Towards a better understanding of changes in European temperature extremes

Towards a better understanding of changes in European temperature extremes

A multi-model analysis from CMIP5/CFMIP2

Julien Cattiaux, Hervé Douville, Aurélien Ribes and Fabrice Chauvin.

CNRM/Météo-France, Toulouse, France.

January 25, 2012

J. Cattiaux et al. (CNRM) CNRM

Motivations

Temperature extremes?

Extremely warm/cold days: Tmax/Tmin above/below the 90^th/10^th centile of a reference pdf (e.g., observations or historicalruns).

Highest impacts, responses not necessarily scaled on the mean.

Questions

Uncertainties in GCMs: Large-scale circulation? Soil processes?

Cloud feedbacks?

How to separate dynamical vs. non-dynamical contributions?

Multi-model data (9 GCMs so far)

CMIP5: historical(1979–2008) &rcp85(2070–2099): 8 GCMs.

CFMIP2: amip&amipFuture: 4 GCMs.

J. Cattiaux et al. (CNRM) CNRM

Motivations

Temperature extremes?

Extremely warm/cold days: Tmax/Tmin above/below the 90^th/10^th centile of a reference pdf (e.g., observations or historicalruns).

Highest impacts, responses not necessarily scaled on the mean.

Questions

Uncertainties in GCMs: Large-scale circulation? Soil processes?

Cloud feedbacks?

How to separate dynamical vs. non-dynamical contributions?

Multi-model data (9 GCMs so far)

CMIP5: historical(1979–2008) &rcp85(2070–2099): 8 GCMs.

CFMIP2: amip&amipFuture: 4 GCMs.

J. Cattiaux et al. (CNRM) CNRM

Motivations

Temperature extremes?

Extremely warm/cold days: Tmax/Tmin above/below the 90^th/10^th centile of a reference pdf (e.g., observations or historicalruns).

Highest impacts, responses not necessarily scaled on the mean.

Questions

Uncertainties in GCMs: Large-scale circulation? Soil processes?

Cloud feedbacks?

How to separate dynamical vs. non-dynamical contributions?

Multi-model data (9 GCMs so far)

CMIP5: historical(1979–2008) &rcp85(2070–2099): 8 GCMs.

CFMIP2: amip&amipFuture: 4 GCMs.

J. Cattiaux et al. (CNRM) CNRM

Future changes in wintertime cold days

Probability of exceedingQ₁₀^historical inrcp85(PQ10)

J. Cattiaux et al. (CNRM) CNRM

Future changes in wintertime cold days

Probability of exceeding Q₁₀^amip in amipFuture(PQ10)

J. Cattiaux et al. (CNRM) CNRM

European temperatures & North-Atlantic dynamics

Weather regimes

Clustering of daily Z500anomalies. (e.g., Michelangeli et al., 1995)

Temperatures well discriminated among the 4 classical regimes.

PQ10=P

kP(Ωk)·P(T <T10|Ωk).

Z500(NCEP2)

PQ10 (E-OBS)

J. Cattiaux et al. (CNRM) CNRM

Future changes in mean Z500

Z500, DJFM,rcp85−historical

J. Cattiaux et al. (CNRM) CNRM

Future changes in mean Z500

Z500, DJFM,amipFuture−amip

J. Cattiaux et al. (CNRM) CNRM

Evaluating dynamical contributions

Contribution of changes in regimesfrequencies:

X =X

k

fkxk ⇒ ∆^F−PX = X^F−X^P=X

k

f_k^Fx_k^F−X

k

f_k^Px_k^P

= X

k

∆fk·x_k^P

| {z }

BC

+X

k

f_k^P·∆xk

| {z }

WC

+X

k

∆fk·∆xk

| {z }

RES

Contribution of changes in regimesstructures:

∀k x_k= Φ(dk) ⇒ ∆xk= Φ^F(d_k^F)−Φ^P(d_k^P) = [Φ^F(d_k^F)−Φ^P(d_k^F)]+[Φ^P(d_k^F)−Φ^P(d_k^P)]

Final breakdown

∆^F−PX =X

k

∆f_k·Φ^P(d_k^P)

| {z }

BC

+X

k

f_k^P·Φ^P(∆d_k)

| {z }

WCd

+X

k

f_k^P·∆Φ(d_k^F)

| {z }

WCΦ

+RES

Cattiaux et al.,SI Clim. Dyn., submitted.

J. Cattiaux et al. (CNRM) CNRM

Evaluating dynamical contributions

Contribution of changes in regimesfrequencies:

X =X

k

fkxk ⇒ ∆^F−PX = X^F−X^P=X

k

f_k^Fx_k^F−X

k

f_k^Px_k^P

= X

k

∆fk·x_k^P

| {z }

BC

+X

k

f_k^P·∆xk

| {z }

WC

+X

k

∆fk·∆xk

| {z }

RES

Contribution of changes in regimesstructures:

∀k x_k= Φ(dk) ⇒ ∆xk= Φ^F(d_k^F)−Φ^P(d_k^P) = [Φ^F(d_k^F)−Φ^P(d_k^F)]+[Φ^P(d_k^F)−Φ^P(d_k^P)]

Final breakdown

∆^F−PX =X

k

∆f_k·Φ^P(d_k^P)

| {z }

BC

+X

k

f_k^P·Φ^P(∆d_k)

| {z }

WCd

+X

k

f_k^P·∆Φ(d_k^F)

| {z }

WCΦ

+RES

Cattiaux et al.,SI Clim. Dyn., submitted.

J. Cattiaux et al. (CNRM) CNRM

Evaluating dynamical contributions

Contribution of changes in regimesfrequencies:

X =X

k

fkxk ⇒ ∆^F−PX = X^F−X^P=X

k

f_k^Fx_k^F−X

k

f_k^Px_k^P

= X

k

∆fk·x_k^P

| {z }

BC

+X

k

f_k^P·∆xk

| {z }

WC

+X

k

∆fk·∆xk

| {z }

RES

Contribution of changes in regimesstructures:

∀k x_k= Φ(dk) ⇒ ∆xk= Φ^F(d_k^F)−Φ^P(d_k^P) = [Φ^F(d_k^F)−Φ^P(d_k^F)]+[Φ^P(d_k^F)−Φ^P(d_k^P)]

Final breakdown

∆^F−PX =X

k

∆f_k·Φ^P(d_k^P)

| {z }

BC

+X

k

f_k^P·Φ^P(∆d_k)

| {z }

WCd

+X

k

f_k^P·∆Φ(d_k^F)

| {z }

WCΦ

+RES

Cattiaux et al.,SI Clim. Dyn., submitted.

J. Cattiaux et al. (CNRM) CNRM

Evaluating the term Φ

^P

(d

_k^F

)

I.e. the mean value of X that would produce present-day physics from future circulations.

One way to do it: consider

Φ^P(d_k^F)≡Φ^P(df_k^P) ,

where df_k^P are the flow-analogs ofd_k^F sampled among the present-day circulations d_k^P.

—

See, e.g., Lorenz (1969) for flow-analogs.

−2 −1 0 1 2

−2

−1 0 1 2

EOF1

EOF2

●

●

●

●

●

●

●

● ●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●●

●

●

● ●

●●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

● ● ●

●

●

●

●

●

●

●

● ●

●●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●● ●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

● ●

●

● ●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

● ●

●

● ●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●●

●

● ●

●

●

●

●

●

● ●

● ●

●

●

●

●

●

● ●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

● ●

●

●

●

●

●

●●

●

● ●

●

●

●

● ●

●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

● ●

● ●

●

●

●

●

●

●

●

●

●

●● ●●

●

● ●

● ●

●

●●

●

●

●

● ● ●

● ●

●

●

●

●

●

●

●

●

●●

●

●

●●

● ●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

● ●● ●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

● ●

●

● ●

●

●

●●

●

●

●

●

● ●

●

●

●

●

●

● ●

●

●

●

●

●pre

Cattiaux et al.,SI Clim. Dyn., submitted.

J. Cattiaux et al. (CNRM) CNRM

Evaluating the term Φ

^P

(d

_k^F

)

I.e. the mean value of X that would produce present-day physics from future circulations.

One way to do it: consider

Φ^P(d_k^F)≡Φ^P(df_k^P) ,

where df_k^P are the flow-analogs ofd_k^F sampled among the present-day circulations d_k^P.

—

See, e.g., Lorenz (1969) for flow-analogs.

−2 −1 0 1 2

−2

−1 0 1 2

EOF1

EOF2

●

●

●

●

●

●

●

● ●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●●

●

●

● ●

●●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

● ● ●

●

●

●

●

●

●

●

● ●

●●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●●● ●

●

● ●● ●

●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

●

●● ●

●

●

●

● ●

●

●

●

●

●●

●

●

●

●

●

●

● ● ●

● ●

●

●

●

●

●● ●

●

●

●

●

●

●

●

● ●●●

●

●

●

●

●

●

●

●

●

● ●

●

● ●● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

● ●

●

● ●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

● ●

●

● ●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ● ●

●

● ●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●●

● ●

●

●

●

●

●

●

●

●

●

●

● ●●

●

●

●

●

●

●

●

●

●

●●

●

●

●

●

● ●

●

●●

●

●

● ●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●●

●

● ●

●

●

●

●

●

● ●

● ●

●

●

●

●

●

● ●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

● ●

●

●

●

●

●

●●

●

● ●

●

●

●

● ●

●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

● ●

● ●

●

●

●

●

●

●

●

●

●

●● ●●

●

● ●

● ●

●

●

●

●

●

● ●

●

●

●

●

●

●

●●

●

●

●

●

● ●

●

● ●

●

●

●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

● ● ●

● ●

●

●

●

●

●

●

●

●●

●

●

●

● ● ●

● ●

●

●

●

●

●

●

●

●

●●

●

●

●●

● ●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

● ●● ●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

●

●

●

●

●

● ●

●

● ●

●

●

●●

●

●

●

●

● ●

●

●

●

●

●

● ●

●

●

●

●

● ●

●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●●

●

●

●●

●

●

●

●

●

●

●

●

●

●

●

●

● ●

●

● ●

●

●

●

●

●

●

● ●

●

● ●

●

●

●

● ●

●

●

●

●

●

●

●

●

●

● ●

●●

●

●

●

●

●

●

●●

●

●

●

●

●

●

●

● ●

●

● ●

●

●

● ●

● ●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

pre fut

Cattiaux et al.,SI Clim. Dyn., submitted.

J. Cattiaux et al. (CNRM) CNRM