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University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
CLASSIC –AMMA
Fieldwork 2005/2006 and modelling activities
Jon Bennie, Claire Damesin, Josiane Seghieri and Lina Mercado
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Outline
• Motivation and objectives• About the JULES model• CLASSIC –CESBIO measurements What have we learned from measurements Model evaluation using physiological measurements• 2006 Fieldwork campaign
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Aim:
To collect physiological and environmental data to improve the performance of land-surface models, particularly JULES (The Joint UK land atmosphere simulator) in arid environments.
Evaluate the sensitivity of plant physiological processes to temporal and spatial variations in climate.
Sensitivity analysis – what parameters are most important in constraining fluxes in the land surface scheme?
Objectives:
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Campaign (2005/2006)
objectives:
Characterise diurnal cycle and spatial variability of surface temperatures (soil and plants) and soil moisture.
Characterise diurnal cycle of Photosynthesis and stomatal conductance – interspecies comparison under the same conditions.
Changes in leaf area index and plant fractional coverduring the measuring period.
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
What did we measure?
Diurnal cycles of:
Photosynthesis and transpiration (IRGA)
Stomatal conductance (porometer, IRGA)
Leaf water potential
(pressure chamber)
Characterisation of species leaf-level response to light and temperature (IRGA).
Leaf level measurements
on herbaceous and
woody plants
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
What did we measure?Soil and leaf temperatures :
Tsoil :bare soil, soil under vegetation
Tvegetation: sun/shade leaf
herbaceous woody plants
Tstems
Soil moisture
-Sampled within the flux tower footprint
- Within a 1km transect
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Continuous surface and sub-surface temperatures and soil moisture
What did we measure?
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
What did we measure?LAI , fractional cover and vegetation classifications (CESBIO protocols)
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
The sun TeamZornia gloghidiata (C3)
Cenchrus biflorus (C4)
Alysicarpus ovalifolus (C3)
0
100
200
300
400
500
600
05:16 07:40 10:04 12:28 14:52 17:16 19:40
Time
gs
(mm
ol
m-2
s-1
)
0.40.50.60.70.80.91.01.1
5:16 7:40 10:04 12:28 14:52 17:16 19:40
LW
P (
MP
a)
Zornia gloghidiata (C3)
Cenchrus Biflorus (C4)
Dactiroctenium (C4)
0
100
200
300
400
500
600
05:16:48 07:40:48 10:04:48 12:28:48 14:52:48 17:16:48 19:40:48
Time
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
05:16 07:40 10:04 12:28 14:52 17:16 19:40
14.08.05 18.08.05
What have we learned ?
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Comparison of Gs and LWP among C3 and C4 species
12/08/05
13/08/05
15/08/05
0
100
200
300
400
500
600
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00
Gs [
mm
ol m
-2 s
-1]
0
0.5
1
1.5
2
2.5
3
Tragus (C4) Alysicarpus (c3) Cenchrus (C4) zornia (C3) Dactiroctenium (C4) Balanites C3 Cmbreton_joung C3 Cmbreton_old C3
LW
P [
Mp
a]
Tragus Alysicarpus Cenchrus Zornia Dact. Balanites Comb. Y Comb. A
C3 C3 C3
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
The ‘shade’ Team
-10
0
10
20
30
40
50
60
00:00 06:00 12:00 18:00 00:00
time
A (
μm
ol m
-2 s
-1 )
Alysicarpus
Cenchrus
Zornia
0
5
10
15
20
25
30
00:00 06:00 12:00 18:00 00:00
time
Tra
nsp
irat
ion
( m
mo
l m-2 s
-1 )
Alysicarpus
Cenchrus
Zornia
-4
-2
0
2
4
6
8
10
12
14
00:00 06:00 12:00 18:00 00:00
time
Wate
r u
se e
ffic
ien
cy
( μ
mo
l C
O 2 m
mo
l-1 H
2O
)
Alysicarpus
Cenchrus
Zornia
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Transect sampling of surface temperature
herbs
bare soil
11th Aug. 05
Sampling along 1 km transects within the footprint of the flux tower
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
JULES
The Joint UK Land Environment Simulator (JULES), based on MOSES, the original land surface scheme of the Hadley Centre GCM.
JULES is being developed with regular “official” releases (currently JULES v.1.0) and a modular structure.
The flexible structure is intended to allow it to be modified and developed by the community to suit different requirements, spatial scales (from flux-tower to global models) and complexity.
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Assessing JULES
-10
0
10
20
30
40
50
60
00:00 06:00 12:00 18:00 00:00
time
A (
μm
ol m
-2 s
-1 )
Cenchrus
C4 modelled
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
00:00 06:00 12:00 18:00 00:00
time
Sto
mat
al c
on
du
ctan
ce (
mo
l m-2 s
-1 ) Cenchrus
C4 modelled
-5
0
5
10
15
20
25
30
35
00:00 06:00 12:00 18:00 00:00
time
A (
μm
ol m
-2 s
-1 )
Zornia
C3 modelled
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
00:00 06:00 12:00 18:00 00:00
time
Sto
mat
al c
on
du
ctan
ce (
mo
l m-2 s
-1 )
C3 Modelled
Zornia
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
JULES runs using Agoufou met data.
August 14th 2005.
Surface conductance Gross primary productivity
Evapotranspiration
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Preliminary analysis suggests:
-Current JULES parameterisation of the Farquhar model of photosynthesis for C3 plants leads to much lower gs than observed in leaf-level field measurements.
-We expect an underestimation of water fluxes from the landscape even when C3 plants are not the dominant functional type.
-e.g. If the ratio of C3/C4 cover is 0.35, mean daily error for July-August 2005 water flux would be 25%.
-Full sensitivity analysis of JULES to soil and plant physiological parameters at the site is planned.
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Fieldwork campaign 2006
Continue measurements initiated in 2005
Further diurnal cycles of physiological variables stomatal conductance and photosynthesis
Complete data-set of leaf-level responses for dominant woody and herbaceous species at the site – temperature, PAR, CO2, soil moisture.
Continuous surface measurements (IRT) and (transects within tower flux print and 1km) Soil moisture Plant and soil temperature
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Fieldwork campaign 2006
Possible new measurements in 2006 (to discuss)
Within the flux foot print
Leaf optical properties Measurements of reflectance and transmittance to infer leaf absorptance (possible use of Field
spectroradiometer)
Soil properties Bulk density/porosity; soil moisture release data
Heat conductivity and heat capacity Water potential/water content curve
University of Wales Swansea CEH Wallingford CEH Monks Wood University of Durham MetOffice
Aknowledgements
Valerie Le Dantec, Eric Mougin,Frank Timouk,
Francois Lavenu, Francoise Guichard, Laurent Kergoat, Colin
Lloyd, Chris Taylor, Caroline Bain, Caroline Houldcroft,Frederic
Baup, Alexi Berg, Richard Dupont,Amusthapha Traore,
Amusthapha , Yacuba,Taraweti