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These data are published in Hirsh et al., see related publications section.
The moorings were deployed from June to October 2018. The moorings consisted of a subsurface mooring buoy anchored to a weight so that it was approximately 1 m below the surface at spring low tide. A 5 m line connected the subsurface buoy to a small float at the surface.
Inside Kelp Forest Mooring Instruments:
Outside Kelp Forest Mooring Instruments:
Calibration by taking discrete samples alongside sensors in situ can lead to relatively large uncertainties, especially in highly dynamic coastal environments (Bresnahan et al. 2014); therefore, we decided to calibrate sensors in a flow through tank where the pH is more stable, and multiple discrete samples for DIC and TA analysis could be collected. Prior to deployment, the mFET sensors logged in a tank for 6 days (3 discrete samples) and the SeapHOxes logged in an adjacent tank for 1 day (2 discrete samples). We estimate the accuracy of the pH sensor data to be ± 0.015.
Oxygen sensors were calibrated by making measurements in a black bucket filled with freshwater while bubbling air for 8 hours. We assumed 100% saturation and applied a gain correction to the raw sensor output (Bittig & Körtzinger, 2015; Bushinsky & Emerson, 2013; Johnson et al., 2015). Because the air-stone was placed at the bottom of the bucket, elsewhere we would expect slight over-saturation. However, since the depth of the bucket was < 40 cm, we estimate the accuracy of this calibration to be better than 1-2%. Post-deployment calibration indicated no drift in the oxygen sensors.
Sensor data were quality controlled with several steps. First, obviously erroneous data such as spikes were removed. When bubbles were present on the sensors they led to clearly erroneous data; for instance, pH values typically changed in a large, stepwise manner (usually >0.3 or more) with no correlation to temperature or O2.
Second, the sensors were deployed facing downwards on the mooring line, and bubbles from divers were sometimes trapped on the sensing surface for several hours, leading to incorrect sensor readings. The data bias by bubbles was clearly evident. Sensor data that showed short, stepwise shifts when divers were near the mooring were manually removed.
Finally, the first day of sensor data is not included in this data set to ensure that the instruments were fully equilibrated with environmental conditions.
BCO-DMO Processing notes:
An SBE 37-SM MicroCAT CTD recorder was deployed at mid depth on the mooring beginning in mid-August with sampling frequencies of 5 minutes.
The Sea-Bird MicroCAT CTD unit is a high-accuracy conductivity and temperature recorder based on the Sea-Bird SBE 37 MicroCAT series of products. It can be configured with optional pressure sensor, internal batteries, memory, built-in Inductive Modem, integral Pump, and/or SBE-43 Integrated Dissolved Oxygen sensor. Constructed of titanium and other non-corroding materials for long life with minimal maintenance, the MicroCAT is designed for long duration on moorings.
In a typical mooring, a modem module housed in the buoy communicates with underwater instruments and is interfaced to a computer or data logger via serial port. The computer or data logger is programmed to poll each instrument on the mooring for its data, and send the data to a telemetry transmitter (satellite link, cell phone, RF modem, etc.). The MicroCAT saves data in memory for upload after recovery, providing a data backup if real-time telemetry is interrupted.
2 HOBO Pro v2 temperature loggers (Onset Data Loggers, 1 minute sampling frequency)
The HOBO Water Temp Pro v2 temperature logger, manufactured by Onset Computer Corporation, has 12-bit resolution and a precision sensor for ±0.2°C accuracy over a wide temperature range. It is designed for extended deployment in fresh or salt water.
Operation range: -40° to 70°C (-40° to 158°F) in air; maximum sustained temperature of 50°C (122°F) in water Accuracy: 0.2°C over 0° to 50°C (0.36°F over 32° to 122°F) Resolution: 0.02°C at 25°C (0.04°F at 77°F) Response time: (90%) 5 minutes in water; 12 minutes in air moving 2 m/sec (typical) Stability (drift): 0.1°C (0.18°F) per year Real-time clock: ± 1 minute per month 0° to 50°C (32° to 122°F)
Additional information (http://www.onsetcomp.com/) Onset Computer Corporation 470 MacArthur Blvd Bourne, MA 02532
1 HOBO U20L pressure sensor (Onset Data Loggers, 1 minute sampling frequency)
The HOBO U20L is designed for monitoring changing water levels in a variety of applications including tidal areas, streams, lakes, wetlands, and groundwater. It outputs pressure, water level, and temperature data. The instrument can record samples, sensor measurements at each logging interval, and events data, occurrences such as a bad battery or host connected. The samples are recorded as absolute pressure values, which are later converted to water level readings using software. Absolute pressure is atmospheric pressure plus water head. The deployment of an additional HOBO U20L at the surface can be used to compensate for barometric pressure changes. Each instrument is individually calibrated. They require a coupler and optic base station or HOBO waterproof shuttle to connect to a computer. The instrument is operated with a 3.6 V lithium battery.
This series contains 3 models, U20L-01, U20L-02, and U20L-04, with different operation ranges, calibrated ranges, and burst pressures. The pressure sensor is temperature compensated between 0 and 40 degrees Celsius (C), and calibrated between 69 and a maximum of 400 kPa (depending on the model). Its accuracy is within 0.3 % of the full scale for absolute pressure, and 0.1 % FS for water level readings. The temperature sensor operates between -20 and 50 degrees C, with an accuracy of 0.44 deg C, and a resolution of 0.1 deg C. The drift is 0.1 deg C per year.
3 MiniDO2T dissolved oxygen loggers (Precision Measurement Engineering (PME), 5 minute sampling frequency)
An electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed
1 miniPAR sensor (PME, 1 minute sampling frequency). PME miniPAR sensors were paired with PME miniWIPERs set to wipe the PAR sensors every six hours to prevent biofouling.
A PAR sensor measures photosynthetically available (or active) radiation. The sensor measures photon flux density (photons per second per square meter) within the visible wavelength range (typically 400 to 700 nanometers). PAR gives an indication of the total energy available to plants for photosynthesis. This instrument name is used when specific type, make and model are not known.
The outside kelp mooring included one mFET pH sensor and the kelp mooring included 2 seapHOx sensors and 5 mFET pH sensors.
The SeapHOx and SeaFET are autonomous sensors originally designed and developed by the Todd Martz Lab at Scripps Institution of Oceanography. The SeaFET was designed to measure pH and temperature. The SeapHOx, designed later, combined the SeaFET with additional integrated sensors for dissolved oxygen and conductivity. Refer to Martz et al. 2010 (doi:10.4319/lom.2010.8.172).
The SeapHOx package is now produced by Sea-Bird Scientific and allows for integrated data collection of pH, temperature, salinity, and oxygen. Refer to Sea-Bird for specific model information.
3 SBE 56 thermistors (Sea-Bird Electronics, 1 minute sampling frequency)
A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.
Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range, typically 90C to 130C.
ID to distinguish depth
Mooring name: KELP = inside kelp forest mooring; OUTSIDE = mooring outside kelp forest
Latitude of mooring location, south is negative
Longitude of mooring location, west is negative
Meters above bottom
pH of water
Dissolved oxygen
oxygen saturation
Water temperature
Salinity
Pressure. Pressure at bottom (0 mab, depth_i=9) provides mab for surface (depth_id=1)
Photosynthetic Active Radiation
Timestap (date and time) in ISO format, UTC (yyyy-mm-ddThh:mmZ)
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