Calculation method of flux measurements by static chambers

Transcription

1 lculion mehod of flux mesuremens by sic chmbers P.S. Kroon Presened he NiroEurope Workshop, 15h - 17h December 28, openhgen, Denmrk EN-L December 28

2 lculion mehod of flux mesuremens by sic chmbers Per Kroon 1,2 1. EN, Neherlnds ; 2. TU Delf, Neherlnds

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4 Wh s he mos pproprie mehod? Wh s he quliy of liner mehod?

5 Ouline Theoreicl models Simplified models omprison of he models Argumens for liner model Quliy of chmber clculion mehods Summry nd recommendions

6 z zz Soil Mrix Theoreicl models s Flux J g Source λ ollr 1D diffusion equion Mss blnce F c V A D Resercher s J g λ De Mello nd ir onsn J g onsn Hines 1994 Go e l onsn J g onsn onen nd Smih 2 Livingson e l. 26 d d 2 z 2 + λ z ir s J onsn g s s J g λz s

7 Theoreicl models De Mello nd Hines 1994, JGR A V h h J A V h c s c g c s s / exp / exp s c c g c h F d d h J F Go nd Yes 1998, JGR A V h h J A V h c s c g c s / exp / exp 1 s c c g c h F d d h J F h h c θd Wih soil m ir m 3 3 > θ

8 Theoreicl models Generl behviour of models bsed on Go nd Yes 1998 nd De Mello nd Hines 1994 Go nd Yes

9 Theoreicl models Generl behviour of models bsed on Go nd Yes 1998 nd De Mello nd Hines > s & J g Go nd Yes

10 Theoreicl models onen nd Smih 2, Europen Journl of Soil Science Resercher s J g λ De Mello 1994 ir onsn J g onsn Go 1998 onsn J g onsn onen 2 ir s J onsn g Livingson 25 s s J g λz s

11 Theoreicl models onen nd Smih 2, Europen Journl of Soil Science

12 Theoreicl models onen nd Smih 2, s Europen Journl of Soil Science J h g c

13 Theoreicl models onen nd Smih 2, s Europen Journl of Soil Science J h g c -> s & J g

14 Theoreicl models Livingson e l. 26, Soil science sociey of Americ journl Resercher s J g λ De Mello 1994 ir onsn J g onsn Go 1998 onsn J g onsn onen 2 ir s J onsn g Livingson 26 s s J g λz s τ τ + J τ / τ + e erfc / τ V / A h c o A V 2 / π

15 Theoreicl models Differences in heoreicl models: Assumpions -> differen equions for nd J g Resercher s J g λ De Mello nd Hines 1994 ri onsn J g onsn Go e l onsn J g onsn onen nd Smih2 ir s J onsn g Livingson e l. 26 s s J λz g s Similriy in heoreicl models: J g is no consn No lekge ken ino ccoun No vegeion ken ino ccoun

16 Theoreicl models Kuzbch e l. 27, Biogeosciences: Lek exp Lek exp K k d D p B p p p A V d d A V F p p p f c F F F F F p c R p soil c ε ε

17 Simplified models Liner model: e.g. Ruser e l. 1998; Hendriks e l. 27 Qudric model: e.g. Wgner e l H-M model: e.g. Huchinson nd Mosier, 1984 b f c lin ε ε qu c b f c ε ε nd for ln > A V F c c d d A V F Anhony e l. 1995

18 Simplified models Slope-inercep model: Kroon e l Exp Lin 95 d d i i i i 1 i 1 i 1,2,.., N 1 [ppb] [s] 9 J F g c J f + ε h. + b + h. ε g lin h. d/d [ppb/sec] 6 3 Exp Lin [s]

19 omprison of he models Liner versus De Mello nd Hines 1994 s s h c c + b exp V / A Bsed on mesuremens buw in he Neherlnds umlin/umexp: 69% nd 63% Kroon e l

20 omprison of he models Liner versus onen nd Smih 2 c + b Bsed on model J i 1 i i V A p Lin flux/rel flux rnge: 72% nd 99% onen nd Smih

21 omprison of he models Inercep versus De Mello nd Hines 1994 d i i 1 s h s c i 1,2,.., N 1 exp d i i i 1 V / A. Fc J g h. + b Bsed on mesuremens buw in he Neherlnds F c J g d h d Kroon e l

22 omprison of he models Wh s he mos ccure model? Deerminion by goodness-of-fi nlyses 2 χ N yi ŷi i 1 2 Livingson e l. 26 Kroon e l. 28 Flux difference dependen on: τ V / A h c

23 Why do mos of he people sill use liner regression? Possible resons: Assumpion h conenrion behviour is liner over shor mesuremen imes. Assumpion h non-liner concenrion behviour cn only be cused by lekge. Assumpion h unceriny due o spil nd emporl vriion is much lrger hn he bises due o liner regression

24 Assumpion I: Shor mesuremen imes Kroon e l

25 Assumpion II: Non-lineriy cn only occur due o lekge Bsed on heoreicl Go model wihou lekge Go nd Yes

26 Assumpion III: Unceriny due o spil nd emporl vriion is much lrger hn bises due o liner regression

27 Why do mos of he people sill use liner regression? Possible resons: Assumpion h conenrion behviour is liner over shor mesuremen imes. Assumpions re no definiely ruh! Assumpion h non-liner concenrion behviour cn only be cused by lekge. Assumpion h unceriny due o spil nd emporl vriion is much lrger hn he bises due o liner regression

28 Quliy of chmber clculion mehods Rochee nd Eriksen-Hmel

29 Quliy chmber clculion mehods Rochee nd Eriksen-Hmel

30 Quliy chmber clculion mehods Rochee nd Eriksen-Hmel

31 Summry There re severl sudies given in he lierure for clculing fluxes by sic chmbers. They re bsed on he mss equion nd diffusion equion. The models re bsed on differen ssumpions. However, hey ll indice h he fluxes re no consn. The concenrion behviour is dependen on he heigh of he chmber nd he ir filled porosiy. Underesimion increses wih decresing heigh nd incresing ir filled porosiy. There re severl simplified models for clculing fluxes by sic chmbers, like qudric, liner nd H-M model. These simplified models underesime he flux. The moun of underesimion cn be more hn 4%

32 Summry The liner mehod underesime he flux even for shor mesuremen imes nd wihou lekge of he chmber. Using n incorrec mehod led o sysemic underesimion which is very significn even in comprison wih he spil nd emporl vriion. The quliy of he flux esimion is dependen on he used model, he moun of mesuremen poins nd mesuremen ime

33 Recommendions A non-liner mehod should be used. ompre differen non-liner mehods using goodness-of-fi nlyses o choose he mos pproprie mehod. Mehod References Model vilble online Exp1 De Mello nd Hines 1994 Exp2 Go e l Exp3 Kuzbch e l. 27 X * NDFE Livingson e l. 26 X ** Slope inercep Kroon e l. 28 Amoun of mesuremen poins should be les 3. The heigh of he chmber should be les 4 cmhr -1. *hp://biogeo.bonik.uni-greifswld.de/index.php?id264 Lin&Non-liner **hp://rsgsofwre.rs.usd.gov Excell comprison Lin,Qu&NDFE

34 lculion mehod of flux mesuremens by sic chmbers Per Kroon 1,2 1. EN, Neherlnds ; 2. TU Delf, Neherlnds