A look into the future of direct comparison

ambient temperature salinometry

RBR Ltd, Ottawa, Canadainfo@rbr-global.com

With my AutoSalTM, can I:

1. Use it on a small boat? NO2. Transport it in my suitcase? NO3. Characterize different seawaters over temperature? NO4. Test the salinity of Guacamole? NO5. Run it off of a car battery? NO6. Set it up and use within 1 hour? NO

Salinometer FAQ

• Why Salinometry? • Standard Methods of Salinometry• Basic limitations• The future of Salinometry• Conclusion/Discussion

Outline

Why Salinometry?

Salinity is a key property of seawater from which density and sound speed may be derived; these

are fundamental to ocean science and climatology.

Salinometers provide a reference to the widely accepted Practical Salinity Scale.

CTD & Water Samples AutoSAL

Standard Method

Salinometer

referenced to

Standard Seawater

sequential samples

Standard Method - Standardization

• Temperature stabilized environment• Sequential standardization• Skilled staff • SSW is expensive• Warming samples may change apparent salinity

Limitations

- High Performance- Easy to Use- Operates at in situ

temperatures - Small size

The Future…now

Concepts of the Small Salinometer:

1. Direct comparison of conductivity of sample and standard

2. Direct reading of Rt over wide temperature range

(a) China – Tienjin. in Collaboration with Tim Dauphinee, NSERC Canada

Two conductive cells

Previous works

(b) Ukraine – SevastopolInductive method

Dual chamberInductive system

Based on standard RBR technology

Dual Chamber principle

Sample Cell Reference Cell

Fluid outlets

Fluid inlets

Oil Bath

Concepts of the Small Salinometer:

1. Direct comparison of conductivity of sample and standard

2. Direct reading of Rt over wide temperature range

Salinometers measure Rt

Practical Salinity Scale - 1978

Test Results

MS-310 Repeatability Using Samples of Constant Salinity

21

22

23

24

25

10:32:00 12:00:00 12:48:00 13:36:00 15:14:00 16:15:00time

T °C

34.894

34.896

34.898

34.900

34.902

Salin

ity p

su

TemperatureSalinity

Calibration of Temperature Sensor

Test Results

Residuals Versus Temperature

-0.0010

-0.0005

0.0000

0.0005

0.0010

0 5 10 15 20 25 30 35

Temperature °C

Res

idua

ls °

C

Rt variation with temperature for samples of Standard SeawaterTest Results

MS-310 and AutoSal 8400B against OSIL Linearity pack (1 trial)

Test Results

Figure 4. D298 Autosal and MS-310 standardization drift

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

1 2 3 4 6 8 12 16 19 22 25 27 30 32 35 39 42 45 47 50 53 56 60 63

Station numbers

dS=S

ssw

(end

)-Sss

w(s

tart

), PS

S-78

Autosal drift MS-310 drift

Salinometer Drift Comparison

Performance data compared with PortaSal and AutoSal

AutoSal 8400B

PortaSal 8410A

MicroSal MS-310

Range0.0001 to

1.150.0001 to

1.150.0001 to

2.00 Rt

Accuracy 0.002 0.003 0.002 psu

Resolution 0.0002 0.0003 0.0002 Psu

Room Temp +0°; -2° +0°; -2° 15° to 30° C

Bath 16.8 9 2 Litres

Weight 70 29 5 kg

Power 400 200 10 watts

Supply Voltage 110/220 AC 110/220 AC 12 DC volts

MS-310 User Interface

Windows®-based control panel streamlinesAnd simplifies operation

Easy to use

• 280mm x 280mm x 180mm• 5kg• 12VDC

Small Size

What else can I do with the MS-310?

• Thermosalinograph• Measure other fluids (guacamole?)• Immerse in bath for direct calibration of CTDs• Autosamplers• Submersible ocean salinometer (ZEFICC) • Investigate behaviour of seawater types

Dec06-Jan07 Different waters vs IAPSO SSW Salinity-Temperature test residuals

-0.0300

-0.0200

-0.0100

0.0000

0.0100

0.0200

0.0300

0.0400

0.0500

0 5 10 15 20 25 30

Temperature, deg.C

dS=S

sam

ple-

Sssw

, PSS

-78

SSW Pacific seawater Test bath Salt water PEI seawater

Characterization of various seawater types over temperature range

The MS-310 represents the future of scientific salinity measurement, allowing measurement of salinity samples directly after CTD retrieval, outside the lab; the nearest thing to in situ salinometry.

This offers a new perspective for understanding the nature of the conductivity measurements of seawater and opens doors beyond the PSS-78.

Water samples should not have to be adjusted to a salinometer’s comfort conditions, rather the salinometer should adjust to the CTD measurement

conditions – this is the future of salinity technology

Conclusions