Kuliah 8d-Stomatal Conductance

8/3/2019 Kuliah 8d-Stomatal Conductance

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Assessing Amazon regional energy, water andcarbon exchange using SiB3/LIS

NASA/LBA-ECO (CD36)

Rafael Rosolem (University of Arizona)

Luis Gustavo Goncalves de Goncalves (NASA GSFC)

William James Shuttleworth (University of Arizona)

July, 2007


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Who am I?Where do I come from?

Piracicaba, SP, Brazil

BSc in Meteorology (2002) at Univ. of So

Paulo

- Undergrad Research with soilrespiration controlled by soil temperature

and moisture

MSc in Agricultural Systems Ecology (2005) at Univ. of So Paulo- Impact of regional Amazon deforestation on water-energy fluxes caused by

road paving (BR-163 highway)

Visiting Research Collaborator (2003/2004) at UofA- Automatic parameter estimation techniques applied to SiB2 using Amazon

site dataset

PhD candidate at UofA (2006-?)- Energy, water, and carbon exchange over the Amazon basin, LSM,

O timization, Data Assimilation ???


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What are the scientific questions?1. How are the sources and sinks of CO2 located over the Amazon?

2. What is the seasonality of these sources and sinks along the year?

3. Can we identify and quantify the relationships between the carbon

dynamics and energy-water cycles?

Saleska et al. 2003 (Science) Huete et al. 2006 (GRL)


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Why the Amazon rainforest?

STRONG CARBON

DYNAMICS gives us the

opportunity to better identify

and analyze the carbon

exchange over the rainforest

The LBA project has helpedthe scientific community to

better understand the way the

Amazon rainforest function

with respect to the energy,water and carbon exchange

between the biosphere and

atmosphere.


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Why the Amazon rainforest?We have been studying the region for the last couple of years:

- South American LDAS (de Goncalves et al. 2006 - JGR)

-The impact of selective logging on SiB2

parameters using multicriteriaoptimization algorithms (Rosolem et al.

2005 IAHS Assembly)


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Why the Amazon rainforest?

Available eddy flux

measurements for modeling

(calibration/validation)

Source: Dr. Scott Saleska


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Why the Simple Biosphere Model?

SiB type models have been widely used in climate studies worldwide,

including the Amazon region

e.g. Nobre et al. 1991 (J.

Climate) impact of

large-scale Amazon

deforestation on climate

using SiB

e.g. Randal et al. 1996 (J.Climate) SiB2 and

remote sensing data

coupled to CSU GCM

Temp Prec

NEP


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New Features:

- Prognostic T, e, CO2,

other tracers in canopyair space;

- 10-layer soil (T and w),with adjustable water

extraction profile (roots);- Snowpack of 0-5 layers;

- Mixed canopy physiology

(e.g., savanna); and- Stable isotopefractionation of CO2.

UmP

G

S LRn

Cm

(CO2)

EmHm

S L

ra

rb

rd

rsoil

Ci3

Ci4

TcSPAR

Wg

T

T

ec*

eg*

ec*

Cs3

Cs4

rc3

rc4

rc

Iws

Erc

Ewc

EcHc

Ac

A c3

A c4es

Tc

(Vc fcG LT)

EgRg Hg

Hg

Ewg

Rg Esoil

Rroots

Rmicrobes

Wrun

Esoil

Wthru

Wleaf

Wdrain

Wdrip

Canopy

Air Space

Leaf Surface

Ewg

Ewc

Hc

Ac

-

-

-

-

-

-

+

+

h NADPH

ATP

3-PGA

1,3-diPGA

3PGAld

DHAP

F1,6diP

F-6P

R-5-P

RuBP

Ru-5-P

G-6-P

G-1-P

ADPG

Starch

ATP

NADPHATP

CO2(or O2)

fc4

fc3

Z1

Z2

Zm

Erc

eg*

Tg

emTm

rG

Wc

W

W

W

W

Am

(H2O)

Atmosphere

Canopy

Soil

Win

Ta Ca ea

1

2

T...

T...

T10W10

9W

W

W

8

7

W1 ...

...

...

...

...

Soil Temperature and Soil

Water are solved after

Canopy Air Space

Iws

ISOFRAX

Improved version: Simple Biosphere Model v.3 CSU

Adapted from Dr. Denning slides


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Photosynthesis, stomatal function and water

Plants need CO2(photosynthesis)

Open their stomata to absorb

CO2

H2O is then released as a

consequence

For every CO2 molecule

absorbed ~400 molecules of

H2O is released

Adapted from Dr. Denning slides


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Stomatal conductance is linearly related to photosynthesis:Semi-empirical model of leaf conductance gs

(Ball-Berry-Collatz)

Photosynthesis is controlled by three limitations

(The Farquhar-Berry model):

Enzyme-limitedrate (RuBisCO)

Light-limitedrate

Sink-limitedrate

n ss

s

A hg m p b

c= +stomatalconductance

Net CO2

assimilation(photosynthesis)

CO2 at leaf surface

RH at leaf surface

min( , , )n C L S d A A A A R=

Photosynthesis and stomatal conductance (leaf scale)

empirical coefficient(C3 ~ 9, C4 ~ 4)

Atmospheric pressuregs_MIN

(C3 ~ 0.01,C4 ~ 0.04)

Darkrespiration

rate


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Photosynthesis and stomatal conductance (canopy scale)

( )ns Afg =

( ) ( ) =2

12

,,,,0maxz

zCOc dzWTepfPARVfg

( )( )c

p

bc

acct W

c

rg

eTeE

+

= 121

*

From previous slide: (leaf scale)Integrate for the entire canopyCanopy top

Canopy bottom Max RuBisCOcapacity at top

canopy

PhotosyntheticallyActive Radiation

CO2 partialpressure

Water vaporpressure deficit

Temperature

Soil moisture

PAR-useparameter

Photosynthesis-conductance model (e.g. SiB) directly linksthe plant transpiration with net assimilation (An)

Canopytranspiration rate

Saturated vaporpressure at canopyAtmosphere vaporpressure

Canopy stomatalconductance

Canopy stomatalconductance

Plant to CASaerodynamic resistance

Density, specificheat of air

Psychrometric constant

Fractional canopywetted area


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Carbon exchange

Usually neglected interrestrialecosystems(may be important inthe oceans)

(NEE)

(GPP)

(Rautotrophic)

(Rheterotrophic)


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Carbon exchange(NEE)

(GPP)

(Rautotrophic)

(Rheterotrophic)

( )

NEPNEE

RGPPNEP

RRGPPNEP

RNPPNEPRGPPNPP

ysteme

hicheterotropcautotrophi

hicheterotrop

cautotrophi

=

=

+=

= =

cos

Carbon

exchange

(Ecolog

y)

Jan Jul Dec

0

Carb

onexchange

(AtmosphericScience

s)

GPP

Recosystem

Carbonuptake

Carbonrelease

NEP


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Feedback mechanisms and limiting factors

Structural Physiological

positive

negative

Adapted from Pitman 2003 Int J Clim.

Nemani et al. 2003 Science


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Why Sib3/LIS?


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Why Sib3/LIS?

-Integrates different sources of data (e.g., remotesensing, ground-based data) with LSM;

-Improves land surface characterization;

-Applications in agriculture, water resource management,and flood, weather, and climate predictions


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Why Sib3/LIS?

Different sources of forcing data in the Amazon (examples)

South American LDASDe Goncalves et al. 2006 - JGR

Adapted from Dr. Goulden slides

h /


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Why Sib3/LIS?

SiB3

An Rc

RrootRg

NEECarbon

Balance

Ti i i


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Time-varying inputs

New phenology module that reads monthly time-varyinginputs from 1o x 1o map (climatology)

-Absorbed fraction of PAR (aparc)

-Leaf area idex (m2 m-2) (zlt)-Greenness fraction (-) (green)-Roughness length (m) (z0d)

-Zero plane displacement height (m) (zp_disp)-Bulk PBL resistance coefficient (rbc)-Ground to CAS resistance coefficient (rdc)-Time-mean leaf projection (gmudmu)

-Canopy gap fraction for thermal IR radiation (-) (thermk)

Better results than look-up table values associated with

vegetation type!!!

Ti i i t ( l )


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Time-varying inputs (examples)aparc (January) aparc (June)

aparc (June minus January)

Q lit ti l i ( J t M )


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Qualitative analysis (average Jan to May)

CO2 assimilation Plant respiration

Net CO2 assimilation

Q lit ti l i ( ti l t l l i )


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Qualitative analysis (spatial-temporal analysis)

CO2 assimilation Plant respiration

Night (no assim.)

Day Day (photo resp)

Night (maintenance resp)Net CO2 assimilation

Units: mol m-2 s-1 Lat = 3oS

S il pi ti


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Soil respiration

Shows also diurnal variation and heterogeneity

But values are TOO HIGH!!!

Units: mol m-2 s-1 Lat = 3oS

Carbon exchange components (L t 3 S L 54 W)


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Carbon exchange components (Lat = 3oS; Lon = 54oW)Units: mol m-2 s-1

Step 1: CO2 assimilation

Carbon exchange components


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Carbon exchange componentsUnits: mol m-2 s-1

Step 2: Plant respiration



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Up to this point, it is OK.

Units: mol m-2 s-1Step 3: Net CO2 assimilation



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TOO HIGH!!!

Units: mol m-2 s-1Step 4: Soil respiration



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As a consequence, values are unrealistically high

Units: mol m-2 s-1Step 5: Net ecosystem exchange (NEE)

Comparison with EC flux tower (Lat=3oS/Lon=54oW)


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Comparison with EC flux tower (Lat=3oS/Lon=54oW)

Off course, this was expected !!!

Units: mol m-2 s-1

Current modifications


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Current modifications

SiB3

An Rc

RrootRg

NEECarbon

Balance

Phenology moduleaparc, zlt, green, z0d,

zp_disprbc, rdc, gmudmu,

and thermk(Monthly)

In summary


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In summary

SiB3 may benefit from LIS framework in terms of:

- Handling several potential input data to the model(remote sensing data, regional forcing data SALDAS,ground-based data);

- Its ability to perform regional simulation with highresolution components (parameters, time-varying inputs);

- Providing a better estimation of the carbon exchangecomponents (land cover and soil texture heterogeneity);

Challenges


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Challenges

-energy and water balance components (not yet tested);

-Model initialization: soil moisture (couple of years);

carbon (couple of centuries) (e.g., soil respirationresults);

-Model calibration and validation within the domain;

Note: The LBA-MiP may provide useful procedures and

techniques related to above challenges that we may applyto our study (e.g., 10 km x 10 km maps of time-varyinginputs are already available for the region and will beimplemented in the future)

10km x 10km time-varying input maps


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10km x 10km time varying input maps-Derived from 20 year long NASA/NOAA AVHRR Pathfinder NDVI

dataset (using empirical relationships);

10km x 10km Leaf area index (Jan)


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10km x 10km Leaf area index (Jan)

Next steps


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p

-SiB3 offline experiments (run in parallel with SiB3/LISframework);

-10km x 10km time-varying input maps (Dr. Stockli from

Dr. Scott Dennings group) already available;-Spin-up experiments (soil moisture and carbon);

-Discuss the results with Scott Dennings group which

provided the model code (not yet released) and support

(Dr. Ian Baker);

-Survey of remote sensing products that may be usefulfor this study (e.g., MODIS);

-Use EC flux towers for validation and calibration

experiments.

Acknowledgements


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Acknowledgements

-Gustavo and David Toll (visiting NASA/GSFC);

-Dr. Jim Shuttleworth (supervisor);

-Dr. Christa (excellent comments and suggestions);

-Regina Izzo (computer and technical support)

Any comments, suggestions, ideas (PLEASE)

LBA site Bananal


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Rplant

-GPP

LBA site Bananal


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Rground

-NPP

LBA site Bananal


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NEE

Kuliah 8d-Stomatal Conductance

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