fluxnet 2009 progress dennis baldocchi, rodrigo vargas, youngryel ryu, markus reichstein, dario...
TRANSCRIPT
Fluxnet 2009 Progress
Dennis Baldocchi, Rodrigo Vargas, Youngryel Ryu, Markus Reichstein, Dario
Papale, Deb Agarwal, Catharine Van Ingen
AmeriFlux 2009
FLUXNET: From Sea to Shining Sea500+ Sites, circa 2009
Global distribution of Flux Towers Covers Climate Space Well
Can we Integrate Fluxes across Climate Space, Rather than Cartesian Space?
FLUXNET Community Outreach
• NewsLetter, FluxLetter• Asilomar Workshop• Distributed Searchable Database,
www.fluxdata.org• Fluxnet Visitors
– Paul Stoy, Sebastiaan Luysaaert, Josep Penuelas, Bart Kruijt
Fluxnet Modeling and Data Workshop Asilomar Conference
Questions/Topics: What is the FLUXNET Measurement Community providing to the Modeling Community?What information and data products do modelers need from the FLUXNET measurement community?How can sensitivity runs from land surface models help us interpret flux data across climate gradients and plant functional types?Future composition of FLUXNET
Data Archive, Synthesis, Searchable and Manipulative Databasewww.fluxdata.org
Progress on the ‘LaThuile’ Synthesis Papers
Water Use Efficiency, Coupling Water and Carbon Fluxes
Beer et al. 2009. Global Biogeochemical Cycles
Scales of Flux Variance
Paul Stoy et al, Biogeosciences, Submitted
Vargas et al. New Phytologist, in press
Role of Mycorrhyzae and C Fluxes
Results and Discussion
Emerging Ideas, Science Beyond Routine Flux Measurements
• Continental/Global Upscaling in Time/Space• Flux Spectra across scales of Hours to Decade• PhotoDegradation• Site MetaData Syntheses
– Leaf clumping, albedo• Model Data Assimilation
Towards Continental and Global Representativeness
The Network is not like Acupuncture (credit M Reichstein). Fluxes from Towers represent far beyond their geographical domain.
But we are not Everywhere, All the Time, so We must rely on partnerships with Remote Sensing and Meteorological Data to Upscale
Spatial Variations in C Fluxes
Xiao et al. 2008, AgForMet
springsummer
autumn winter
Using Flux Data to produce Global ET maps, V1
No data
0 - 150
150 - 300
300 - 450
450 - 600
600 - 750
750 - 900
900 - 1,236
ET (mm H2O y-1)
180°
180°
135° E
135° E
90° E
90° E
45° E
45° E
0°
0°
45° W
45° W
90° W
90° W
135° W
135° W
180°
180°
60° N 60° N
30° N 30° N
0° 0°
30° S 30° S
60° S 60° S
Fig.9 Global Evapotranspiration (ET) driven by interpolated MERRA meteorological data and 0.5º×0.6º MODIS data averaged from 2000 to 2003.
Wenping Yuan
Martin Jung
Using Flux data to produce Global ET maps, v2
How many Towers are needed to estimate mean NEE,And assess Interannual Variability, at the Global Scale?
We Need about 75 towers to produce robust Statistics
How Big Does the Network Need to Be?
Over-Arching Questions relating to Statistical Representativeness
• As the sparse Network has grown, can it provide a Statistically-Representative sample of NEE, GPP and Reco to infer Global Behavior?, e.g. Polls sample only a small fraction of the population to generate political opinion
• Can Processes derived from a Sparse-Network be Upscaled with Remote Sensing and Climate Maps?; e.g. We don’t need to be everywhere all the time; We can use Bayes Theorem and climate records to upscale.
• If mean Solar inputs and Climate conditions are invariant, on an annual and a global-basis,are NEE, GPP and Reco constant, too?; e.g. global GPP scales with solar radiation which is constant
Apply Bayes Theorem to FLUXNET?
(climate | ) ( )( | climate)
(climate)
p flux p fluxp Flux
p
Estimate Global flux by Integrating p(Flux|climate) across Globally-gridded Climate space
p(flux) from FLUXNETp(climate|flux) prior from FLUXNETp(climate) from climate database
Probability Distribution of Published NEE Measurements, Integrated Annually
FLUXNET Database
NEE (gC m-2 y-1)
-1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600
pd
f
0.00
0.02
0.04
0.06
0.08
0.10
mean= -225 +/- 227 gC m-2 y-1
n=254
Global GPP = 1033 * 110 1012 m2 = 113.6 PgC/y
Probability Distribution of Published GPP Measurements, Integrated Annually
FLUXNET Database
GPP (gC m-2 y-1)
0 1000 2000 3000 4000
pd
f
0.00
0.01
0.02
0.03
0.04
0.05
mean= 1033+/- 631 gC m-2 y-1
n=253
0
500
1000
1500
2000
2500
3000
12
34
56
78
-10-5
05
1015
20
GP
P (
gC m
-2 y
-1)
Rg
(GJ
m-2 y
-1 )
Tair (C)
FLUXNET Database
0 500 1000 1500 2000 2500 3000
Joint pdf GPP, Solar Radiation and Temperature
E[GPP]= 1237 gC m-2 y-1~136 PgC/y
What Happens to the Grass?
OctoberJune
Vaira Ranch, 2007
200 400 600 800 1000-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Rglobal
W m-2
FC
O2
mol
e m
-2 s
-1
2007
soil CO2 flux-gradienteddy covariance
PhotoDegradation
Baldocchi, Ma, Rutledge
Remote Sensing of Canopy Structure and GPP
Remote Sensing and Ecosystem Metabolism
VI vs GPP when including all data.LED spectral region (white box) looks showing good correlation, but the high correlation region is large.
White rectangle box indicates LED spectral region
Williams et al. 2009. Biogeosciences
Incorporating Soil Evaporation Scheme in CABLE Improves Model Performance
Vargas et al New Phytologist, in press
Priestley-Taylor and Surface Conductance
Chris Williams
Testing Budyko
Chris Williams: EcoHydrology
Beer et al. 2009. Global Biogeochemical Cycles
And, WUE scales with LAI and Soil Moisture
Plant functional types
CRO DBF EBF ENF GRA MF OSH WSA
Clu
mp
ing
in
de
x
0.5
0.6
0.7
0.8
0.9
1.0
LAI-2000 (apparent clumping index)Literature (element clumping index)
2/
0
2/
0
sincos])(ln[2
sincos])([ln2
dP
dP
o
o
app
Apparent clumping index can constrain true clumping index
Ryu, Nilson, Kobayashi, Sonnentag, Baldocchi (to be submitted)
Hollinger et al 2009 Global Change Biology
Albedo and Nutrition
Annual Integrated Kin Departure (MJ m2)-15 -10 -5 0 5 10 15
ARM_SGP_MainBondville
Bondville_Companion_SiteFermi_Agricultural
Mead_IrrigatedMead_Irrigated_Rotation
Mead_RainfedWalnut_River
Chestnut_Ridge Duke_Forest_Hardwoods
Missouri_Ozark Morgan_Monroe_State_Forest
UMBS Walker_Branch
Willow_CreekBlack_Hills
Duke_Forest_Loblolly_Pine Flagstaff_Managed_Forest
Flagstaff_Unmanaged_Forest Niwot_Ridge
UCI_1850 UCI_1930 UCI_1964
UCI_1964wet UCI_1989 UCI_1998
Wind_River_Crane_SiteAudubon_Grasslands
Brookings Canaan_Valley
Duke_Forest_Open_Field Fort_Peck
Kendall_GrasslandIvotuk
Flagstaff_Wildfire Freeman_Ranch_Mesquite_Juniper
Santa_Rita_Mesquite_Savanna UCI_1981Vaira_Ranch
Lost_CreekFermi_Prairie
Heat absorbed Heat reflected
Croplands
Deciduous
Evergreen
Grasslands
Savannas
Integrated annual error, or departure in the shortwave energy budget, for each site as derived from the calculated biome mean albedo.
Albedo and Climate Forcing
Tom O’Hallaran
mean annual Tsoil, C
-20 -10 0 10 20 30 40
mea
n an
nual
Tai
r, C
-20
-10
0
10
20
30
40
Coefficients:b[0] -0.468b[1] 0.957r ² 0.884
FLUXNET Database
Optimizing Seasonality of Vcmax improves Prediction of Fluxes
Wang et al, 2007 GCB