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Projected increase in diurnal and inter-diurnal variations of European summer temperatures

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Projected increase in diurnal and inter-diurnal variations of European summer temperatures

Julien Cattiaux, Hervé Douville, Robert Schoetter

CNRM-GAME, CNRS/Météo-France, Toulouse, France.

Sylvie Parey

EDF R&D, Chatou, France.

Pascal Yiou

LSCE-IPSL, CNRS/CEA/UVSQ, Gif-sur-Yvette, France.

AGU Meeting

San Francisco, Dec 16, 2014

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Previously in European summer temperature variability

I Evidences for increase at intra-seasonal and/or inter-annual time scales:

- in recent observations – Parey et al. 2010, Schär et al. 2004, Yiou et al. 2009 ; - in regional climate projections – Fischer and Schär 2009, Kjellström et al. 2007 ; - in CMIP3 global climate projections – Cattiaux et al. 2011 .

I Suggested physical mechanisms:

- soil-atmosphere processes associated with the European summer drying;

- changes in the atmospheric circulation;

- . . .

I Some key challenges:

- identify all drivers and quantify their contributions;

- understand the model discrepancies in future projections;

- investigate observational constraints to reduce future uncertainties.

J. Cattiaux et al. - European summer temperature variability in CMIP5 AGU Meeting - Dec 2014

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What we did

I Focus on day-to-day and within-day variations (E3P project):

- Inter-diurnal temperature variability:

ITV = 1 n

d

− 1

nd−1

X

d=1

|ITD

d

| = 1 n

d

− 1

nd−1

X

d=1

|T

d+1

− T

d

|

- Diurnal temperature range:

DTR

d

= T

dx

− T

dn

.

I Data:

- 34 CMIP5 models, historical and future simulations (3 RCPs);

- changes assessed as differences between 1979–2008 and 2070–2099;

- EOBS temperatures for evaluation over 1979–2008;

- 10 historical runs of CNRM-CM5 for internal variability.

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Why ITV?

I Day-to-day absolute variations are linked to the daily variance:

|ITD d | = |T d+1 − T d | = √ 2 σ(T

J d,d+1 K )

I Contrarily to the variance, the ITV is not sensitive to long-term variations:

0 20 40 60 80 100

−4

−2 0 2

4 Time series: N(0,1)

0 20 40 60 80 100

0.5 1.0 1.5 2.0

2.5 Running variance Running mean of ITV^2/2

0 20 40 60 80 100

−4

−2 0 2

4 N(0,1) + TREND

0 20 40 60 80 100

0.5 1.0 1.5 2.0

2.5 Running variance Running mean of ITV^2/2

0 20 40 60 80 100

−4

−2 0 2

4 N(0,1) + CYCLE

0 20 40 60 80 100

0.5 1.0 1.5 2.0

2.5 Running variance Running mean of ITV^2/2

Based on 1000 random simulations of white noises.

J. Cattiaux et al. - European summer temperature variability in CMIP5 AGU Meeting - Dec 2014

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ITV & DTR changes The mean

EOBS

CNRM

MIROCc INM

1.0

1.2 1.4 1.6 1.8 2.0 2.2

ITV (K)

EOBS CNRM

MIROCc INM

6

8 10 12 14 16

DTR (K) IPSL CSIRO

IPSLb CSIRO

BNU

ACCS0

−10 0 10 20

∆ITV (%)

NCC CSIRO

MRI CSIRO

MRI ACCS0

−5 0 5 10 15 20 25

∆DTR (%)

50%

25%

75%

5%

95%

HIST(30) R2.6(19) R4.5(27) R8.5(30)

50%

25%

75%

5%

95%

HIST(33) R2.6(21) R4.5(29) R8.5(33)

c CDSPY14 Fig. 1.

I Consistent with Kim et al. 2013 & Lindvall and Svensson 2014 (global).

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ITV & DTR changes The pdf

Density 0.000.050.100.150.200.25

ITD pdf EOBS (K)

−12 −8 −5 −2 1 3 5 7

Density 0.000.020.040.060.080.10

DTR pdf EOBS (K)

0 3 6 9 12 15 18 21 EOBS

CNRM

T p

1.52.02.53.0

σ (K)

EOBS CNRM

q p

23456789

σ (K) q f

r f

r f

0.00.20.40.6

∆σ (K)

w f

w a

w a

−0.20.00.20.40.6

∆σ (K)

EOBS

CNRM

a T

−1.0−0.8−0.6−0.4−0.2

γ

EOBS

CNRM r g

−0.4−0.20.00.20.4

γ s q

s r

A q

−0.2−0.10.00.10.2

∆γ

f q

f q

f q

−0.4−0.20.00.2

∆γ

50%

25%

75%

5%

95%

HIST(31) R2.6(19) R4.5(27) R8.5(31)

c CDSPY14 Fig. 2.

J. Cattiaux et al. - European summer temperature variability in CMIP5 AGU Meeting - Dec 2014

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ITV & DTR changes The extremes

ITD99 ITD01 DTR99

c CDSPY14 Fig. SM2.

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Contribution of the North-Atlantic dynamics Methodology I For X the ITV or DTR: X = P

k f k · x k = P

k f k · Φ(z k ).

f k → z k

↓ Φ

x k

Data: Z500 NCEP2 & DTR EOBS | Methodology: Cattiaux et al., 2013, Climate Dynamics.

J. Cattiaux et al. - European summer temperature variability in CMIP5 AGU Meeting - Dec 2014

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Contribution of the North-Atlantic dynamics Results

I For X the ITV or DTR: X = P

k f k · x k = P

k f k · Φ(z k ).

∆X = X

k

∆f k · Φ(z k ) + X

k

f k · Φ(∆z k )

| {z }

Weather Regimes (WR)

+ X

k

f k · ∆Φ(z k )

| {z }

Non WR

c CDSPY14 Fig. 3.

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Links with other variables

a A B b

c d e

f g h

H l m

n o p

q Q

r s

tT U u v V

w y x z

0 2 4 6 8

−100102030

∆ITV vs. ∆T (K)

● ●

a

A B b

c d

e f

g

h H m o n p

q Q

r s tT U u

v V

w x y

z

−0.73

−0.78

−0.77

−30 −20 −10 0 5

∆ITV vs. ∆EF (%)

a A

B b c d

e f

g h

H m l n o p q

Q

r s

t T

u U v V

w y x z

0.72 0.54

−3 −2 −1 0 1

−100102030

∆ITV vs. ∆SLP (hPa)

●●

a A b B

c d

e

f g h

H i

j k

l m n p o

q Q r s tT U u v V

w y x z

0.68

0.46 0.6

0 2 4 6 8

−100102030

∆DTR vs. ∆T (K)

● ●

a

A b B

c d

e f g

h H i

j m

n p o

Q q r

s tT U u

V v

w x y

z

−0.67

−0.68

−0.7

−30 −20 −10 0 5

∆DTR vs. ∆EF (%)

● ●

a A

b B

c d

e g f

h H p i Q q r t s T U u

V v

w x y

z

−0.54

−0.46

−0.62

−40 −20 0 20

−100102030

∆DTR vs. ∆CRE (%)

c CDSPY14 Fig. 4.

J. Cattiaux et al. - European summer temperature variability in CMIP5 AGU Meeting - Dec 2014

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Observational constraints?

EOBS

● ●

a A

b B

c d e

f g

h H

l m

no

p q

Q

r s T t

U u v V

w y x z

0.8 1.2 1.6 2.0

−100102030

∆ITV vs. ITV (K)

EOBS

a A

b B c d

e f

g h H n l m o

p q Q

r s t T

U u v V

w x y z

0.5 0.49 0.55

−0.4 0.0 0.2 0.4 0.6 0.8

∆ITV vs. <ITV,T>

SRB/MTE

a A B b

c d e f g

h H

m

n o

p

q Q

r s T t u U

v V

w y x

z

−0.5

−0.54

−0.55

−0.8 −0.4 0.0 0.4 0.8

−100102030

∆ITV vs. msoil

EOBS

●●

a A b B c

d

e g f h H i

j k

l m n

o p

q Q r t s T

U u V v

w x y z

6 8 10 12 14 16 18

−100102030

∆DTR vs. DTR (K)

EOBS

a A b B c d

e

f g

h H i

j k

l m n p o

Q q r

t s T U u

V v

w

x y z

0.52

0.57 0.53

0.4 0.6 0.8 1.0

∆DTR vs. <DTR,T>

SRB/MTE

a A b B

c d

e g f

h H

i j

m n p o

Q q r s T t u U

v V

w y x

z

−0.46

−0.45

−0.8 −0.4 0.0 0.4 0.8

−100102030

∆DTR vs. msoil

c CDSPY14 Fig. 4.

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Summary

X Increase in short-term European summer temperature variability.

X Widening of the ITV distribution vs. shift of the DTR distribution.

X Both ITV and DTR increases associated with soil drying.

X Among other processes: circulation (ITV), cloudiness reduction (DTR).

X Emerging constraints in inter-annual present-day correlations.

−→ Detection and attribution of present-day trends?

−→ Sensitivity experiments to confirm the drivers?

−→ Role of horizontal temperature gradients (e.g. land-sea warming ratio)?

Cattiaux, J., H. Douville, R. Schoetter, S. Parey and P. Yiou (2014), Projected increase in diurnal and inter-diurnal variations of European summer temperatures, Geophys. Res. Lett., accepted.

J. Cattiaux et al. - European summer temperature variability in CMIP5 AGU Meeting - Dec 2014

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