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Columbia River estuary, Grays Bay
US Coast Guard Day Mark ‘13’
Type: Endurance physical station
Active: September 1998 – Present
Instrument Depth: 1.6m (below NGVD29)
Monitoring Purpose: Provides continuous monitoring of baseline parameters.
Network Significance: Located near the seaward entrance of Grays Bay, a lateral embayment on the north side of the estuary that may provide critical habitat for juvenile salmon and steelhead. Seawater intrusion here is highly sensitive to tidal mixing conditions and seasonal river discharge.
Design: A fixed station moored to one leg of USCG aid to navigation. Sensor is deployed at 1.6m.
Instrumentation set is subject to change based on research needs
Third-party requests for sensor deployment welcome, pending logistics and funding availability.
Power: via solar panel/12v battery
Installed and operated by: Oregon Health & Science University
Data Availability: Grays Point observations are available through the Internet both (1) in near real-time as raw data and (2) with a lag time of about one month as quality controlled data. All data from the SATURN observation network is available through both (1) the CMOP Data Center and (2) NANOOS, the Pacific Northwest regional federation of NOAA's Integrated Ocean Observing System (IOOS).
Data is openly available, pursuant of the disclaimer below:
Disclaimer: All data are collected as a part of a scientific project, and are provided “as is,” without explicit or implicit warranty of accuracy or suitability for any purpose. User is fully responsible for using the data, and should ensure suitable quality assessment prior to use. Data should not be used in any situation involving the possibility of loss of life or injury, loss of property or financial loss.
QA/QC Protocols: QA/QC for Time, Temperature, and Salinity. Protocols for other variables are in development.
|Field operations||Data flow management||Specialty sensor management|
Michael Wilkin (Team Leader)
Dr. David Hansen (Team Leader)
|Scientific Direction: Dr. Antonio Baptista|
Grays Point is maintained as core CMOP infrastructure via a National Science Foundation (NSF) cooperative agreement. The Murdoch Charitable Trust provided major instrumentation support and the station is operated by OHSU. All SATURN stations contribute data to the Northwest Association of Networked Ocean Observing Systems (NANOOS).
Credits: We recommend the following citation for all publications using CMOP data: "This study utilized data collected at the SATURN observation network, operated by the Center for Coastal Margin Observation & Prediction (CMOP), under the direction of Dr. Antonio Baptista and with support from the National Science Foundation (OCE-0424602), the National Oceanic and Atmospheric Administration (NOAA Fisheries and NANOOS), U. S. Army Corps of Engineers, Bonneville Power Administration, Office of Naval Research, and the M. J. Murdock Charitable Trust."
The SATURN endurance biogeochemical stations are designed to provide river-to-shelf gradients of the following set of baseline water parameters: conductivity, temperature, salinity via conductivity and temperature, fluorescence, turbidity, colored dissolved organic matter (CDOM), dissolved oxygen (DO) and nitrate.
However, because SATURN is still evolving, sensors for some of the baseline parameters may not yet be installed at all endurance biogeochemical stations. Status per station:
Installed sensors are occasionally offline, for maintenance or otherwise. Check real-time status at each station’s web page.
Data Quality Assurance Methods: CTs
Salinity and temperature data collected at the SATURN stations has been quality checked and corrected using the following methods. There are 2 sources of data, download and telemetry, and they have slightly different processing methods. Download data is collected from the instruments when they are removed from an installation. Telemetry data is received in real time across the radio network. Where available, download data is provided in preference over telemetry data.
Data downloaded from an instrument relies on the accuracy of the computer used to initialize the instrument (this is checked using standard NTP processes) and drift of the instrument's internal clock. Data received through the telemetry network will show an error if the receiving computer loses contact with an NTP server for a significant amount of time, or if the radio link itself becomes broken or intermittent.
Data from download and telemetry are compared to assess the quality of the time stamp, any errors that cannot be resolved beyond 5 minutes result in the entire data point being removed from the record.
The quality of the temperature data is confirmed by post-deployment instrument calibration checks.
The quality of the data during a deployment is also confirmed by cross comparisons of the temperature of fresh water across multiple stations. Agreement within 0.2 C for fresh water temperature is seen across multiple instruments. The significance of the failure of a particular instrument to meet this criteria is judged on a station by station basis.
Temperature data has also been checked for extreme outliers. Extreme outliers are removed from the final data.
The major source of error for salinity data is biofouling of the conductivity sensor. Biofouling produces an increasingly depressed salinity reading, and can produce errors greater than 50% of the actual salinity. Development of automated detectors of biofouling in the data record is ongoing. Currently, the detection of biofouling is performed manually by comparing the slope of the temperature-salinity diagram for a particular instrument to the expected slope of the estuary wide temperature-salinity diagram.
Salinity is also checked for extreme outliers. Extreme outliers and data determined to be subject to biofouling are removed from the final data.
Station: Grays Point (USCG day mark green 13)
|Variable||N Recorded||N After QA||N Possible
|% Possible||% After QA|
The preceding table was generated by computing the number of possible samples per year across all instrument deployments at a given station and depth.
- MSL depth is the NGVD29 depth of the instrument deployments in meters. Several stations have had multiple simultaneous deployments at varying depths, e.g. red26 and am169.
- The three physical variables observed are salinity, temperature, and pressure expressed as depth. Not all instruments have pressure sensors and a small number (e.g. Woody Island) do not have conductivity sensors for determining salinity.
- The 'N Recorded' column gives the number of data records retrieved from the deployment(s) and includes data received from telemetry and data downloaded from the instruments internal recorder. Not all instruments have internal recorders so records received are from telemetry only.
- The 'N After QA' column is the number of records for each physical variable that survived quality control procedures. Salinity is most sensitive to biofouling and is the variable most likely to fail quality control tests.
- The 'N Possible Records' is the number of records that could be seen given the length of cumulative deployments and the sample rate for each deployment.
- The '% Possible' column is the percentage of actual records retrieved. The 'N/A' indicates possible problems in the database such as an incorrect sampling rate or computational issues with this application that need further investigation.
- The '% After QA' column is the percentage of records surviving quality control procedures. The 'N/A' indicates possible problems in the database such as an incorrect sampling rate or computational issues with this application that need further investigation.