Climate prediction as a multiscale problem: from the diurnal scale to the multidecadal climate variability Pedro Leite da Silva Dias Laboratório Nacional de Computação Científica/MCTI Instituto de Astronomia, Geofísica e Ciêncas Atmosféricas/USP
Climate prediction as a multiscale problem: from the diurnal scale to the multidecadal climate variability
Pedro Leite da Silva Dias Laboratório Nacional de Computação Científica/MCTI
Instituto de Astronomia, Geofísica e Ciêncas Atmosféricas/USP
1. Goal : are models able reproduce interaction between diurnal/synoptic, intraseasonal, annual, interannual and decadal variability.
2. High resolution models is a solution - seamless prediction - costly!
1. Multiscaling modeling - understanding scale interactions –
non linear effects 1. Going from the diurnal to intraseasonal with atmospheric
models 2. Possible decadal signal in an atmospheric model with
parameterized diurnal heating 3. Simplified couples atmosphere/ocean models: 3 scale
interaction 2. Future.
Outline
The Last Millenium in South America
LIAMCA
600 800 1000 1200 1400 1600 1800 2000-7.5-7.0-6.5-6.0-5.5-5.0-4.5-4.0
Wet
Wet
Dry
δOSouthernBrazil
Years A.D
-7.6-7.8-8.0-8.2-8.4 δO C h i n a
600 800 1000 1200 1400 1600 1800 2000-0.5-1.0-1.5-2.0-2.5-3.0-3.5-4.0
δOFN1Nordeste
LIAMCA
600 800 1000 1200 1400 1600 1800 2000-7.5-7.0-6.5-6.0-5.5-5.0-4.5-4.0
Wet
Wet
Dry
δOSouthernBrazil
Years A.D
-7.6-7.8-8.0-8.2-8.4 δO C h i n a
600 800 1000 1200 1400 1600 1800 2000-0.5-1.0-1.5-2.0-2.5-3.0-3.5-4.0
δOFN1Nordeste
LIAMCA
600 800 1000 1200 1400 1600 1800 2000-7.5-7.0-6.5-6.0-5.5-5.0-4.5-4.0
Wet
Wet
Dry
δOSouthernBrazil
Years A.D
-7.6-7.8-8.0-8.2-8.4 δO C h i n a
600 800 1000 1200 1400 1600 1800 2000-0.5-1.0-1.5-2.0-2.5-3.0-3.5-4.0
δOFN1Nordeste
LIAMCA
600 800 1000 1200 1400 1600 1800 2000-7.5
-7.0
-6.5
-6.0
-5.5
-5.0
-4.5
-4.0
Wet
Wet
Dry
δ18O
Sout
hern
Braz
il
Years A.D
-7.6
-7.8
-8.0
-8.2
-8.4
δ18O
China
600 800 1000 1200 1400 1600 1800 2000-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
δ18O
FN1
Nor
dest
e
China
NE Brasil
SE Brasil
Dry
Wet
Cruz et al. 2011
Interesting point: •Mud data in Plata => Picomyo and Bermejo River - NW Argentina/Bolivia – summer rain
•Biased towards western part of the Plata •Need marker for the eastern •Different regimes E/W Plata Basin
Work in collaboration with IRD, INPE, USP, UFF,LNCC…
-3
-2
-1
0
1
2
3
1 13 25 37 49 61
-3
-2
-1
0
1
2
3
Northern Amazonia Rainfall Index (NAR)
Southern Amazonia Rainfall Index (SAR)
A
B
Marengo 2004
Herdies et al. 2001
(shaded)
Mean moisture flux and divergence in active and non active phases of the SACZ – 20-60 days.
A general problem with >15d forecasts and seasonal forecasts: • lack of power in the intraseasonal time scale
Power spectra of meridional wind at 40S , 60W – CPTEC – From seasonal forecasting model
S. Ferraz and P. Silva Dias – prep.
The Model for Prediction Across Scales • We are well advanced on developing the
next-generation Model for Prediction Across Scales
• Based on high spectral models or unstructured Voronoi (hexagonal) meshes and selective grid refinement (e.g., OLAM) with finite volume differencing scheme.
• To be utilized for weather, regional and global climate applications.
• Finite volume versions allows for non-hydrostatic (< 10 km horizontal resolution)
• Work towards exascale computing
Model Equations:
(1)
N =
u(x,y,t)
v(x,y,t)
Φ(x,y,t)
ξ =
Zonal and meridional Componentes of wind and geopotencial
0 0 FΦ(x,y,t)
F= --u∂u/∂x +v∂u/∂y
u∂v/∂x + v∂v/∂y
u∂φ/∂x +v∂φ/∂y + φ∇.V
Boundary conditions
Zonal periodicity: ξ (x+Lx,y,t)= ξ(x,y,t) (2)
ξ(x,y,t)→0 as y→±∞ (3)
• Shallow-Water model on the equatorial β-plane in the nondimension
form:
Linear operator Forcing terms Nonlinear
terms
Raupp, C. F. M. and Silva Dias, P. L. 2004,2005
Effect of basic flow of January climatology Source Modulation
00.5
11.5
22.5
33.5
0 2 3 4 6 7 8 10 11 12 14 15 16 18 19 20 22 23
Hour
Sour
ce a
mpl
itude
Question: is it possible for an inertio-gravity wave mode to significantly interact with a Rossby mode so as to lead the latter to undergo significant amplitude modulation?
Governing Equations –simple model with parameterized heat source
Two-layer incompressible equatorial primitive equations:
1111000 divVVVVpyV
tV
−∇•−=∇++∂∂ ⊥
0div 0 =V
0110111 VVVVpyV
tV
∇•−∇•−=∇++∂∂ ⊥
1010
22
2
11
2gπdiv pVS
TcNHV
tp
p
∇•−−=+∂∂
(1a)
(1b)
(1c)
(1d)
N ⇒ Brunt-Vaissala frequency (N ≈ 10-2 s-1 ⇒ Typical tropospheric value)
H ⇒ Top height of the Troposphere (H ≈ 16Km in the tropics);
g ⇒ gravity acceleration (g ≈ 10 ms-2 )
Cp ⇒ thermal capacity of dry air at constant pressure (Cp= 1004J/KKg);
T0 ≈ 15º C (reference value of temperature)
S1 ⇒ thermal forcing (parametric heat source)
Barotropic mode
First baroclinic mode
Example of nonlinear Resonance: Energy in gravity waves (diurnal) interacting with Rossby waves (synoptic) under proper large scale background field => intraseasonal modulation
Nonlinearity => energy transfer among scales Dynamics of resonant interaction through advection terms •Examples:
•Interaction between slow ( O(5-7days) ) and fast modes ( O(1 day or less) ) => intraseasonal scales (20-60 days) Raupp and Silva Dias. (2004,2005,2006, 2008)
•Importance of diurnal variation leading to energy in intraseasonal time scales (Raupp and Silva Dias, 2009,2010)
•Coupled ocean/atmosphere simplified models: interaction between intraseasonal scale ( O(20-60d) ) with interannual (El Nino/La Nina) - O (2-3 yr) => decadal/multidecadal time scales (Enver et al. 2009,2011)
model for studying multiscaling : from MJO to
Multidecadal variability
Search for Resonant Nonlinear
Interactions - physics coupling
Enver Ramirez ,Carlos Raupp and Pedro L. Silva Dias
Simplified coupled model resonant interaction: atmospheric Kelvin (moist)(green), Rossby atmosphere (dry – green) and ocean Kelvin (blue)
Simplified models are quite useful for understanding basic interaction mechanisms of the
ocean/atmosphere!!
Clearly show mechanisms responsible for diurnal to decadal variability!!!!!