ENV05: METROLOGY FOR OCEAN SALINITY AND ACIDITY

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1 Kck-off meetng EMRP ENV5 Ocean Metrology - Setember, PB Berln ENV5: MEROLOGY FOR OCEAN SALINIY AND ACIDIY WP: Extenson of measurement range for thermohyscal arameters (INRM, PB) ISIUO MEROLOGICA Smona Lago INRM Steffen Rudtsch PB

2 Labour Resources: - PB - INRIM 3- IPQ 4- JRC 5- LNE 6- SYKE 7- MKEH WP NPL 9- SMU - U - UoP OAL Start month: Setember, End month: August 4 he man ams of the WP are: accurate exermental seed of sound measurements n seawater as functon of temerature ( C u to 4 C), ressures u to 7 MPa and salnty between 4 and 4 n-stu measurements of temerature and seed of sound hese nformaton are needed for further mrovements of the Equaton of State of seawater and to resolve exermental dscreances of hgh ressure seed of sound data. Dfferently from now avalable thermohyscal roertes data, those obtaned n ths WP wll refer to 8 dfferent Practcal Salnty values reared n WP (ask. - D..). ISIUO MEROLOGICA

3 Summary of Delverables for WP ask.: Start month Setember, End month Arl 4 Seed of sound measurements for metrologcal characterzaton of seawater (INRM, PB) Delverable number D.. D.. Delverable descrton Exermental devce comatblty wth chemcal characterstcs of SW tested estng of the exermental setu for the hase comarson method fnshed D..3 SoS results ( C < t < C, < < 7 MPa) D..4 SoS results ( C < t < 4 C, < < 7 MPa), D..5 D..6 Paer about SoS data as a functon of, and S submtted to a eer-revewed ournal Reort on methodology for nstu SoS determnatons submtted to a trade ournal Lead Partcant Other Partcants Delverable tye Delvery date INRM - Reort October PB - Reort October 3 INRM PB Data set December 3 INRM PB Data set February 4 INRM PB Publcaton Arl 4 PB INRM Reort Arl 4 ISIUO MEROLOGICA

4 Summary of Delverables for WP ask.: Start month Arl 3, End month August 4 Determnaton of thermohyscal roertes of Seawater (INRM) Delverable number D.. D.. Delverable descrton Comarson data between the seed of sound results obtaned by INRM and PB and nowadays avalable Equaton of state obtaned Paer about thermohyscal roertes of seawater obtaned from exermental measurements submtted to a eer-revewed ournal Lead Partcant Other Partcants Delverable tye Delvery date INRM - Data set, reort March 4 INRM - Publcaton August 4 ISIUO MEROLOGICA

5 Summary of Delverables for WP ask.3: Start month: Setember, End month: August 4 Imroved n-stu measurements of temerature and seed of sound (PB, INRM) Delverable number D.3. Delverable descrton Calbraton setu for drect nstu SoS sensor s buld Lead Partcant Other Partcants Delverable tye Delvery date PB - Reort October D.3. D.3.3 D.3.4 D.3.5 D.3.6 ISIUO MEROLOGICA Sensor for drect n-stu SoS measurements s tested Determnaton of uncertanty contrbutons of n-stu measurements of electrcal conductvty, temerature, and densty (CD) of ocean water erformed Metrologcal analyss of the uncertanty of drect SoS measurements, keeng nto account all the contrbutng arameters done Paer about self calbratng temerature sensors submtted to a eer-revewed ournal Gude for mroved n-stu measurements of oceanc temeratures done PB - Reort February 3 PB - Reort Arl 4 INRM PB Reort Arl 4 PB - Publcaton August 4 PB INRM Good Practce Gude August 4

6 ask.: Seed of sound measurements for metrologcal characterzaton of seawater (INRM, PB) he am of ths task are measurement results of seed of sound n seawater n a wde range of temerature ( C u to 4 C), ressures u to 7 MPa and salnty between 4 and 4 by means of an ultrasonc double-reflector ulseecho technque. Because of the large mact of accurate seed of sound data, the results wll be comared, at secfc temeratures and salntes, wth those obtaned at ambent ressure by a hase-comarson method. hs task wll enable to obtan accurate seed of sound values as a functon of the salnty, wth an uncertanty of about. % over the ranges secfed above. ISIUO MEROLOGICA

7 Measurement technque : Pulse-Echo method FUNCION GENERAOR (snusodal burst) 5 MHz L L PZ u t t t OSCILLOSCOPE L eco eco 3 eco 4 eco Frst Pulse L = w L = w(t - ) L = wt Second Pulse L = w L = w(t - ) L = wt w ex ( L L) L ( t t ) w ex = exermental seed of sound = delay between the two echoes L = dfference between the acoustc ath-lengths ISIUO MEROLOGICA

8 Ambent ressure lqud vessel Needle valve Pressure amlfers Mechancal manometer Vacuum um connector Pressure transducer Exermental Aaratus Ch Ch Lqud bath thermostat Hgh ressure lqud vessel 4 Ultrasonc cell 3 5 P I D Seral GPIB ISIUO MEROLOGICA

9 Ambent ressure lqud vessel Resstance brdge Osclloscoe Functon generator Exermental Aaratus Dewar Pressure amlfer Vacuum um ISIUO MEROLOGICA

10 u, m s- Seed of sound measurements n ure Water u, m s - emerature, K a b K 7 36 u, m s c em eratu re, K P res su re, M P a d ressure, MPa. MPa 9 MPa 74 K K 89 K 34 K 39 K 334 K 349 K 364 K 379 K 394 K ISIUO MEROLOGICA ressure, M Pa em erature, K. MPa MPa MPa 3 MPa 4 MPa 5 MPa 6 MPa 7 MPa 8 MPa 9 MPa

11 Estmated Uncertanty for ure Water w w L,,, meas w L w w meas w meas L wmeas wmeas Uncertanty Source Relatve Magntude Determnaton of the acoustc ath L L.6 % Determnaton of temoral delay. % emerature measurements Pressure measurements w w w w.3 %.3 % Estmated Overall Uncertanty <.5 % ISIUO MEROLOGICA

12 Devatons of w ex from w IAPWS-95 for ure Water IAPWS-95 4 (u ex - u IAPW S-95 )/ u IAPW S IAPWS K 89 K 34 K 39 K 334 K 349 K 364 K 379 K 394 K ressure, MPa ISIUO MEROLOGICA

13 Very relmnary SoS measurements n Standard Seawater (s = 35 ): Problem!!! After strrng ISIUO MEROLOGICA

14 Estmated Uncertanty for Standard Seawater (s = 35 ) wex w L,,,, s Uncertanty Source Relatve Magntude Determnaton of the acoustc ath L L.4 % Determnaton of temoral delay emerature measurements Pressure measurements Salnty/Comoston. % u u u.3 % u. % S S.3 % Estmated Overall Uncertanty.5 % ISIUO MEROLOGICA

15 Devatons of w INRM from w EOS- [] for Seawater EOS- uncertanty (.5%) ISIUO MEROLOGICA [] IAPWS Formulaton 8 for the hermodynamc Proertes of Seawater (SIA Lbrary)

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17 ask.: Determnaton of thermohyscal roertes of Seawater (INRM) Defnng the Equaton of State of seawater s fundamental for many actvtes concerned wth observng the hyscal state of the oceans and reresentng ocean rocesses n numercal models. he characterzaton of seawater can rovde a metrologcal suort to the analyss and redcton of global clmate change. he thermodynamc quanttes measured wll be merged together wth the am to calculate those roertes that are not drectly accessble by exermental measurements, but that can lay a fundamental role n the modellng comlex systems nvolvng seawater. INRM wll mlement an emrcal Equaton of State of Seawater, as a functon of temerature, densty and salnty, based on analytcal thermodynamc relatonshs, and lmted to the lqud hase. ISIUO MEROLOGICA

18 ISIUO MEROLOGICA = densty c = sobarc secfc heat caacty = thermal exanson coeff. S = entroy w c c In a flud, there are quanttes that are very useful both for mlementng and for checkng the redctons of ts equaton of state (EoS). In artcular, asde from densty and vaor ressure, seed of sound s the next most mortant roerty for develong excellent equatons of state (more accurate the SoS data are, more accurate the EoS wll be). S w, Seed of sound as thermodynamcal quantty Intal condtons: ), ( );, ( c Among dfferent ways to obtan the thermodynamc roertes (and EoS) of a flud n lqud hase, there s the ossblty to solve a system of two dfferental equatons, where densty and secfc heat caacty are the unknown varables, exressed as functons of temerature and ressure.

19 hermodynamc roertes from seed of sound measurements Advantages of ths aroach: few ntal condtons ermt to determne ndrectly the thermodynamc roertes n a wde range of temerature and ressure, wth a good accuracy (comarable wth that obtaned by drect measurements), usng the seed of sound data as control onts for the algorthm of mlementaton. n lquds, drect accurate measurements of quanttes lke densty or, esecally, secfc heat caacty become extremely dffcult n condtons of hgh ressure, as consequence ths method results artcularly attractve. Moreover, wth a comlete knowledge of densty and sobarc heat caacty as a functon of temerature and ressure, all other observable thermodynamc roertes can then be calculated, ncludng: ISIUO MEROLOGICA Adabatc comressblty, S hermal exanson coeffcent, Isothermal comressblty, Isochorc heat caacty, c v w S w c c v c

20 Recursve Equaton Method he REM method s based on the resoluton of recursve equatons, by means of (,,s) and c (,,s) known at reference ressure, as a functon of the temerature, consderng known the seed of sound functon w(,,s), at least over a temerature and ressure range. Usng a mxed ntegraton method, analytc and numercal, t s ossble to determne the felds (,,s) and c (,,s) over the same doman of w(,,s). he am s to mrove the accuracy of the determnatons of the unknown functons values, n artcular those ones near the boundary of the ntegraton range and to make a detaled statstcal analyss of the arameters obtaned by fttng and to evaluate the consequent uncertanty roagaton on the calculated coeffcents. B-dmensonal Polynomal Functon N M L w(,, s) w ( ) ( ) ( s s ), l l,, l where N = olynomal degree, M = olynomal degree, L = s olynomal degree, w,,l = unknown arameters Alyng the seed of sound olynomal functon w(,,s) to our exermental row data N M L w u(,, s ) w ( ) ( ) ( s s ) l k k k k,, l k k k l Least-Squares Regresson Method Lookng for the best arameters w,,k that mnmze the ( ) functon n order to obtan a contnuous w(,,s) functon w,, k ISIUO MEROLOGICA

21 Recursve Equaton Method Dfferently from the most wdesread algorthm, the recursve equaton method exects that the mathematcs form of the solutons s establshed a ror and t has been chosen to make use, also for and c, of a bvarate olynomal functon he necessary frst and second dervates have been calculated: N M (, ) a, ( ) ( ), N M (, ) ( ) a, ( ) ( ), N M c (, ) b ( ) ( ), N M w(, ) w ( ) ( ), N M, (, ) a ( ) ( ),, N M, c (, ) b ( ) ( ) Rewrtng the revous equatons system: c w w c, c 3 and the coeffcents regardng the ntal condtons (one-dmensonal olynomal ft): ISIUO MEROLOGICA M (, ) a ( ),, M, c (, ) b ( ) a we obtan the solutons of the recursve equatons for the unknown arameters a, and b, of the system as a functon of the terms a,, b, and w,, : a,, w, b, a, e b, a,, 3, a a a,

22 ISIUO MEROLOGICA REM - Isobarc secfc heat caacty determnaton Usng REM, sobarc secfc heat caacty c (,) can be calculated n a wde - range also startng only by means of seed of sound w(,) and densty (,), as nut data. w c c ), ( w c calculated usng: M a ) ( ) ( N b ) ( ) ( calculated usng: M a ) ( N b ) ( N M w w ) ( ) ( ), (, N M a ) ( ) ( ), (,,, ), ( w b a a c REM allows a detaled statstcal analyss of the arameters and the consequent evaluaton of the uncertanty roagaton on the calculated coeffcents

23 Results of sobarc secfc heat caacty for ure water: Comarson wth the dedcated EoS [] NIS uncertanty 3 K 3 K 3 K 33 K 34 K 35 K (c NIS -c INRIM )/c NIS / MPa ISIUO MEROLOGICA [] NIS Reference Flud hermodynamc and ransort Proertes Database (REFPROP): Verson 9.

24 ask.3: Imroved n-stu measurements of temerature and seed of sound (PB, INRM) Currently the n-stu determnaton of the seed of sound of ocean water s mostly carred out ndrectly. Seed of sound s calculated from measurements of electrcal conductvty, temerature and densty (CD). he am s to comare ths methodology wth drect seed of sound measurements on the bass of a comlete uncertanty analyss. - PB wll determne the uncertanty contrbutons of n stu measurements of electrcal conductvty, temerature and densty of ocean water; wll delver a self calbratng scheme for temerature sensors; wll mrove the n-stu determnaton of temerature and seed of sound by CD measurements and wll test a sensor for n-stu seed of sound measurements. - INRM wll carry on a detaled metrologcal analyss of the uncertanty of drect seed of sound measurements obtaned n ask. keeng nto account all contrbutng arameters and wll suort the uncertanty comarson between CD seed of sound values. ISIUO MEROLOGICA

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27 Conclusons wo dfferent exermental aaratuses (ulse-echo and hase comarson) wll be set-u n order to obtan a metrologcal themodynamc characterzaton (EoS) of seawater, by means of accurate exermental seed of sound w(,,s) measurements, over an extended regon of s sace. A new method for the determnaton of the thermodynamcal roertes of fluds, based on the combnaton between exermental acoustc measurements and seres ntegraton methods, has been descrbed. he Recursve Equatons Method s based on the resoluton of recursve equatons, for the determnaton of the densty (,,s) and sobarc secfc heat caacty c (,,s) functons, usng the w(,,s) exermental values and the ntal values of densty (,,s) and sobarc secfc heat caacty c (,,s) known at reference ressure, as a functon of temerature. Moreover, an alcaton of REM method has been resented. It ermts an accurate themodynamcal characterzaton of lquds (EoS), by means of only seed of sound w(,,s) and densty (,,s) nut data, as a functon of temerature, ressure and salnty. Develoment of a methodology for mroved temerature measurements, by mroved sensor annealng and more accurate and traceable calbratons. Develoment of a measurement set-u for the calbraton of n-stu seed of sound sensors. ISIUO MEROLOGICA

28 ISIUO MEROLOGICA hank you for your knd attenton!