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CANOPY TEMPERATURE FOR SIMULATION OF
HEAT STRESS IN IRRIGATED WHEAT A MULTI-MODEL COMPARISON
Heidi Webber - Pierre Martre - Senthold Asseng - Bruce Kimball - Jeffrey White - Michael Ottman - Gerard W. Wall - Giacomo De Sanctis - Jordi Doltra - Robert
Grant - Belay Kassie - Andrea Maiorano - Jørgen E. Olesen - Dominique Ripoche - Ehsan Eyshi Rezaei - Mikhail A. Semenov - Pierre Stratonovitch - Frank Ewert
1
2
0
15
30
45
0 500 1000 1500 2000 2500 3000
Stress thermal time (oC min, >31
oC)
Gra
in n
um
be
r p
er
ear
Roda Christgrün Nossen
Roda Christgrün Nossen
STT20
STT200
(Siebert, Ewert, Eyshi Rezaei et al., 2014)
rainfed
irrigated
• Heat stress to increase with
climate change
• How to account for in crop
models?
sand
loam
𝛾∗ = 𝛾 1 +𝑟𝑐
𝑟𝑎
𝑇𝑐 = 𝑇𝑎 +𝑅𝑛 − 𝐺
𝜌𝑐𝑃𝛾∗
∆ + 𝛾∗
𝑟𝑎 −𝑉𝑃𝐷
∆ + 𝛾∗
CANOPY TEMPERATURE
3
Canopy
resistance
(Clawson et al., 1989)
Radiative heating Evaporative
cooling
Air temp
Aerodynamic resistance
Highly non-linear, no analytical solution possible
Solving from an energy balance…
𝑟𝑎 = 𝑓 𝑤𝑖𝑛𝑑, ℎ𝑒𝑖𝑔ℎ𝑡, 𝐿𝐴𝐼, 𝑠𝑡𝑎𝑏𝑖𝑙𝑖𝑡𝑦 = 𝑓 𝑇𝑐
APPROACHES TO SIMULATE TC
1. Energy balance with stability corrections (EBSC)
2. Energy balance with neutral stability (EBN)
3. Empirical (EMP)
4
THE MODEL COMPARISON
1. Which Tc approach best simulates Tc?
2. Which Tc approach for best yield simulations?
3. Tc or Ta for best yield simulations?
5
OB
JEC
TIV
ES
METH
OD
S
Simulated HSC experiment in Arizona
• Spring wheat sown every 6-weeks
9 crop models
• Not a blind study
• Varying approaches to heat stress
• 3 approaches to model Tc (3 models each)
METHODS & SIMULATION STEPS
6
SET
1
SET
2
Models had all growth and develop data
2 sets of simulations
• Tc in heat stress response
• Ta in heat stress response
EVALUATION OF Tc SIMULATIONS
7
EMP
EBSC
EBN
ΔT
= T
c -
Ta
(Webber et al., in press)
EMP almost as
good as EBSC
WHICH TC APPROACH HAS BEST
YIELD SIMULATIONS?
EBN best results
8
DO BEST TC SIMULATIONS GIVE BEST
YIELD SIMULATIONS?
9
How do models get yield right if they have Tc wrong?
• Parameterization of heat stress response
DOES TC IMPROVE YIELD SIMULATIONS
WITH HEAT STRESS?
10
Most models show only modest improvement with Tc
ΔRMSE = RMSETa - RMSETc
SUMMARY
11
• Tc simulations
• EBSC best
• EMP also good
• Large bias in EBN
• No relationship skill in Tc & yield simulations
• Modest improvement in yield simulation with Tc
Next steps? • Critical examination of heat stress responses &
parameterization
• Perform across environments & conditions
• Assess mechanisms for Tc response
.012 Séminaire « Recherche et adaptation au changement climatique »
10 et 11 mars 2016
P. Martre / Impact model uncertainty and multi-models ensemble
P.R. Rötter, D.B. Lobell, D. Cammarano, A. Maiorano, B.A. Kimball, M.J. Ottman, G.W. Wall, J.W. White,
M.P. Reynolds, P.D. Alderman, P.V.V. Prasad, P.K. Aggarwal, J. Anothai, B. Basso, A. Berger, M. Bindi, C.
Biernath, A.J. Challinor, G. De Sanctis, J. Doltra, E. Fereres, R. Ferrise, M. Garcia-Vila, S. Gayler, G.
Hoogenboom, L.A. Hunt, R.C. Izaurralde, M. Jabloun, C. Jones, C. Kersebaum, A.-K. Koehler, C. Müller,
N.K. Soora, C. Nendel, G.J. O’Leary, J.E. Olesen, T. Palosuo, J.R. Porter, E. Priesack, E. Eyshi Rezaei,
A.C. Ruane, M.A. Semenov, I. Shcherbak, C. Stöckle, P. Stratonovitch, T. Streck, I. Supit, F. Tao, P.
Thorburn, K. Waha, E. Wang, D. Wallach, H. Webber, J. Wolf, Z. Zhao, Y. Zhu
Senthold Asseng, Frank Ewert, Pierre Martre
The AgMIP-Wheat Team https://www.agmip.org/wheat/