IMPROVING REMOTE-SENSING BASED GPP ESTIMATES (MODIS-MOD17) THROUGH by FIg19vk

VIEWS: 9 PAGES: 35

									                           Carbon Fusion International Workshop
                                   Edinburgh, May 2006




      On the use of eddy-covariance and optical remote
          sensing data for biogeochemical modelling
                                 Markus Reichstein, Dario Papale

             Biogeochemical Model-Data-Integration Group, Max-Planck-Institute Jena
                         Laboratory of Forest Ecology, University of Tuscia



   Biogeochemical


       BEAM-DIG

        MPI-BGC




Model-Data Integration
       Group
                  BGC-Model-Data Integration Overview

               Ecosystem models


                    + provide system understanding
                    + promise inter-/extrapolation capacity
                    + may include historical effects
                    – are simplifications of the world
                    – can’t predict stochastic events




Ecosystem data
                                                Remote sensing
   + Potentially high quality
   + often high temporal resolution
                                                  + objective/consistent observations
   – data compatibility ?                         + spatially and temporally dense
   – ‘point’ observations
                                                  – data quality lower
                                                  – processes not directly observable,
                                                            no history, no prediction
 Carbon Fusion Workshop, Edinburgh May 2006                               Markus Reichstein
                                      Outline

 • Introduction to eddy covariance data

 • Bottom-up perspective of an ‘ideal’ data
   integration-validation process

 • Problems and obstacles in this process




Carbon Fusion Workshop, Edinburgh May 2006      Markus Reichstein
    Observing ecosystem gas exchange: eddy
                   covariance
               Flux = speed x concentration




                                                                  Photo: Baldocchi
Carbon Fusion Workshop, Edinburgh May 2006    Markus Reichstein
Eddy covariance

+ Measures whole ecosystem
exchange of CO2 and H2O, …                      CO2,
                                                H2O
+ Non-destructive & continuous
+ time-scale hourly to interannual
+ integrates over large area

- only on flat sites
- relies on turbulent conditions ==>
data gaps, stochastic data
- source area varying (flux footprint)
- only ‚point‘ measurements

Does not deliver compartment fluxes,
but:
NEP = GPP - Reco



   Carbon Fusion Workshop, Edinburgh May 2006     Markus Reichstein
                                            Half-hourly eddy covariance data
      Carbon flux [µmol m-2 s-1]
                                          15
                                          10                 Respiration
                                           5
                                           0
                                          -5
                                         -10
                                         -15
                                         -20                          Carbon uptake
                                         -25
                                         280
                                           5/2001   6/2001   7/2001   8/2001   9/2001 10/2001 10/2001 11/2001 12/2001           1/2002
       Water flux [W m-2]




                                         230                           Evapotransp.
                                         180
                                         130
                                          80
                                          30
                                         -20
      Soil water content [fraction FC]




                                           5/2001
                                         1.20       6/2001   7/2001   8/2001   9/2001   10/2001   10/2001   11/2001   12/2001   1/2002
                                         1.00
                                         0.80
                                         0.60
                                         0.40
                                         0.20
                                         0.00
                                           5/2001   6/2001   7/2001   8/2001   9/2001 10/2001 10/2001 11/2001 12/2001 1/2002


Carbon Fusion Workshop, Edinburgh May 2006                                                                               Markus Reichstein
    Network of ecosystem-level observations



   >1000 site-years  1012 raw measurements (1013 bytes)

   Raw data                                                            Knowledge

             Turb stat.         Synth./aggr.          Model param.
   1013                  108                  106                   102 bytes

    • Network and intercomparison studies
    • Harmonised and documented data processing
         • Aubinet et al. (2000), Falge et al. (2001), Foken et al. (2002),
            Göckede/Rebmann/Foken (2004) : general set-up and methodology, quality
            assurance, gap-filling
         • Reichstein et al. (2005), Glob. Ch. Biol.: u*-correction, gap-filling, partitioning
            of NEE
         • Papale et al. (in prep), Biogeosciences: Quality control, eval. uncertainties
         • Moffat et al. (in prep): Gap-filling inter-comparison
         • Online processing tool: http://gaia.agraria.unitus.it/lab/reichstein/
Carbon Fusion Workshop, Edinburgh May 2006                                      Markus Reichstein
       Ideal model-data integration cycle (bottom-up)

Model application                     Model
                                 (re)formulation
                                 (Definition of model
                                      structure)
                                                                  Model
      Model validation                                        characterization
       (against indep. data,                            (Forward runs, consistency check,
        by scale or quantity)                              sensitivity, uncert. analysis)


                                      DATA
     Generalization                                            Model
         (‘up-scaling’)                                  parameter estimation
                                                             (Multiple constraint)

                                   Parameter
                                 interpretation
                                     (Thinking)

   Carbon Fusion Workshop, Edinburgh May 2006                                 Markus Reichstein
                         The bottom-up model PROXEL
                               Solar radiation   Air temperature   [CO2]   Relative humidity   Wind speed




 LAI, SAI
                                                      {Quantum use efficiency,                                 CO2
                              Canopy Layer 1          electron transport and                                   H2O
                              Canopy Layer 2
 Phenology
                              Canopy Layer 3
                                                      carboxylation capacities,
                                       .
 Leaf
                                       .
                                       .               stomatal conductance}
                              Canopy Layer n
 physiology
                              Canopy
            effective soil                                                Vapour pressure
                                                   Water
                               Precipitation                                                   H2O
                                                 extraction Air temperature Wind speed

 Soil hydraulic
   parameters

   Soil thermal                                                                                                CO2
                              Soil Layer 1
   parameters                 Soil Layer 2
Soil respiration              Soil Layer 3
                                       .
                                       .
                                       .
    parameters
                              Soil Layer n
    Root distri-
         bution               Soil

   Carbon Fusion Workshop, Edinburgh May 2006                                              Markus Reichstein
                                                 I. Model charaterization / forward model run
                                                 Well watered conditions                   Drought stressed conditions




                                                                                                                                       Reichstein, Tenhunen et al., Global Change Biology, 2002
                                          0.2
                                                  (a)                         Eddy cov.     (b)
                                          0.18
                                                                              Sap flow
                                          0.16                                Modelled
         H2O flux [mm/h]                  0.14
                                          0.12
                                          0.1
                                          0.08
                                          0.06
                                          0.04
                                          0.02
                                            0
                                                  (c)                         Eddy cov.     (d)
                                           12                                 Modelled
         CO2 flux of GPP [µmol m-2 s-1]




                                           10
                                            8
                                            6
                                            4
                                            2
                                            0
                                           -2 0         4   8      12    16      20   24    0     4   8     12     16   20   24
                                                            Local time [hr]                           Local time [hr]

Carbon Fusion Workshop, Edinburgh May 2006                                                                         Markus Reichstein
          II. Dual-constraint parameter estimation




Target region




                                                                  Reichstein et al. 2003, JGR
 Carbon Fusion Workshop, Edinburgh May 2006   Markus Reichstein
                        IIa. Inferred parameter timeseries

                        1.8




                                                                    Rain event
                                                                    Rain event
                                                                    Rain event
                                                                    Rain event
                               Estimated course of photosynthetic
                        1.6    capacity (Vcmax)
                        1.4
    Relative capacity




                        1.2

                         1

                        0.8

                        0.6

                        0.4

                        0.2

                         0
                             150                200                  250              300
                                                  Julian day

Carbon Fusion Workshop, Edinburgh May 2006                                       Markus Reichstein
        III. Interpretation & Generalization

                                     1.4

                                     1.2
            Relative leaf activity

                                      1
                   Relative value



                                     0.8

                                     0.6

                                     0.4

                                     0.2

                                      0
                                           0   0.2     0.4     0.6     0.8    1         1.2
                                                  Relative soil water content
                                                                                  Reichstein et al. 2003, JGR

Carbon Fusion Workshop, Edinburgh May 2006                                              Markus Reichstein
                                                                                     1.8

                                                                                     1.6

 III. Interpretation                                                                 1.4

 and Generalization:




                                                                RUE [gC / MJ APAR]
                                                                                     1.2


 Keyp. RUEmax                                                                          1

                                                                                     0.8

                                                                                     0.6



• inter-PFT variability
                                                                                     0.4

                                                                                     0.2

• intra-PFT variability                                                                0

• f(species, N, T???)                                                                            ENF              EBF               DBF
                                                                                                                                   PFTs color coded
                                                                                                                                   PFTs color coded
                                                                                                                                                      MF                 Sav           Oshrub           Crop




                                                                                                                                                              He6/2                           He6/2
                                                                                                                                                                               He7/2
                                                                                                                                                Ha7/1
                                                                                                                                                     He7/2
                                                                                                                                                        He7/1
                                                                                                                                                         He6/1                 Ha7/1 He7/1
                                                                                                                                                                                      He6/1
                         2000.00
                                2000.0
                                1750.0                                                                                                      Ha6/1
                                                                                                                                             No5/1         No5/1          Ha6/1
                                1500.0                          10                                                         Jo7/1                       Jo7/1              He8/2
                                1250.0
                                                                10                                                                  Ha8/1        He8/2 He5/1
                                                                                                                                                He8/1 He5/2 Ha8/1        He8/1     He5/1
                                                                                                                                                                                  He5/2

                                1000.0                                                                               No6/1    No6/1                      Br6/1
                                                                                                                                                         Br6/1
                                750.0                                                                                                              Th6/1
                                                                                                                                                    TC6/2
                                                                                                                                                      TC6/2      Th6/1
                                         GPP [gC m -2 day- ]]
                                                          1
                                                         -1




                                500.0                                                                             Jo7/2                 Jo7/2         Th7/1         Th7/1
                                         GPP [gC m day


                                                                                                                                                       Br7/1
                                                                                                                                                       Br7/1
                                250.0                                                                                                     No7/1         No7/1 Pi5/2
                                                                                                                                            He9/2
                                                                                                                                             Pi5/2        TC6/1 He9/2
                                                                                                                                                           TC6/1
                                                                                                                                He9/1           He9/1
                                                  -2




                         0.00                                                                                                    Vi6/1 Pu6/1
                                                                                                            El5/1               Vi6/1 Pi6/2             Pi6/2 Sa7/1 Th5/1
                                                                                                                                                        Th5/1 Sa7/1
                                                                                                                                                     TC7/1Pu6/1
                                                                                                                                                       TC7/1
                                                                                                                                                         Vi7/1
                                                                                                                El5/1                     Th8/1       Th8/1 Vi7/1
                                                                                                                                       Pi4/2             Pi4/2
                                                                                                                                                            El7/2
                                                                                                                                                    Hy7/1 Hy7/1
                                                                                                                                                         Br5/1
                                                                                                                                                         Br5/1            El7/2
                                                                                                                                      Sa4/1
                                                                                                                                      Mi4/2 Br8/1 Vi8/1
                                                                                                                                       Sa4/1
                                                                                                                                           Pi7/2
                                                                                                                                          TC5/1        Ha5/1
                                                                                                                                                           Mi4/2                    Ha5/1
                                                                                                                 Ha9/1        Pi7/2
                                                                                                                                Ha9/1
                                                                                                                             Pi9/2        Pi9/2
                                                                                                                                           TC5/1 TC8/1 Vi8/1
                                                                                                                                              Pu5/1
                                                                                                                                               Br8/1              Pu5/1
                                                                                                                               Sa6/1
                                                                                                                                Sa6/1               TC8/1
                                                                                                                           Sa5/1 El6/2 Pu4/1
                                                                                                                          Sa5/1 Bi7/1
                                                                                                                        No8/1          Bi7/1 El6/2
                                                                                                                                      El6/1
                                                                                                                                     No8/1 Hy8/1
                                                                                                                                        Hy8/1 El6/1               Pu4/1
                                                                 5
                                                                 5                                  El4/1
                                                                                                      El4/1                Mi4/1
                                                                                                                           Pi8/2
                                                                                                                       Th9/1 Th9/1 He10/1 Hy6/1
                                                                                                                          Sa10/1
                                                                                                                           Pu3/1
                                                                                                                           Sa10/1
                                                                                                                                      Br4/1 El8/1 El8/2 Sa8/1
                                                                                                                                        Pi8/2
                                                                                                                                         Mi4/1
                                                                                                                                      Br4/1
                                                                                                                                         Hy6/1 Bi5/1
                                                                                                                                        Pu3/1
                                                                                                                                      Jo8/2
                                                                                                                                           Bi5/1             Sa8/1
                                                                                                                                                             El8/1 El8/2
                                                                                                                Th4/1 Th4/1
                                                                                                                  Jo8/2 He10/1
                                                                                                           Ya3/1       Jo6/2 Pu7/1
                                                                                                                 Ya3/1Bi7/1              Sa9/1 Jo6/2
                                                                                                                                             Pu7/1
                                                                                                                                           Sa9/1
                                                                                                                       Bi6/1
                                                                                                                     Th10/1Th10/1
                                                                                                                          Bi7/1
                                                                                                                          Bi6/1
                                                                                                          El3/1 Bi8/2 Bi7/2Bi6/2
                                                                                                                   Jo8/1
                                                                                                                    Bi8/2
                                                                                                                      Br3/1             Jo8/1 TC8/2
                                                                                                        Jo5/2El3/1 Vi9/1 Ya4/2 Bi6/2
                                                                                                                     Jo5/2 Bi7/2
                                                                                                                      Br3/1
                                                                                                                 Ya4/2 Hy5/1
                                                                                                                     Vi9/1 No9/1 No9/1 Jo6/1
                                                                                                                     Jo6/1 Hy5/1
                                                                                                                                                TC8/2
                                                                                                                   Pu10/1 TC9/1
                                                                                                              Sa3/1 Mi2/2 Pu10/1
                                                                                                               Sa3/1 Bi8/1
                                                                                                             Mi2/2 Bi8/1 TC9/1
                                                                                                          Ya2/1Pu2/1 Bi8/1
                                                                                                               Ya2/1 Pu2/1
                                                                                                                          Bi8/1
                                                                                                              Bi9/2 Bi5/1
                                                                                                           Pu11/1Bi5/1
                                                                                                                 Bi9/2
                                                                                                                 Pu11/1
                                                                                                          El2/1 Jo9/2
                                                                                                              El2/1Vi4/1 Ya2/2
                                                                                                                  Ya2/2 Pu8/1
                                                                                                     Jo9/2Br2/1 Ya3/2 Ha10/1
                                                                                                            Hy9/1 Vi4/1 Ya3/2
                                                                                                            Ha10/1
                                                                                                                TC4/1 He10/2
                                                                                                       Mi6/1 Hy9/1Vi10/1 No3/1 Pu8/1
                                                                                                   Mi6/1 Br2/1TC4/1 Br10/1
                                                                                                        Ya1/1 He10/2 Br10/1
                                                                                                            Ya1/1 Vi10/1                No3/1
                                                                                                                                        Br9/1
                                                                                                                                        Br9/1
                                                                                                            Bi10/1
                                                                                                             Bi10/1
                                                                                                              El10/2               Pu9/1
                                                                                                       Br11/1 TC9/2                                Pu9/1
                                                                                              El12/1El1/2 El11/2 El10/2
                                                                                                 Sa12/1
                                                                                                   El1/2
                                                                                                    Mi1/1        Bi9/1
                                                                                                 Sa12/1Mi1/1 TC9/2
                                                                                               El12/1Br11/1
                                                                                                  El12/2
                                                                                                       El11/2
                                                                                                   El12/2
                                                                                                                    Bi9/1
                                                                                                TC10/1 Ya1/2Mi11/1 No10/1No10/1
                                                                                               TC10/1 Mi11/1 Ya5/2 Ya5/2
                                                                                                  Bi10/2 Bi4/1 No2/1
                                                                                                            No2/1
                                                                                                  Bi10/2 Bi4/1
                                                                                                     Vi3/1
                                                                                                   Pu1/1 Ya1/2
                                                                                                    Vi3/1                       He4/2           He4/2
                                                                                                     Pu1/1
                                                                                                  Pu12/1
                                                                                                   Th3/1
                                                                                             Th11/1 Pu12/1 Bi3/1
                                                                                               Th11/1
                                                                                                Th3/1
                                                                                              Vi11/1Br1/1 Bi3/1 Mi7/2
                                                                                                 Br12/1
                                                                                                Hy4/1
                                                                                                 Vi2/1                               Mi7/2
                                                                                        TC10/2Vi2/1 Ya12/2
                                                                                                 Br12/1
                                                                                                Hy4/1
                                                                                         TC10/2 Ya6/1
                                                                                              Vi11/1Br1/1 Ya12/2
                                                                                                     Ya6/1 Jo9/1
                                                                                                              Mi9/2 Mi9/2
                                                                                                               Ha4/1        Ha4/1
                                                                                             Hy10/1
                                                                                             Hy10/1Jo9/1                            He4/1
                                                                                              Th2/1Ya10/1
                                                                                       Vi12/1Bi11/1Ya8/1
                                                                                                 Th2/1
                                                                                        TC11/1Bi2/1 Ya10/1 TC4/2
                                                                                      Vi12/1 Bi11/1 Ya9/1
                                                                                                    Ya9/1
                                                                                            Vi1/1 TC3/2
                                                                                                    Ya8/1
                                                                                       TC11/1Bi1/1 Ya8/2
                                                                                                                       He4/1
                                                                                                                    TC4/2
                                                                                           Vi1/1Bi2/1
                                                                                          Jo10/2 TC3/2
                                                                                                Bi1/1
                                                                                            Bi12/1 Jo4/2
                                                                                         Jo10/1 Ya7/2 He3/2 Jo5/1
                                                                                           Bi12/1 He11/1
                                                                                       Jo10/2 Ya7/2 He2/2
                                                                                             Jo10/1 He11/2          He3/2
                                                                                              Jo4/2
                                                                                     Th12/1 He11/1Jo5/1
                                                                                            Th1/1
                                                                                       Th12/1 He11/2 Ya8/2
                                                                                         TC2/2 He2/2 He3/1
                                                                                      TC11/2 Ha11/1No11/1
                                                                                          Th1/1 No11/1
                                                                                          TC2/2
                                                                                     TC11/2 Ha3/1He3/1
                                                                                       Hy11/1 No12/1Ya9/2
                                                                                                      Ya9/2
                                                                                     Hy11/1 Ha2/1 He2/1
                                                                                             He1/2 Jo4/1
                                                                                         TC3/1 He2/1
                                                                                              No12/1
                                                                                      Ha1/1He12/2
                                                                                          He1/2
                                                                                        TC3/1
                                                                                       Ha1/1
                                                                                       TC1/1
                                                                                      TC1/1He1/1
                                                                                           Jo3/2
                                                                                      Jo11/1
                                                                                        TC1/2
                                                                                         Ha12/1
                                                                                          He12/2
                                                                                      Jo11/2
                                                                                      TC12/1
                                                                                          He1/1
                                                                                       Hy1/1
                                                                                        Jo3/1
                                                                                      Jo12/1
                                                                                      Jo12/2
                                                                                       Jo2/1
                                                                                       Jo1/2
                                                                                       Jo2/2
                                                                                       Jo1/1
                                                                                     Jo11/1
                                                                                      TC1/2
                                                                                      TC12/2
                                                                                     TC12/1
                                                                                     Jo11/2 Ha3/1
                                                                                            Ha11/1
                                                                                       Ha12/1
                                                                                      Hy1/1 Jo4/1
                                                                                        Jo3/2He12/1
                                                                 0
                                                                 0                     Hy3/1
                                                                                      Jo2/1
                                                                                     Jo12/2
                                                                                      Jo2/2
                                                                                      Jo1/1
                                                                                      Jo3/1
                                                                                      Jo1/2
                                                                                     Jo12/1
                                                                                          He12/1
                                                                                     TC12/2
                                                                                       TC2/1
                                                                                      Hy3/1
                                                                                      TC2/1 Ha2/1



                                                                                       0
                                                                                       0                                   55                    10
                                                                                                                                                 10
   Carbon Fusion Workshop, Edinburgh May 2006                                                                                            -2
                                                                                                                                             Markus
                                                                                                                                             -2 -1
                                                                                                                                              -1
                                                                                                                                                                                                      Reichstein
                                                                                                                      GPP_MOD17_MET [gC [gC m d
                                                                                                                     GPP_MOD17epsmax_newm day ] ]
IV. Validation at
                                          29,2° W                                 58° E
                                      70°N

  larger scale
 NEE integrated 12:30-14:30


                              20
                                      60°N

                              15
        [µmol m-2 s-1]




                                             "Les Landes"
                              10
                                      50°N
                               5


                               0

                                   Flight               'Upscaled'   Schmittgen et
                                      40°N                           al. (2004), JGR



                                            11° W                                 23° E
                                                      GCB, in press
Carbon Fusion Workshop, Edinburgh May 2006   Markus Reichstein
                               The problems




Carbon Fusion Workshop, Edinburgh May 2006    Markus Reichstein
To consider with DA of eddy covariance data:

 • How is the error structure of the data
   itself?
 • How to address mismatch of scales
   (‘point’ versus pixel)?
      – Remote sensing
      – Meteorological data
 • How do perform up-scaling from tower
   sites?
      – Representativity
      – Generalization

Carbon Fusion Workshop, Edinburgh May 2006   Markus Reichstein
                          Errors in the data




Carbon Fusion Workshop, Edinburgh May 2006     Markus Reichstein
Error model influence on parameter estimates


                                                    Search strategy
     Parameter estimate



                                                            I
                                                            II




                          Const. abs errors   Const. rel. errors

                                              Simplified after Trudinger et al. (OPTIC)

Carbon Fusion Workshop, Edinburgh May 2006                          Markus Reichstein
              Errors in eddy covariance data

 • Random errors
      – ~ 30% for the half-hourly flux, (turbulences !)
 • Systematic errors
      – can be largely controlled/avoided
 • Selective systematic errors
      – Conditions where the theory does not apply:
      – Low turbulent conditions (night-time)
      – Advection
      → good quality control necessary
 → “Better few unbiased data, than a lot of biased
   data”
 → Uncertainties: mean NEE > interannual variability
Carbon Fusion Workshop, Edinburgh May 2006                Markus Reichstein
       Characterization of the random error



        FLUX t   f Mt , St   
        For small t and similar M(t) :
        St   St  t   FLUX (t  t )  FLUX t   




                                                cf. Richardson et al. (2006)



Carbon Fusion Workshop, Edinburgh May 2006                Markus Reichstein
              NEE                             NEE_sigma

Dec                            Dec                                Quantifying
Nov                             Nov                              uncertainties
Oct                             Oct

Sep                            Sep

Aug                             Aug

Jul                             Jul

Jun                             Jun                                NEE             NEE_sigma
                                                                [µmol m-2 s-1]    [µmol m-2 s-1]
May                            May                                   20.0
                                                                            20         15.00
                                                                            15                 14
Apr                             Apr                                         10                 12
                                                                                               10
                                                                            5                  8
Mar                             Mar                                         0                  6
                                                                            -5                 4
Feb                             Feb                                         -10                2
                                                                    -13.0              0.00
Jan                             Jan
      0   6   12    18    24          0   6      12   18   24


Carbon Fusion Workshop, Edinburgh May 2006                                   Markus Reichstein
  Error distribution of eddy covariance data

                                                                                 3133
                                                                                                       Skewness Kurtosis
                                                                                            Gaussian:       0        0
              0.40                                                                           Laplace:       0        6
                                                                                            Empirical:    -0.08     15




              0.30




                                                                              1401
              0.20                                                                   1286




              0.10

                                                                                        371
                                                                        329

                                                                                              168
                                                                  115
                                                             75                                     66 44 39
                        1   0   3   6   3   11 10 20 31 39                                                   20 15 9   5   5   1    1   0
              0.00
                     -20.0 -16.9 -13.8 -10.8 -7.7 -4.6 -1.5 1.5                               4.6      7.7 10.8 13.8 16.9 20.0
                                                             Error NEE [umol m-2 s-1]


Carbon Fusion Workshop, Edinburgh May 2006                                                                                         Markus Reichstein
      Distribution of model error against eddy data




                                             Chevalier et al. (in rev.)

Carbon Fusion Workshop, Edinburgh May 2006                    Markus Reichstein
                   PDF only 10am-3pm and Jun-Sep


 0.15



                                                                                   42




                                                                                        38   38



                                                                                                       35
 0.10                                                                                             34




                                                                              29

                                                                                                            27




                                                                    17   17
 0.05                                                                                                            16

                                                               14                                                     14




                                                   7   7
                                                           6
                                                                                                                           5
                                                                                                                                   4
                                                                                                                               3
                                               2                                                                                       2
           1                       1                                                                                                                                                1
               0   0   0   0   0       0   0                                                                                               0   0   0   0   0    0   0   0   0   0
 0.00
        -13.9 -12.5 -11.1 -9.7 -8.2 -6.8 -5.4 -4.0 -2.6 -1.2 0.2                                       1.6       3.1       4.5     5.9     7.3     8.7 10.1 11.5 12.9 14.4
                                                                                    NEE error
                                                                                   NEE error
                                                                                    Variable




Carbon Fusion Workshop, Edinburgh May 2006                                                                                                                     Markus Reichstein
          More complicated error structures




Carbon Fusion Workshop, Edinburgh May 2006   Markus Reichstein
                   Maximizing the likelihood?



           Bayesian approach
           Cost function:
               1  f xi , p   OBSi  1
             J 
                       N
                                        
                                             2     P          ˆ j 2
                                                       p j  p
               2 i 1       obs,i
                              2
                                        2 j 1             P, j
                                                            2




                           Trust in data         Trust in apriori
                                                 model parameters



Carbon Fusion Workshop, Edinburgh May 2006                         Markus Reichstein
            Spatial representation problem I

 • Does the tower site represent the
   grid cell of interest?
      – 0.25-2km km for MODIS/SEAWIFS remote
        sensing

      – 30-100 km for meteorological fields

      – 30-100 km for DGVMs, BGCs applied in
        global context

Carbon Fusion Workshop, Edinburgh May 2006    Markus Reichstein
               Spatial heterogeneity...


Aerial photo


                                          1 km
Landsat



MODIS
                         It‘s not always so bad...




TM 3,4,7                                       MODIS 1,2,7

    TM3 coeff. of
       variation




                                                     Dinh et al., subm.

  Carbon Fusion Workshop, Edinburgh May 2006           Markus Reichstein
           Spatial representation problem II

 • Does the network of tower sites
   represent the spatial domain of
   interest or are there chances to
   generalize with scaling variables?




Carbon Fusion Workshop, Edinburgh May 2006   Markus Reichstein
  fAPAR [MODIS-RT)




                      We have to have up-scaling strategies


                                        Day of the year


Carbon Fusion Workshop, Edinburgh May 2006                 Markus Reichstein
                                  Conclusions

 • Eddy covariance data contains a lot of
   interpretable information on both carbon and
   water cycle
 • Inclusion of pools and fluxes for system
   understanding and for linking short and long
   time-scales necessary
 • Major challenge within eddy data
      –   Characterization of the error (random, bias)
      –   Scale and representativeness problem
      –   Interpret. & Generalization of site specific parameters
      –   Documentation of site dynamics, that may violate model structure
          (e.g., soil water, management)

Carbon Fusion Workshop, Edinburgh May 2006                     Markus Reichstein
                                  Conclusions




Carbon Fusion Workshop, Edinburgh May 2006      Markus Reichstein

								
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