PIE LTER, Year 2020, 15 minute interval, water quality measurements of water column temperature, salinity, oxygen, and depth near the mouth of Plum Island Sound, Massachusetts


Year 2020, 15 minute measurements of water column temperature, salinity, oxygen and depth in Plum Island Sound at the Ipswich Bay Yacht Club, Ipswich, MA. There were sifgnificant datalogger power,  radio telecommunication and sonde cabling corrosion issues during the Covid-19 Spring - Fall of 2020. There are many missing data time periods due to issues and some limited field work capabilities due to Covid working restrictions.

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Measurements are made using a YSI 6600 water quality  datalogging sonde. YSI Sonde sensors consist of 6150  optical dissolved oxygen probe , 6560 conductivity/temperature probe (thermistor) and non-vented level depth sensor (stainless steel strain gauge).

Missing data or blank values (NA) are caused by maintenance time periods or where sensor measurements are obviously wrong in the context of what would be expected. For example, the conductivity sensor has a relatively small opening and chamber for the conductivity electrodes, the estuary can have varying suspended sediment/detrital loads moving in the water column which enter the conductivity cell shorting out the electrodes making a faulty conductivity measurement (lower than expected). Oxygen measurements are dependent upon the conductivity measurements so the oxygen also becomes erroneous. Obvious measurements/data errors have been removed from the data set however the user of this data should also conduct their own data analysis to determine if the data are suitable for their particular situation.


Typical sensor/data problems are:

For oxygen: Poor/inaccurate conductivity measurements will affect the dissolved oxygen accuracy
For conductivity: Conductivity cell can have detrital material stuck in it, shorting out cell, resulting in lower than expected conductivity.
For depth: Depth strain gage pressure sensor may come out of the water at low tides resulting in many "zero" depth readings or sometimes negative values. Depths are not corrected for atmospheric pressure changes.

YSI Dissolved oxygen % saturation reporting can vary depending upon how the  oxygen is calibrated.
For this data set two Oxygen percent saturation values are reported.

ODO%YSI variable name represents  a YSI calibration in air, from Standard Methods, refers to calibration at a particular ATM pressure which allows DO% for calibration to fluctuate above/below 100% when ATM is above/below reference 760 or 1 ATM

ODO%Local variable name represents an oxygen calibration  in air at a particular ATM pressure but it forces the DO% to be 100%, does not allow it to be under or above if ATM is above/below 760.

ODO%Local data should be used for metabolism studies when correcting for diffusion based on gradient deviations from 100% which by definition is the % saturation of oxygen in air.

ODO%YSI should not be used since it would require a known ATM pressure at each interval to calculate the ATM % saturation of oxygen to be use for that interval, probably a small correction anyway.

Concentration of DO remains the same for either calibration.


A Campbell CR1000 logs the data which is also written to a CF card.

Incomplete data issues
Data is not continuous, many gaps where datalogger power failed or sonde had corrosion or leaks.
June 17, 2020 to August 12, 2020, sonde cable leakage and sonde pin corrosion issues.
Sonde logging issues 21Sep2020 to 05Nov2020 , sonde didn't log after set up  9/29/2020 then did  log  starting 10/19/2020 but stopped 10/27/2020.


Measurements complete for 2020.

Version 01: 07 September 2021, New data and metadata. Used MarcrosExportEML_HTML (working)pie_excel2007_Jul2021.xlsm 7/26/2021 9:04 AM for QA/QC to EML 2.1.0.


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