurement. The third contained a
    3 m discus buoy and was used as the platform for meteorological 
    and upper ocean observations. The discus buoy was also outfitted
    with an accelerometer package to measure pitch, roll and heave.

    Only the meteorological and oceanographic data from the discus
    mooring are documented here. The discus mooring was outfitted with
    two independent meteorological sensor systems, a VAWR and an IMET
    system. The two records agreed well, typically within the expected 
    sensor accuracy. The VAWR was used as the primary meteorological 
    system due to its longer record length.


Meteorology
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  General:

    The VAWR provided complete records of wind speed, wind direction,
    air temperature, sea surface temperature, barometric pressure, 
    relative humidity, longwave radiation, and shortwave radiation. 
    The VAWR data file obtained from magnetic tape had 392 record gaps
    that were interpolated to obtain a uniform time base. 

  Wind Direction:

    A magnetic variation (also referred to as magnetic declination) of
    +21.4 degrees was applied as a rotation to the east and north wind
    components. Speed and direction were computed from the components. 

    Wind directions are in oceanographic convention (direction
    towards), opposite to the meteorological convention (direction
    from).

  Sea surface temperature:

    A bias of -0.015 was applied to SST. 

  Precipitation:

    Precipitation was measured by the IMET system, but the record was
    not complete (1 Nov to 5 Dec 1991). These precipitation data are 
    not yet available.


Temperature 
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  Sampling:

    The sampling interval for the VMCMs was 1.875 min, whereas the
    Tpods sampled at 7.5 min and the VAWR (which provided the 1 m
    temperature) at 15 min.  VMCM temperature data were averaged 
    and the VAWR temperature was interpolated to match the Tpod 
    time base.

  Performance:

    All of the sensors returned complete temperature records.

  Calibration and Adjustments:

    In most cases temperature sensors were pre- and post- calibrated to
    within 0.02 C accuracy. A bias of -0.015 was applied to the VAWR
    temperature. 


Velocity
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  Sampling:

    All VMCMs sampled at 1.875 min.

  Performance:

    All of the sensors returned complete velocity records.

  Magnetic Variation: 

    A magnetic variation (also referred to as magnetic declination) of
    +21.4 degrees was applied as a rotation to the east and north
    velocity components. Speed and direction were computed from the
    components.