RBRtridente (tri)

The RBRtridente is an optical sensor with three channels, capable of making multiple fluorescence and backscatter or turbidity measurements simultaneously.

A dry-bay variant, designed for vehicle integration applications, offers the same channel options as the standard, wet-bay version. Fig. 30 shows an RBRtridente clamped on an RBRconcerto3.

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Fig. 30.    An RBRconcerto3 C.T.D.ODO.tri with RBRtridente

The RBRtridente uses multiple gains, allowing exposure to full sunlight. However, when exposed to high background ambient light, the resolution of some channels may decrease. For this reason, during deployments, orient the RBRtridente facing downwards to avoid exposure to direct sunlight. If you have to deploy it horizontally, ensure that the machined mark (see Fig. 31) is on top, so that detectors are facing down into the water column.
tridenteMark.png
Fig. 31.    An RBRtridente, note the machined mark above the detectors.

Optical

Parameter Value

Centroid angle

120°

Sensing volume

~1.3mL

Linearity, R2

0.99

Initial accuracy

5%

Chlorophyll a

Parameter Value

Channel wavelength
(excitation/emission)

470nm/695nm or
435nm/695nm

Calibrated range1

0-50µg/L

Measurement range

0-500μg/L

Detection limit1

0.010µg/L

1 Scaled for the in vivo fluorescence response.

fDOM1

Parameter Value

Channel wavelength
(excitation/emission)

365nm/450nm

Calibrated range

0-500ppb

Measurement range

0-1500ppb

Detection limit

0.030ppb

1 fDOM can be used as a proxy for cDOM.

Phycocyanin

Parameter Value

Channel wavelength
(excitation/emission)

590nm/654nm

Calibrated range

0-500µg/L

Measurement range

0-10000μg/L

Detection limit

0.200µg/L

Phycoerythrin

Parameter Value

Channel wavelength
(excitation/emission)

525nm/600nm

Calibrated range

0-6000µg/L

Measurement range

0-10000μg/L

Detection limit

2.0µg/L

Rhodamine

Parameter Value

Channel wavelength
(excitation/emission)

550nm/600nm

Calibrated range

0-1000µg/L

Measurement range

0-1000μg/L

Detection limit

0.015µg/L

Fluorescein

Parameter Value

Channel wavelength
(excitation/emission)

470nm/550nm

Calibrated range

0-500µg/L

Measurement range

0-1500μg/L

Detection limit

0.010µg/L

Backscatter

Parameter Value

Channel wavelength

470nm, 525nm, 650nm, or 700nm

Calibrated range1

0-0.05m-1sr-1

Measurement range

0-1.5m-1sr-1

Detection limit

1x10-6m-1sr-1

1 Response becomes non-linear above 0.05m-1sr-1.

Turbidity

Parameter Value

Channel wavelength

650nm or 700nm

Calibrated range1

0-500FTU

Measurement range

0-1500FTU

Detection limit

0.001FTU

1 Response becomes non-linear above 500FTU.

For highest accuracy, turbidity measurements require pressure correction. If installed on a moored instrument with no pressure sensor, enter the known depth value manually in the table under the Parameters tab in Ruskin.

Calibration equations

Chlorophyll a

\[Chl_{(\mu g/L)}=(C_0+C_1*V_r)*C_2\]

fDOM

\[fDOM_{(ppb)}=C_0+C_1*V_r\]

Phycocyanin

\[\text{Phycocyanin}_{(\mu g/L)}=(C_0+C_1*V_r)*C_2\]

Phycoerythrin

\[\text{Phycoerythrin}_{(\mu g/L)}=(C_0+C_1*V_r)*C_2\]

Rhodamine

\[\text{Rhodamine}_{(\mu g/L)}=C_0+C_1*V_r\]

Fluorescein

\[\text{Fluorescein}_{(\mu g/L)}=C_0+C_1*V_r\]

Turbidity

\[Tu_{(FTU)}=C_0+C_1*V_r\]

Backscatter

\[BB_{(m-1sr-1)}=C_0+C_1*V_r\]