B13E-0583 MiMeasuringlklake-air CHi CH CO and Hd H O fl ith … · B13E-0583 MiMeasuringlklake-air...
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B13E 0583 M i lk i CH CO d H O fl ith th di t diff i th d B13E-0583 Measuring lake-air CH CO and H O fluxes with the gradient diffusion method Measuring lake-air CH 4 , CO 2 and H 2 O fluxes with the gradient diffusion method 4 2 2 W i Xi 1 Xhi L 12 Sh d Li 1 Wi W 1 H h Li 1 Qit Xi 1 Wei Xiao 1 Xuhui Lee 1,2 Shoudong Liu 1 Wei Wang 1 Hanchao Li 1 Qitao Xiao 1 Wei Xiao , Xuhui Lee , Shoudong Liu , Wei Wang , Hanchao Li , Qitao Xiao 1 Yale NUIST Center on Atmospheric Environment Nanjing University of Information Science & Technology Nanjing 210044 China; wei xiao@nuist edu cn 1 Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science & Technology, Nanjing 210044, China; wei[email protected] Yale NUIST Center on Atmospheric Environment, Nanjing University of Information Science & Technology, Nanjing 210044, China; wei[email protected] 2 School of Forestry and Environmental Studies Yale University New Haven Connecticut 06511 USA 2 School of Forestry and Environmental Studies,Yale University, New Haven, Connecticut 06511, USA School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA It d ti Introduction Introduction In order to measure the small G di t t In order to measure the small Gradient measurement Lakes are an important component of the global greenhouse gas fl t th lk t h Gradient measurement 2384 pb Lakes are an important component of the global greenhouse gas flux at the lake-atmosphere 2384 pp cycles Several methods are available for the measurement of lake air flux at the lake atmosphere p cycles. Several methods are available for the measurement of lake-air interface using the GD method 4 , fl f h h fl ti t ti h b t interface using the GD method, Filt H fluxes of greenhouse gases such as floating static chamber water we reduced turbulent Filter 2376 C fluxes of greenhouse gases, such as floating static chamber, water we reduced turbulent 2376 equilibrium method eddy covariance (EC) and gradient diffusion (GD) fl t ti ith b ff l equilibrium method, eddy covariance (EC) and gradient diffusion (GD). fluctuations with buffer volumes 424 m fluctuations with buffer volumes Flow meter Filter Gas intake 424 m M i th lk i h fl i h ll i f l and minimized the transient Flow meter Filter 424 pp Measuring the lake-air greenhouse gas fluxes is challenging for several and minimized the transient 1 5L/ i p Measuring the lake air greenhouse gas fluxes is challenging for several time between valve switching 1.5L/min 2 , reasons including small signal to noise ratios bubble ebullition that time between valve switching Bypas Gas intake Solenoid 423 O 2 reasons, including small signal to noise ratios, bubble ebullition that i ll d h tt b Bypas s Gas intake Solenoid 423 CO evades equilibrium method detection large density corrections on the using small and short tubes Flow meter s Pump C evades equilibrium method detection, large density corrections on the using small and short tubes. Flow meter Pump evades equilibrium method detection, large density corrections on the EC fl d i f ih h h b hd 1 5L/min 3.7 %v EC flux and wave interference with the chamber method 1.5L/min 3.7 % EC flux, and wave interference with the chamber method. A3 l it h d 4L O, % A3-way valve switched 4L B ff B ff O In this study a trace gas analyzer based on the cavity ring down A 3 way valve switched Analyzer Buffer Buffer 35 H 2 In this study, a trace gas analyzer based on the cavity ring-down between the two intakes every Analyzer 0.2L/min 3.5 H t (CRDS) l d i th GD d t th between the two intakes every 0.2L/min spectroscopy (CRDS) was employed in the GD mode to measure the 60 s and the measurement 11 53 43 11 55 43 11 57 44 11 59 47 12 01 50 spectroscopy (CRDS) was employed in the GD mode to measure the 60 s and the measurement 11:53:43 11:55:43 11:57:44 11:59:47 12:01:50 H O CO and CH fluxes at a lake atmosphere interface hd t d tt i l Ti DOY 227 H 2 O, CO 2 and CH 4 fluxes at a lake-atmosphere interface. approached steady state in less Time, DOY 227 2 2 4 approached steady state in less O td t b th fi t tt t t i th fl than 10 s after each switching Schematic design diagram of the gradient measurement system Step changes in the CO CH and H O mixing ratios in response to valve switching Our study appears to be the first attempt at measuring these fluxes than 10 s after each switching. Schematic design diagram of the gradient measurement system Step changes in the CO 2 , CH 4 and H 2 O mixing ratios in response to valve switching Our study appears to be the first attempt at measuring these fluxes simultaneously using one instrument and in a long term uninterrupted simultaneously using one instrument and in a long-term uninterrupted operation operation. Latent heat and CO flux comparison The goal of this paper is to present a performance evaluation of this Zero-gradient test Latent heat and CO 2 flux comparison The goal of this paper is to present a performance evaluation of this Zero-gradient test Latent heat and CO 2 flux comparison measurement system at Lake Taihu from May 11 to August 31 2012 measurement system at Lake Taihu from May 11 to August 31, 2012 160 500 40 60 30 160 EC all w ind direction 500 1200 40 60 30 140 EC, all w ind direction GD, all w ind direction 400 All w ind direction G dfth 30 y y y 140 EC, good fetch 400 Good fetch 1000 30 ncy 40 ncy 20 ncy 120 GD, good fetch 300 m -2 20 uen uen uen 120 -2 300 W m 800 cy 20 equ 20 equ 10 equ m - 200 , W enc 10 Fre 20 Fre 10 Fre 100 W 200 EC 600 que 10 Site and Instruments LE, 100 of E Freq 0 0 0 Site and Instruments 80 L 100 LE o 400 F -1 0 1 2 0 -0.2 0 0.2 0 -0.01 0 0.01 H O di t% 0 L CH 4 gradient, ppb CO 2 gradient, ppm H 2 O gradient, %v 60 0 200 4 2 Th i t it (31 o 24′N 120 o 13′E) i th th t fLk 100 60 30 60 The experiment site (31 o 24′N 120 o 13′E) was in the north part of Lake 0 4 8 12 16 20 24 40 -100 0 100 200 300 400 500 -100 100 0 100 200 300 400 500 0 The experiment site (31 24 N, 120 13 E) was in the north part of Lake 0 4 8 12 16 20 24 Time Hour 100 0 100 200 300 400 500 LE of GD W m -2 -100 0 100 200 300 400 500 LE f GD W 2 40 cy 20 cy 40 cy Taihu which is the third largest freshwater lake in China with a water Time, Hour LE of GD, W m 2 LE of GD, W m -2 40 enc 20 enc 40 en Taihu, which is the third largest freshwater lake in China, with a water que que 20 equ surface area of 2400 km 2 and a mean water depth of 1 9 m Wi d di ti f lli i th f 180 345 o id d 20 req 10 req 20 Fre surface area of 2400 km 2 and a mean water depth of 1.9 m. Wind direction falling in the range of 180-345 o was considered as 20 F 10 F F Wind direction falling in the range of 180 345 was considered as 0 good fetch wherein the signal was least interfered by land 0 05 0 0 05 0 20 10 0 10 20 0 -0.1 0 0.1 0.2 2 1 good fetch, wherein the signal was least interfered by land -0.05 0 0.05 CO fl -2 -1 -20 -10 0 10 20 LE W -2 CH 4 flux, g m -2 s -1 ecosystems CO 2 flux, mg m -2 s -1 LE, W m -2 4 A CRDS analyzer (Model ecosystems. A CRDS analyzer (Model Mixing ratio gradient 30-min Flux ecosystems. G1301 Picarro Inc CA Mixing ratio gradient 30 min Flux I i t th EC t th GD th d dd G1301, Picarro Inc., CA, In comparison to the EC measurement, the GD method recorded USA) dt H 2 O CO 2 CH 4 LE CO 2 flux CH 4 flux In comparison to the EC measurement, the GD method recorded USA) was used to H 2 O % CO 2 CH 4 b LE W 2 CO 2 flux 2 1 CH 4 flux 2 1 higher LE values under good fetch conditions indicating possible USA) was used to %v ppm ppb W m -2 mg m -2 s -1 μg m -2 s -1 higher LE values under good fetch conditions, indicating possible EC simultaneously measure bias errors in the Monin Obukhov turbulent diffusivity formulation EC simultaneously measure Mean value 7 36×10 -5 0 0332 0 203 0 231 0 00914 0 0214 bias errors in the Monin-Obukhov turbulent diffusivity formulation. GD the mixing ratio of CO Mean value -7.36×10 -5 -0.0332 0.203 -0.231 -0.00914 0.0214 the mixing ratio of CO 2 , Standard deviation 0 00202 0 0410 0 356 5 496 0 0113 0 0379 2 CH d H O Ai Standard deviation 0.00202 0.0410 0.356 5.496 0.0113 0.0379 01 600 CH 4 and H 2 O Air was 0.5 All i d di ti 0.1 600 CH 4 and H 2 O. Air was A di tt t f d ith th t itk iti d s -1 All w ind direction Good fetch drawn from two intakes at A zero-gradient test, performed with the two intakes positioned -2 s Good fetch 0.05 1 y 200 m drawn from two intakes at A zero gradient test, performed with the two intakes positioned m - 2 s - 400 cy http://ditu.google.cn th h i ht f11 d next to each other indicates very small bias errors mg 0 m -2 400 enc the heights of 1.1 m and next to each other, indicates very small bias errors. 0 C, m 0 mg m ue the heights of 1.1 m and 0 EC , m eq 3 5 m above the water of -0.05 ux 200 Fre GD EC 3.5 m above the water ux O 2 fl F surface and measurement 2 fl 01 CO EC, all w ind direction surface, and measurement CO -0.1 C GD, all w ind direction EC dfth 0 ti 1 i h 05 C EC, good fetch GD good fetch -0 1 -0 05 0 0 05 01 0 CH fl time was 1 min on each -0.5 0 0.5 -0.5 0 4 8 12 16 20 24 -0.15 GD, good fetch 0.1 0.05 0 0.05 0.1 2 1 CH flux time was 1 min on each 0.5 0 0.5 CO flux of GD mg m -2 s -1 0 4 8 12 16 20 24 Time Hour CO 2 flux of GD, mg m -2 s -1 CH 4 flux intake CO 2 flux of GD, mg m s Time, Hour 2 4 intake. 05 500 3 F th CO fl bi diff it bt th GD d th EC 0.5 1 All wind direction 500 3 -1 For the CO 2 flux obvious difference exists between the GD and the EC 04 s -1 Good fetch 400 2 s - A dd i t For the CO 2 flux, obvious difference exists between the GD and the EC 0.4 m -2 cy 2 m -2 An eddy covariance system method The EC system recorded negative flux in the daytime while g m 300 enc 1 g m An eddy covariance system method. The EC system recorded negative flux in the daytime, while 0.3 g que 1 g was installed at the same the GD method shows a weak positive flux 0.3 ux, 200 req 0 ux, was installed at the same the GD method shows a weak positive flux. 02 flu 100 F flu site ith a distance of 100 0.2 H 4 100 -1 H 4 site, with a distance of 100 Th diff i th CO fl h b db i th CH 0 CH site, with a distance of 100 f h GD i k The difference in the CO 2 flux may have been caused by errors in the 0 4 8 12 16 20 24 0.1 -1 -0 5 0 05 1 0 130 150 170 190 210 230 250 -2 m from the GD intakes The difference in the CO 2 flux may have been caused by errors in the Cf ff 0 4 8 12 16 20 24 1 0.5 0 0.5 1 CH flux of GD gm -2 s -1 130 150 170 190 210 230 250 DOY f 2012 m from the GD intakes. density corrections to the EC flux and by different algal activities within Time, Hour CH 4 flux of GD, g m s DOY of 2012 density corrections to the EC flux and by different algal activities within their respective source footprints CH flux was positive most of the time except for occasional their respective source footprints. CH 4 flux was positive most of the time except for occasional negative values at night negative values at night. Acknowledgement: This research was supported by the Natural Science Foundation of Jiangsu Province China (grant BK2010572) the Ministry of Education of China (grant PCSIRT) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (grant PAPD) Acknowledgement: This research was supported by the Natural Science Foundation of Jiangsu Province, China (grant BK2010572), the Ministry of Educat ion of China (grant PCSIRT) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (grant PAPD).
Transcript of B13E-0583 MiMeasuringlklake-air CHi CH CO and Hd H O fl ith … · B13E-0583 MiMeasuringlklake-air...
B13E 0583M i l k i CH CO d H O fl ith th di t diff i th d
B13E-0583Measuring lake-air CH CO and H O fluxes with the gradient diffusion methodMeasuring lake-air CH4, CO2 and H2O fluxes with the gradient diffusion methodg 4, 2 2 g
W i Xi 1 X h i L 1 2 Sh d Li 1 W i W 1 H h Li1 Qit Xi 1Wei Xiao1 Xuhui Lee1,2 Shoudong Liu1 Wei Wang1 Hanchao Li1 Qitao Xiao1Wei Xiao , Xuhui Lee , , Shoudong Liu , Wei Wang , Hanchao Li , Qitao Xiao, , g , g , , Q1Yale NUIST Center on Atmospheric Environment Nanjing University of Information Science & Technology Nanjing 210044 China; wei xiao@nuist edu cn1Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science & Technology, Nanjing 210044, China; [email protected] NUIST Center on Atmospheric Environment, Nanjing University of Information Science & Technology, Nanjing 210044, China; [email protected]
2School of Forestry and Environmental Studies Yale University New Haven Connecticut 06511 USA2School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USASchool of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA
I t d tiIntroductionIntroduction In order to measure the smallG di t t In order to measure the small Gradient measurement
Lakes are an important component of the global greenhouse gas fl t th l k t hGradient measurement 2384pb Lakes are an important component of the global greenhouse gas flux at the lake-atmosphere2384
ppp p g g gcycles Several methods are available for the measurement of lake air
flux at the lake atmosphere pcycles. Several methods are available for the measurement of lake-air interface using the GD method4,cyc es Se e a et ods a e a a ab e o t e easu e e t o a e afl f h h fl ti t ti h b t
interface using the GD method, Filt H
fluxes of greenhouse gases such as floating static chamber water we reduced turbulentFilter 2376Cfluxes of greenhouse gases, such as floating static chamber, water we reduced turbulent 2376
equilibrium method eddy covariance (EC) and gradient diffusion (GD) fl t ti ith b ff lequilibrium method, eddy covariance (EC) and gradient diffusion (GD). fluctuations with buffer volumes424m
q , y ( ) g ( ) fluctuations with buffer volumes Flow meterFilterGas intake 424m
M i th l k i h fl i h ll i f l and minimized the transientFlow meterFilter 424
pp Measuring the lake-air greenhouse gas fluxes is challenging for several and minimized the transient 1 5L/ i
p Measuring the lake air greenhouse gas fluxes is challenging for severaltime between valve switching
1.5L/min 2,
reasons including small signal to noise ratios bubble ebullition that time between valve switching BypasGas intake Solenoid 423O2
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t (CRDS) l d i th GD d t thbetween the two intakes every 0.2L/min
spectroscopy (CRDS) was employed in the GD mode to measure the 60 s and the measurement11 53 43 11 55 43 11 57 44 11 59 47 12 01 50spectroscopy (CRDS) was employed in the GD mode to measure the 60 s and the measurement 11:53:43 11:55:43 11:57:44 11:59:47 12:01:50H O CO and CH fluxes at a lake atmosphere interface h d t d t t i lTi DOY 227H2O, CO2 and CH4 fluxes at a lake-atmosphere interface. approached steady state in lessTime, DOY 2272 2 4 p approached steady state in less ,
O t d t b th fi t tt t t i th fl than 10 s after each switchingSchematic design diagram of the gradient measurement system Step changes in the CO CH and H O mixing ratios in response to valve switching Our study appears to be the first attempt at measuring these fluxes than 10 s after each switching. Schematic design diagram of the gradient measurement system Step changes in the CO2, CH4 and H2O mixing ratios in response to valve switching Our study appears to be the first attempt at measuring these fluxessimultaneously using one instrument and in a long term uninterruptedsimultaneously using one instrument and in a long-term uninterruptedy g g poperationoperation.ope a o
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gmeasurement system at Lake Taihu from May 11 to August 31, 2012
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their respective source footprintsCH flux was positive most of the time except for occasional their respective source footprints. CH4 flux was positive most of the time except for occasional p pnegative values at nightnegative values at night. g g
Acknowledgement: This research was supported by the Natural Science Foundation of Jiangsu Province China (grant BK2010572) the Ministry of Education of China (grant PCSIRT) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (grant PAPD)Acknowledgement: This research was supported by the Natural Science Foundation of Jiangsu Province, China (grant BK2010572), the Ministry of Education of China (grant PCSIRT) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (grant PAPD).pp y g (g ) y (g ) y g p g g (g )
