MetaData - Fish Creek Watershed Observatory – Lake Monitoring
Description:
Water quality time series files for six or more lakes on the North Slope of Alaska in the Fish Creek Watershed near Nuiqsut. These include time series of water temperature (bed and surface), lake depth, lake elevation, and in some cases dissolved oxygen, specific conductivity, and temperature measured in other place in the water column or above the lake surface.  

Details:
These folders contain .csv files of parameter time series collected year round. Data collected at the same locations using the same configuration will be found in the yearly files, where the year is defined as that year when the data were downloaded.
Generally, bed pressure transduces (U20) are attached to an anchor that is attached to a line and two buoys. Surface sensors are suspended below the first surface buoy and mid-water column sensor attached below a buoy ~0.5 m above the anchor An Onset computer U12-015 water temperature data logger is affixed to the rope 30 cm below the float. Another data logger (U20) is attached to the rope just above the anchor. The U20 is a water level/water temperature logger, so records the change in the water depth over the period of record. The water level is calibrated and corrected using the barometric pressure record from the nearest terrestrial met station. This is done in the Onset Hoboware software. All sensor specifications are shown below. All instruments are retrieved and downloaded in July or August, with corresponding check samples made at this time and water surface elevations measured with a differential GPS and/or georeferenced staff gage (tape down measurement). It should be noted that there is often some movement of the floats that get entrained by the moving ice slab in spring, which typically happens over subhourly time intervals (i.e. near instantaneously). Water depth and elevation data during this time are flagged as NaN, as are all ice covered or otherwise ice affected periods. All loggers record hourly measurements on the hour using Alaska Standard Time (AKST). Specific column heading a provided for each file along with units. Once downloaded, data is quality controlled first using Onset Software to correct measurements for barometric pressure and temperature and according to field measurements typically recorded in April and August. Next, data is corrected to lab measured calibration equations (linear corrections based on temperature and water level variations) and data is plotted versus time and other parameters to identify outliers, which are flagged as NaN. Other discrepancies that cannot be corrected based on field observations are also flagged as NaN. Hourly datasets are summarized as daily mean values for full 24-hr monitoring periods. 

Pressure and Water Level Measurements U20-001-01 and U20-001-01-Ti
Operation Range 0 to 207 kPa (0 to 30 psia); approximately 0 to 9 m (0 to 30 ft) of water depth at sea level, or 0 to 12 m (0 to 40 ft) of water at 3,000 m (10,000 ft) of altitude
Factory Calibrated Range 69 to 207 kPa (10 to 30 psia), 0° to 40°C (32° to 104°F)
Burst Pressure 310 kPa (45 psia) or 18 m (60 ft) depth
Water Level Accuracy* Typical error: ±0.05% FS, 0.5 cm (0.015 ft) water 
Maximum error: ±0.1% FS, 1.0 cm (0.03 ft) water
Raw Pressure Accuracy** ±0.3% FS, 0.62 kPa (0.09 psi) maximum error
Resolution < 0.02 kPa (0.003 psi), 0.21 cm (0.007 ft) water
Pressure Response Time (90%) < 1 second
Thermal Response Time (90%)*** Approximately 10 minutes in water to achieve full temperature compensation of the pressure sensor

Temperature Measurements (All Models)
Operation Range -20° to 50°C (-4° to 122°F) 
Accuracy ±0.44°C from 0° to 50°C (±0.79°F from 32° to 122°F), see Plot A 
Resolution 0.10°C at 25°C (0.18°F at 77°F), see Plot A 
Response Time (90%) 3.5 minutes in water (typical) 
Stability (Drift) 0.1°C (0.18°F) per year 


HOBO U12 Stainless Temperature Data Logger - U12-015
Measurement range: -40° to 125°C (-40° to 257°F)
Accuracy: ± 0.25°C from 0° to 50°C (± 0.45°F from 32° to 122°F), see Plot A
Resolution: 0.03°C at 25°C (0.05°F at 77°F), see Plot A
Drift: 0.05°C/year + 0.1°C/1000 hrs above 100°C (0.09°F/year + 0.2°F/1000 hrs above 212°F)
Response time in 1 m/s (2.2 mph) airflow:
U12-015: < 10 minutes, typical to 90% 
U12-015-02: 2.25 minutes, typical to 90%
Response time in water:
U12-015: < 3.5 minutes, typical to 90% 
U12-015-02: 20 seconds, typical to 90%
Time accuracy: ± 2 minute per month at 25°C (77°F), see Plot B
Operating environment: Air, water, steam, 0 to 100% RH
Operating temperature:
Logging: -40° to 125°C (-40° to 257°F)
Launch/readout: 0° to 50°C (32° to 122°F), per USB specification

HOBO Conductivity Data Logger - U24-001
Memory - 18,500 temperature and conductivity measurements when using one conductivity range; 14,400 sets of measurements when using both conductivity ranges (64kbytes)
Sample rate - 1 second to 18 hrs, fixed or multiple-rate sampling with up to 8 user-defined sampling intervals
Battery life - 3 years (@ 1 min logging)
Maximum Depth - 70 m (225')
Operating Range - -2 to 36°C (28° to 97°F) - non freezing
Weight - 193 gm (6.82 ounces), buoyancy in freshwater: -59.8 gm (-2.11 ounces)
Size - 3.18 cm diameter x 16.5 cm, with 6.3 mm mounting hole (1.25" diameter x 6.5", ¼" hole)
Calibrated Range - Conductivity: Low Range: 0 to 1,000 µS/cm; Full Range: 0 to 10,000 µS/cm - Temperature: 5 to 35C (41 to 95F)
Accuracy - Conductivity: 3% of reading, or 5 µS/cm, whichever is greater / Temperature: 0.1C (0.2F)
Resolution -Conductivity: 1 uS/cm - Temperature: 0.01°C (0.02°F)
Response time - 1 second to 90% of change
HOBO Dissolved Oxygen Logger - U26-001

Dissolved Oxygen 
Sensor Type Optical
Measurement Range 0 to 30 mg/L
Calibrated Range 0 to 20 mg/L; 0 to 35°C (32 to 95°F) 
Accuracy 0.2 mg/L up to 8 mg/L; 0.5 mg/L from 8 to 20 mg/L 
Resolution 0.02 mg/L 
Response Time To 90% in less than 2 minutes
DO Sensor Cap Life 6 months, cap expires 7 months after initialization
Temperature 
Temperature Measurement/Operating Range -5 to 40°C (23 to 104°F); non-Freezing
Temperature Accuracy 0.2°C (0.36°F) 
Temperature Resolution 0.02°C (0.04°F) 
Response Time To 90% in less than 30 minutes 
Logger 
Memory 21,700 sets of DO and temperature measurements (64 KB total memory)
Logging Rate 1 minute to 18 hours
Time Accuracy ±1 minute per month at 0 to 50°C (32 to 122°F)
Battery 3.6 V lithium battery; factory replaceable
Battery Life 3 years (at 5 minute logging)
Download Type Optical
Depth Rating 100 m (328 ft)
Wetted Materials Black Delrin®, PVC, EPDM o-rings, silicone bronze screws; rated for saltwater use 
Size 39.6 mm diameter x 266.7 mm length (1.56 x 10.5 inches)
Weight 464 g (16.37 oz)


Author(s):
Christopher D. Arp


Metadata Contact(s):
Christopher D. Arp, cdarp@alaska.edu

GCMD Science Keyword:
Terrestrial Hydrosphere > Surface Water > Water Depth
Terrestrial Hydrosphere > Surface Water > Lakes
Terrestrial Hydrosphere > Water Quality/Water Chemistry > Water Temperature

ISO Topic:
climatologyMeteorologyAtmosphere
inlandWaters

Data Format(s):
Other ASCII 

Time Frequency
(ies):
Hourly to Daily 

Location(s):
Geographic Region > Arctic
Geographic Region > Polar
United States Of America > Alaska

Resolution(s):
Point


Progress:
In progress 

Date Created:
2013-01-22 15:10:45

Date Last Updated:
2013-02-06 14:16:18

Language:
English

Platform(s):
Mooring 
Automated Surface Observing System 

Instrument
(s):
Temperature Loggers 
Thermistors 
Water Level Gauges
Conductivity Sensors
Dissolved Oxygen Sensors