Fort Point ShoreStation Sensor Information

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Instrument Type: Sea-Bird Electronics SBE 16+ SEACAT

Installed: 10/8/2004

Description: Self contained conductivity and temperature sensor, with strain gauge pressure sensor. Pumped during sampling with SBE 5T submersible pump.

fort point ctdLocation: Water sampled close to Fort Point pier, San Francisco.
Latitude 37° 48' 23.8674 N
Longitude 122° 27' 58.32 W

Specifications:

Temperature
Range: -5 to +35 °C
Resolution: 0.0001 °C
Accuracy: 0.005 °C

Conductivity
Range: 0 to 9 S/m
Resolution: 0.00005 S/m
Accuracy: 0.0005 S/m

Pressure
Range: 0 to 44 psu
Resolution: 0.002 % of full scale range
Accuracy: 0.1% of full scale range

Acquisition Settings:
Sample interval = 5 minutes, 10 measurements per sample
Pumped during sample, with 10 second warm up

Instrument Type: WETLabs C-Star Transmissometer

Installed: 10/8/2004

Description: The C-Star measures light transmittance at a single wavelength over a known path. The LED light source provides light that transmits within a narrow bandwidth. A portion of the transmitted light is monitored by a reference detector and used in a feedback circuit to account for variations in the LED source over time, as well as changes in the instrument’s internal temperature. The light transits the sample volume and enters the receiver optics, where it passes through additional focusing optics and finally strikes a silicon photodiode detector which converts the amount of received light to a corresponding 0–5 V analog output signal which represents the amount of light received. The ratio of light gathered by the receiver to the amount originating at the source is the beam transmittance.

In general, losses of light propagating through water can be attributed to two primary causes: scattering and absorption. Suspended particles, phytoplankton, bacteria and dissolved organic matter, as well as the intrinsic optical properties of the water itself, all contribute to the losses sensed by the instrument.

fort point transmissometerLocation: Water sampled at Fort Point pier, San Francisco.
Latitude 37° 48' 23.8674 N
Longitude 122° 27' 58.32 W

Specifications:
Wavelength: 660 nm
Pathlength: 25 cm
Sensitivity: 1.25 mV
Beam Divergence: 0.8° in water
Bandwidth: ~ 20 nm

Acquisition Settings:
Sample interval: 60 seconds
Measurements per Sample: 1

Instrument Type:  Seapoint Chlorophyll Fluorometer

Installed: 10/8/2004

Description: High performance instrument of in situ measurements of chlorophyll a.  The open sample volume has good ambient light rejection and a low temperature coefficient.

fort point fluorometerLocation: Water sampled at Fort Point pier, San Francisco.
Latitude 37° 48' 23.8674 N
Longitude 122° 27' 58.32 W

Installed: 10/8/2004

Specifications
Excitation Wavelength:  470 nm peak, 30 nm FBHM
Emission Wavelength:  685 nm peak, 30 nm FBHM
Sensing Volume:  340 mm3
Min. Detectable Level:  0.02 µg/l
Operating Temperature:  0 to 65 °C
Temperature Coefficient:  <0.2 % / °C

Acquisition Settings:
Gain:  3x; 0.1 V / (µg/l)
Internal low-pass filter of 0.1 second time constant
Data logged at 10 second intervals, no averaging