Typically, each zip folder for a deployment period contains two data files from a velocimeter and one data file from a CTD, each of which include data from an optical backscatter sensor. Data were sequentially added to this data release as they are retrieved and post-processed. Users are advised to read the metadata for each part of this data release carefully for additional details.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
A formal accuracy assessment of the horizontal positional information in the data set has either not been conducted, or is not applicable.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
There are two sources of uncertainty associated with vertical positioning of the instruments: 1) the measuring tools used during instrument mounting; and, 2) the amount of settling that occurs during deployment. There was no evidence that the platforms settled to a large degree, they are easily lifted by one person, the sediment tends to be very compacted in the study area, and analysis of distance to bed data did not show gradients over the duration of deployment. The measuring tools used to mount the instruments onto the platforms have a resolution of 0.1 cm resulting in an uncertainty of 0.05 cm.
Source_Information:
Source_Citation:
Citation_Information:
Originator: The Iowa Environmental Mesonet (IEM)
Publication_Date: 2017
Title: ASOS-AWOS-METAR Data Download
Publication_Information:
Publication_Place: Ames, IA
Publisher: Iowa State University
Online_Linkage:
Type_of_Source_Media: Digital Resources
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20170531
Ending_Date: 20171003
Source_Currentness_Reference: observed
Source_Citation_Abbreviation: IEM
Source_Contribution:
Source information used in support of the development of the dataset. Local atmospheric readings were obtained from the IEM database to use during post-processing of the data to adjust for local atmospheric deviations.
Process_Step:
Process_Description:
Instruments included in deployment are: RBR CTD+, Seapoint turbidity meter, Nortek single point acoustic doppler velocimeter.
Process_Date: 20170531
Process_Step:
Process_Description:
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.
Process_Date: 20170728
Process_Step:
Process_Description:
Instruments were retrieved. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Process_Date: 20171003
Process_Step:
Process_Description:
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.
Process_Date: 20171003
Process_Step:
Process_Description:
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.
Process_Date: 20171003
Process_Step:
Process_Description:
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).
Process_Date: 20171003
Process_Step:
Process_Description:
Corrected the original publication date for Larger Work Citation to conform to new guidance issued regarding data release revisions.
Process_Date: 20191007
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Susan A Cochran
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Address:
Address_Type: mailing and physical
Address: 2885 Mission St.
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060
Country: United States
Contact_Voice_Telephone: 831-460-7545
Contact_Electronic_Mail_Address: scochran@usgs.gov
Process_Step:
Process_Description:
Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.
Process_Date: 20201019
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov