Seasonal particle responses to near-bed shear stress in a shallow, wave- and current-driven environment

Novel analysis of in-situ acoustic and optical data collected in a shallow, wave- and current-driven environment enabled determination of: (1) particle characteristics that were most affected by near-bed physical forcing over seasonal scales, and (2) characteristic shear stress, tchar, at which the rate of change to particle characteristics was most pronounced. Near-bed forcing and particle responses varied by season. Results indicated that moderate tchar values of 0.125 Pa drove changes in particle composition during summer. In winter, particle concentration effects were most affected at tchar of 0.05 Pa, suggesting dominance of fluff layer resuspension. Changes to particle size were most relevant during a biologically productive springtime period, with initiation of particle disaggregation occurring most commonly at tchar of 0.25 Pa. These results suggest that it may be more important to parameterize tchar, as opposed to critical shear stress for erosion, for sediment transport models..., This repository contains field data collected as part of the NSF OCE-1736668 project examining boundary layer and sediment dynamics in South San Francisco Bay that are associated with the paper, “Seasonal Particle Responses to Near-Bed Shear Stress in a Shallow, Wave- and Current-Driven Environment”. The project consisted of three field deployments: Summer (July - August 2018), Winter (January - February 2019), and Spring (April - May 2019). The data set currently includes data products computed from measurements taken by acoustic Doppler velocimeters (turbulent momentum and sediment fluxes), CTD (salinity, temperature, pressure), LISST (suspended sediment particle size distributions), backscattering meters, and an absorption-attenuation meter. We encourage the free use of this dataset, provided that it is properly cited.
The data set currently includes time series data products derived from measurements taken by Nortek Vector acoustic Doppler velocimeters (turbulent momentum and sedime..., QA/QC procedures followed IOOS standards for relevant variables, as well as community-accepted optical data analysis correction and calibration protocols. Vectrino data are QC/QC’ed in the following manner: any measurement with signal-to-noise ratio (SNR) < 10 or correlation < 20 counts is NaN'd out. Measurements below the bed are NaN'd out, where the bed position is determined through the Vectrino boundary finding algorithm. This is relatively minimal QC, so the beam correlations and SNR are included for further processing. The ADP data are not filtered in time or space, though measurements above the free surface are replaced by NaN. ADV outliers were removed and interpolated over. Outliers were defined as data points with any beam correlation < 30 counts, a velocity measurement outside of 5 standard deviations of the median, or above a certain magnitude (which varied for each data set). LISST data were processed using manufacturer provided scripts. Additional QA/QC processing...,