Metrology and Environment

Transcription

1 Bridging the Gap Responding to Environmental Change: from Words to Deeds May 2008, Portorož Metrology and Environment Prof Janko Drnovšek and Laboratory group

2 Basic dilemma How to ensure appropriate environmental measurements and monitor environmental/climate changes?

3 Definitions Metrology science of measurement measurement - 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 tests test 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

4 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

5 1. Comparable and reliable measurement results in time and space International Intercomparison Temperature Relative humidity Air pressure Ozone concentration Temperature Relative humidity Air pressure Ozone concentration 2008 Copacabana, Rio de Janeiro, Brasil Portorož, Slovenia

6 1. Comparable and reliable measurement results in time and space International Intercomparison Temperature Relative humidity Air pressure Temperature Relative humidity Air pressure Copacabana, Rio de Janeiro, Brasil Portorož, Slovenia

7 sea depth 5 m 10 m 100 m 300 m 1000 m 2000 m 10 years 20 years 30 years traceability comparability time invariance

8 2. Sensitivity of the measurement method (fitness for purpose) Case study : Monitoring of seawater temperature changes - depth (vertical profile) Vertical profile (1 m) Required sensitivity = 5 C/ 200 m = 0,025 C/m Required resolution = 0,020 C Uncertainty = 0,010 C Vertical profile (10 m) Required sensitivity = 5 C/ 200 m = 0, 25 C/10m Required resolution = 0,20 C Uncertainty = 0,1 C

9 2. Sensitivity of the measurement method (fitness for purpose) Case study : Monitoring of seawater temperature changes - time (environmental changes) Required resolution = 0,50 C Uncertainty for ENTIRE time of observation = 0,10 C

10 Depth temperature profile measurements DEEP SEA PROBES depths to 1000 meters uncertainty 0,1 C on buoys

11 INTERNATIONAL COMPARISONS Uncertainty = 0,005 C traceability NATIONAL STANDARDS CALIBRATION LABORATORY Uncertainty = 0,010 C Uncertainty = 0,05 C dissemination deep sea water temperature changes monitoring Uncertainty = 0,1 C

12 resolution is important! Resolution of thermometer = C temperature resolution = C upper limit uncertainty = 0.1 C real alarm defined alarm time

13 resolution is important! Resolution of thermometer = 0.1 C temperature resolution = 0.1 C upper limit uncertainty = 0.1 C false alarm defined alarm time

14 temperature uncertainty = 1 C 10 years 30 years time temperature uncertainty = 0,1 C 10 years 30 years time

15 examples of different test result interpretation lower limit real value of measurement upper limit real value of measurement distribution of measurements possibility of rejection of an acceptable product/result possibility of acceptance of an unacceptable product/result OUTSIDE TOLERANCES WITHIN TOLERANCES OUTSIDE TOLERANCES

16 Interlaboratory intercomparison scheme Regional key interlaboratory comparisons BIPM CIPM Key interlaboratory comparisons Regional key interlaboratory comparisons Regional key interlaboratory comparisons National metrology institutes = CIPM key-comparisons = Regional key-comparisons = BIPM key-comparisons = Bilateral key-comparisons = CIPM and Regional key-comparisons = MRA members

17 Hierarchical structure of technical infrastructure National measuring standards National metrology infrastructure Traceability Testing Standardisation Accreditation Metrology Testing Standardisation Accreditation Certification Certification International trade

18 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

19 u - uncertainty of the measurement result u = 2 2 influential_parameter1 + influential_parameter2 + influential_parameter influential parameters: influential parameter0 (uncertainty of the thermometer), influential parameter 1 (resolution of thermometer), influential parameter 2 (hydrostatic pressure), influential parameter 3 (currents), influential parameter 4 (hot-water sources), influential parameter 5

20 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!