Data Processing and Quality Checks
A preliminary visual data quality check was performed on raw Hydra data
from both the beach pods and jetty tripods using Sontek ViewHydra software.
Data were extracted from raw data files (*.adr) using SonTek Hydra extraction
software and written to ASCII time series (*.ts), header (*.hdr) and control (*.ctl)
files. All remaining processing and post-processing was accomplished using in-
house PI Engineering software.
Processing and quality checking of extracted time series files consisted of the
following steps:
a. Plotting header file parameters (*.HDR): Heading, pitch, and roll angles,
mean temperature, and mean pressure, and bed position (if relevant) were
plotted as time series as a step in the data quality check process to
identify periods when instruments may have shifted position or been
subject to burial or fouling.
(preprocadvhts_v5.m) and associated subroutines processed the extracted
time series files and produced corrected and calibrated ASCII time series
files (*.tsc). The routine accomplished the following:
(1) Horizontal components (E, N) of ADVO velocities were corrected
from magnetic north to true north direction using the magnetic
declination for the location and time of deployment.
(2) Pressure measurements were converted to static water depth above
the ADV using mean barometric pressure and water density
(calculated from temperature and estimated salinity) during the
deployment period (p2h.m). Measured water temperature and
estimated salinity were converted to water density using the
International Equation of State of Seawater 1980 (IES80) (Folonoff
and Millard 1983). Bursts were eliminated from post-processing
analyses that were above the water surface through comparing the
height of the bin with the water depth mean.
(3) Static water depths were converted to water-surface elevation series
suitable for wave height and period calculation by correcting for
pressure attenuation as a function of depth and wave frequency
(p2eta.m). Corrections were carried out in the frequency domain and
converted to the time domain for output. The attenuation correction
factor is based on the linear wave theory dispersion relation and the
maximum frequency cutoff is based on that reported by Earle,
McGehee, and Tubman (1995) and is dependent on the water depth.
(4) Optical backscatterance sensor (OBS) counts were converted to
suspended sediment concentration using laboratory calibration
coefficients (obscal-os.txt). OBS on the SIDSEP were calibrated in a
turbidity tank with bed sediment from the deployment site prior to
the deployment. OBS on the HESTT were post-calibrated using
sediment from a grab sample collected near sta OS 6. Data were
inspected for evidence of bio-fouling and sensor burial. Bio-fouling
D17
Appendix D Field Data Collection
Previous Page
