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
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
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.
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
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).
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
ITV & DTR changes The extremes
ITD99 ITD01 DTR99
c CDSPY14 Fig. SM2.
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
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
+ε
c CDSPY14 Fig. 3.
Links with other variables
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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)
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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 (%)
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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)
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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
0.680.46 0.6
0 2 4 6 8
−100102030
∆DTR vs. ∆T (K)
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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 (%)
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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
Observational constraints?
EOBS
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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
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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
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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
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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
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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
0.520.57 0.53
0.4 0.6 0.8 1.0
∆DTR vs. <DTR,T>
SRB/MTE
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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.
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