Janko Drnovsek METROLOGY AND ENVIRONMENT gathering and sharing/Janko... · of Metrology and Quality...

University of LjubljanaFaculty of Electrical Engineering

Laboratoryof Metrologyand Quality

Prof Janko Drnovšek and Laboratory of Metrology and Quality group

Faculty of Electrical EngineeringUniversity of Ljubljana

[email protected]

Bridging the GapResponding to Environmental Change: from Words to Deeds

14-16 May 2008, Portorož

Metrology and Environment



Basic dilemmaHow to ensure appropriate environmental measurements and monitorenvironmental/climate changes?



Definitions

Metrology – science of measurementmeasurement - process of empirical, objective, assignment of numbers to properties of objects or events of the real world in such a way as to describe them

Testing – action of carrying out teststest – technical operation that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure

Monitoring – continuous observation (measurements and testing included)

Resolution - smallest difference between indications of a displaying device that can be meaningfully distinguished

Uncertainty - parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand

Sensitivity – change in the response of a measuring instrument divided by the corresponding change in the stimulus



Main objectives for environmental measurements

1. Comparable and reliable measurement results in time and space

2. Sensitivity of the measurement method (fitness for purpose)

3. “Resolution” versus “uncertainty”

4. A complete measurement result, including correction and uncertainty, should correspond to the required precision of observation



Copacabana, Rio de Janeiro, Brasil Portorož, Slovenia

TemperatureRelative humidity

Air pressureOzone concentration

…


Air pressureOzone concentration

…

InternationalIntercomparison

2008




Copacabana, Rio de Janeiro, Brasil Portorož, Slovenia



Air pressure…


Air pressure…

InternationalIntercomparison

1930196019802008



10 years 20 years 30 years

10 m

100 m

300 m

1000 m

2000 m

5 m

sea

dept

h

comparabilitytime invariance

traceability



Case study : Monitoring of seawater temperature changes - depth (vertical profile)


Required sensitivity = 5 °C/ 200 m = 0,025 °C/mRequired resolution = 0,020 °C

Uncertainty = 0,010 °C

Vertical profile (1 m)

Required sensitivity = 5 °C/ 200 m = 0, 25 °C/10mRequired resolution = 0,20 °C


Vertical profile (10 m)



Case study : Monitoring of seawater temperature changes - time (environmentalchanges)


Required resolution = 0,50 °C Uncertainty for ENTIRE time of observation = 0,10 °C



DEEP SEA PROBES

• depths to 1000 meters• uncertainty 0,1 °C • on buoys

Depth temperature profile measurements



INTERNATIONALCOMPARISONS

deep sea water temperature changes monitoring

NATIONALSTANDARDS

CALIBRATION LABORATORY

trac

eabi

lity




diss

emin

atio

n




time

temperature

resolution = 0.005 °C

uncertainty = 0.1 °Cupper limit

resolution is important!

definedalarmreal

alarm

Resolution of thermometer = 0.005 °C



time

temperature

resolution = 0.1 °C

uncertainty = 0.1 °Cupper limit

resolution is important!

definedalarmfalse

alarm

Resolution of thermometer = 0.1 °C



tem

pera

ture

t em

pera

ture

uncertainty = 1 °C

uncertainty = 0,1 °C

time10 years

10 years

30 years

30 yearstime



examples of different test result interpretation

WITHIN TOLERANCESOUTSIDE TOLERANCES OUTSIDE TOLERANCES

distribution ofmeasurements

real value ofmeasurement

real value ofmeasurement

upper limitlower limit

possibility of rejection ofan acceptableproduct/result

possibility of acceptance ofan unacceptableproduct/result



BIPM

Regional key interlaboratory comparisons

CIPM Key interlaboratory comparisons

National metrology institutes

= CIPM key-comparisons

= CIPM and Regional key-comparisons

= Regional key-comparisons

= BIPM key-comparisons = Bilateral key-comparisons

= MRA members



Interlaboratory intercomparison scheme



Hierarchical structure of technical infrastructure

National measuring standards

National metrology infrastructure

Testing

Standardisation

Accreditation

Certification

International trade

Traceability

MetrologyTesting

Standardisation

Accreditation

Certification



Acceptable measurement traceability

• VIM definition of traceability:Property of the result of a measurement or the value of standard whereby it can be related to stated

references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties.

• Traceability in national accreditation bodies:- Traceability is always related to accredited calibration laboratories (certificates)- Calibration certificates without accreditation logo are not accepted

Measuring instrument

Measurement result?



influential parameters:• influential parameter0 (uncertainty of the thermometer),• influential parameter1 (resolution of thermometer),• influential parameter2 (hydrostatic pressure),• influential parameter3 (currents),• influential parameter4(hot-water sources),• influential parameter5 …

...rl_parameteinfluentiarl_parameteinfluentiarl_parameteinfluentia 23

22

21 ++=u

u - uncertainty of the measurement result



Conclusions

! resolution IS NOT! uncertainty

! monitoring requires absolute accuracy in time and space

! absolute accuracy of measurement is the responsibility of national metrology infrastructure

• environmental monitoring and management depend on metrology !

Janko Drnovsek METROLOGY AND ENVIRONMENT gathering and sharing/Janko... · of Metrology and Quality...

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