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 mtomlins@hawaii.edu 928-266-2236 (cell)