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/