Field measurements of water column optical properties from the upper Sacramento River in northern California, September 13, 2017, and similar data from several other rivers

Field measurements of various optical properties of the water column were acquired from a reach of the upper Sacramento River in northern California, September 13, 2017, to support research on remote sensing of rivers, particularly estimation of water depth from passive optical image data. The field measurements included in this data release include several parameters measured with three different instruments. A WetLabs EcoTriplet multi-probe was used to measure the volume scattering coefficient (Beta) at 700 nm, the scattering coefficient (b) at 700 nm, chlorophyll concentration, colored dissolved organic matter (CDOM) concentration, and turbidity. A Sequoia Scientific LISST-100X was used to measure the total mass concentration of suspended sediment and the particle size distribution of that sediment. A WetLabs ac-s was used to measure spectra of the beam absorption (a) and beam attenuation (c) coefficients at 81 wavelengths from 399.6-746.5 nm. All measurements were made from a boat by lowering each sensor into the water in turn. Each instrument was allowed to measure a time series of data for 2-3 minutes and the values reported in this data release are time averages over the entire sample duration. Data were collected at three locations near the confluence of Cottonwood Creek with the Sacramento River and positions were recorded with a Trimble Geo7X GPS receiver; the original GPS data was differentially corrected using permanent GPS base stations with the Trimble Pathfinder Office software program. The coordinates of each measurement are included in the files comprising this data release and are in the UTM Zone 10N projection and NAD83 datum, with units of meters. Software provided by the manufacturer of each instrument was used to control the sensor in the field, record data to a computer, and export the raw data. Additional data processing (i.e., organization, plotting, and time averaging) was completed using custom functions developed in MATLAB. This data release consists of .csv files with the time-averaged values of each optical parameter at each of the three measurement locations; please see the metadata for further information on these files. This field-based data set played a valuable role in developing improved methods for mapping river bathymetry from remotely sensed data and understanding the limitations of spectrally based depth retrieval. In addition to these measurements from the Sacramento River, this data release includes a compilation of similar optical field data from several other rivers where studies have been conducted to develop methods for remote sensing of river bathymetry. These data were all collected using the methods and instruments described above for the Sacaramento River and provide a database for evaluating the effects of water column optical properties on spectrally based depth retrieval. This compilation is provided in .csv data files and a Google Earth .kmz file with locations.

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  "geospatial"
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