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QC Challenges of Collecting Time-Continuous Water
Quality Data: PacIOOS Water Quality Buoy (WQB) Data QC
by Michael Tomlinson & Eric De Carlo
Handout &Outline Handout contains most data products in presentation
Overview of Pacific Islands Ocean Observing System
PacIOOS water quality components
Presentation focuses on the NOAA/PMEL MapCO2 /
PacIOOS specifically Water Quality Buoy data QC
Manual data processing & QC (different time scales)
Annual (and beyond) QC & data adjustment with
Aquarius® software
Independent data (& estimate) validation
Final data release
What have we learned from 5 years of monitoring?
IOOS – National Ocean Observing
PacIOOS
PacIOOS
What does PacIOOS do?
Data Collection & QC
Data Aggregation
Data Visualization
Real-time Warnings
Provides Research Data
Outreach/Communication
Examples of Applications
Understanding Ocean Acidification Assessing the effects of storms on coastal
water quality (e.g., Tomlinson et al., 2011)
Water quality monitoring & sounding “all clear” after tsunamis (e.g., Fiedler et al., 2014)
Impacts of groundwater / surface water on
coastal marine ecosystems
NOAA/PMEL MapCO2/ PacIOOS WQBs (T, S, O2, CO2, pH, nitrate, turbidity, chlorophyll)
Nearshore Sensors (T, S, turbidity, chlorophyll)
Kilo Nalu Observatory (tides, waves, currents, acoustic backscatter, T)
Autonomous Underwater Vehicle (bathy, currents, T, S, chlorophyll, optical backscatter)
Synoptic manual event-driven sampling
NOAA/NWS Met Stations & Rain Gages
USGS Streamflow Gages
NOAA/NOS Tide Gages & Met Stations
HIDoH Beach Monitoring
NOAA/NDBC Open Ocean Data Buoys
Satellite Imagery
PacIOOS Water Quality Components
Water Quality Component Locations
NOAA/PMEL MapCO2/PacIOOS WQB Sensors Sensor Variable
SBE16plus V2 SEACAT®
Temperature Salinity Pressure
SBE63 DO® Diss. Oxygen
WET Labs FLNTUS®
Chlorophyll Turbidity
ISUS-V3® Nitrate
SeaFET® pH
LI-COR CO2® CO2
Data Processing & QC Flowchart
Figure 1
Twice-Daily Checks
Twice-Daily Checks (continued) Gaps in the WQB record on the website that did not exist (see graph below); caused by a problem with the Data Turbine
Manual Processing (every 3 days)
Monthly QC Check
MathCAD® Check of Spreadsheet
Coefficient Check
Check Spreadsheet Calculation
Monthly Time-Series Plot
WQB Data QC 1 Year & Beyond
Aquarius "whiteboard" used to QC and adjust, as necessary, data from the PacIOOS WQBs. In addition to the WQB data, other data are used as surrogates to help QC the data and guide any necessary adjustments. The raw, adjusted, surrogate, and discrete (C&CH) data are plotted as time-series.
Figure 2
Partial Aquarius® Whiteboard (close-up)
Rare Adjustment to Salinity Data
Raw Data
Adjusted Data
Note: Adjusted data are always flagged as ESTIMATES
Figure 3
Not So Rare Adjustment of SBE43® Dissolved Oxygen (DO) Sensor
Figure 4
WET Labs FLNTUS® Chlorophyll & Turbidity Sensor – Ultimate Challenge
Figure 5
Great when the sensor is working …
Figure 6
… a real challenge when it isn’t working
Figure 7
Final Adjusted Turbidity & Surrogates
Figure 8
Chlorophyll had its own challenges …
Figure 9
… but adjustable trim correction …
Figure 10
… salvaged some of the data!
Figure 11
Problems Evident After 1+ Years (SBE43® Membrane DO Sensor)
Sensor began to drift immediately after deployment and continued throughout the entire deployment period, regardless of the time of year. SBE conceded there was a problem but cannot explain it.
Figure 12
Correcting the SBE43® DO Problem
Figure 13
Independent Data QC Check
C&CH NPDES Receiving Water
Monitoring Station
Figure 14
Raw & Adj. WQB Data and C&CH NPDES Data
Figure 15
Figure 16
Master PacIOOS WQB Spreadsheets
PacIOOS Water Quality Webpage
What have we learned in 5 years?
QC must be conducted at different time scales
Need one extra suite of sensors for annual servicing
Some sensors (e.g., SBE43® DO membrane sensor)
do not work well in shallow, subtropical water
Although expensive, need another suite of sensors with
comparable precision & accuracy for servicing checks
Data QC is not part-time job nor can it be automated …
… unless we emulate the National Data Buoy Center &
have redundant sensors (very expensive)
Routine monitoring provides valuable research data,
e.g., tsunami water quality effects (Fiedler et al., 2014)
Questions & Contact Information
www.pacioos.org
Michael Tomlinson UHM Oceanography Flagstaff, AZ [email protected] 928-266-2236 (cell)