Water-level, wind-wave, and suspended-sediment concentration (SSC) time-series data from Little Holland Tract (station HWA), Sacramento-San Joaquin Delta, California, 2015

Instruments included in deployment are: RBR duo bursting pressure sensor, and RBR virtuoso turbidity meter.

Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.

Data were accumulated into NetCDF files. During post-processing, data collected when instruments were out of the water, and data degraded by biological fouling, were removed from the time series. Bad data points were identified by 1) the deployment and recovery times; 2) pressure readings equal to or less than 3 cm of water; and, 3) amplitude or correlation values outside of predetermined quality thresholds for the velocimeter. Pressure data were adjusted from absolute pressure to hydrostatic pressure by removing local atmospheric pressure. Local atmospheric pressure was obtained from IEM for the Travis Air Force Base (SUU) station, which is located 15 miles from the study site.

Optical backscatter (OBS) data were put through a rigorous cleaning process, as these types of data are inherently noisy. First, the data were inspected for extended periods of time (typically many days) of unrealistic values that did not follow typical trends. These periods of bad data, believed to be caused by vegetation blocking the sensor, were manually removed from the time series. Second, large values of the first derivative of the time series were removed, which indicate unrealistic single point spikes in the data. Spikes were identified by change thresholds of +/-70 mg/L for the burst-average time series and +/-1 mg/L within the bursts. Third, readings above 90 percent of the maximum instrument voltage were removed. In particularly noisy data, points deviating more than 3 standard deviations from the running mean were removed. Finally, 'island' points were identified (and removed) by checking for real-value points with both neighbors flagged as bad. Bad data points were then replaced by linear interpolation, except for the large chunks that were removed in the first step of filtering. The OBS data were converted to suspended-sediment concentration using calibration constants derived from linear regression between OBS data and sediment concentration measured in water samples collected in the study area.

Files were named with a convention that uses a 13-digit alpha-numeric code. The first two characters for this dataset are all 'DL' for the experiment name. For deployments 1 - 9, the third character is a number indicating which deployment period the data comes from (1, 2, 3, etc.); the fourth and fifth positions represent the calendar year in which the first data point in the file was taken (15, 2015; 16, 2016). Deployments 10 to 13 occurred during the year 2017. In these cases, the third and fourth character indicates the deployment number while a '7' in the fifth position represents calendar year. The sixth position is a letter indicating the water body/region (L, Liberty Island; H, Little Holland Tract). The seventh position is a letter representing the station type (V, velocity station; W, wind-wave station). The eighth position represents the location of the station (A, B, C, etc.) within the water body/region. Next is a three-character code for the instrument type (vec, Nortek's Acoustic Doppler Velocimeter; rbr, RBR's bursting pressure sensor; ctd, RBR's CTD; vir, RBR's Virtuosos turbidity sensor). There are an additional two characters for the instruments that collect in a bursting pattern to indicate if the burst is included in the file or the statistics of the burst, this indicator is omitted if there is no bursting pattern (-b, burst; -s, statistics).

Corrected the original publication date for Citation and for Larger Work Citation to conform to new guidance issued regarding data release revisions. For information regarding the original version of this data release, see Point of Contact section of this metadata file.

Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.

Performed minor edits to the metadata to correct typos. No data were changed