SOUTH AMERICAN CLIMATE SOUTH AMERICAN CLIMATE DYNAMICS - A GENERAL VIEWDYNAMICS - A GENERAL VIEW

Tércio AmbrizziDepartment of Atmospheric Sciences

University of São Paulo

1ST IBERO-AMERICAN WORKSHOP ON CLIMATE DYNAMICS, CLIMATE CHANGE AND REGIONAL

CLIMATE MODELINGSão Paulo, Brazil

August 2007

Wind vector at high levels

Water vapor

DJF Main Observed and Simulated Global Teleconnection Patterns

JJA Main Observed and Simulated Global Teleconnection Patterns

TROPICAL CONVECTION AND ROSSBY WAVE GENESIS

Madden e Julian Oscillation and the generation of Rossby Wave

OLR

Wind Vector at 250 hPa

Intraseasonal Variability (MJO)

Composite evolution of 200-hPa velocity potential anomalies associated with MJO events and points of origin of tropical disturbances that developed into hurricanes or typhoons.

Precipitation anomaly

composites over the tropical Brazil associated to MJO

events

(mm)(Souza and Ambrizzi 2006)

Daily Meridional Wind Anomaly (250 hPa)

Rossby waves

Life cycle between 6 and 14+ days

(Average between 40S – 50S)

RAY TRACING - SACZ MODE - NORTH

10/20 days

20/30 days

30/70 days (Ferraz 2004)

OLR and wavenumbers 3, 4 e and 5 for each trajectory

ZCN 30/70DIA -20

200 hPa

850 hPa

ZCN 30/70DIA -18

200 hPa

850 hPa

ZCN 30/70DIA -16

200 hPa

850 hPa

ZCN 30/70DIA -14

200 hPa

850 hPa

ZCN 30/70DIA -12

200 hPa

850 hPa

ZCN 30/70DIA -10

200 hPa

850 hPa

ZCN 30/70DIA -08

200 hPa

850 hPa

ZCN 30/70DIA -06

200 hPa

850 hPa

ZCN 30/70DIA -04

200 hPa

850 hPa

ZCN 30/70DIA -02

200 hPa

850 hPa

ZCN 30/70DIA -01

200 hPa

850 hPa

ZCN 30/70DIA +0

200 hPa

850 hPa

ZCN 30/70DIA +01

200 hPa

850 hPa

ZCN 30/70DAY +02

200 hPa

850 hPa

(Ferraz 2004)

South Atlantic Convergence South Atlantic Convergence Zone Event – 21 a 28/01/1997Zone Event – 21 a 28/01/1997

Courtesy by Leila V. Carvalho

Day 21

Day 24

Day 22

Day 23

South Atlantic Convergence South Atlantic Convergence Zone Event – ContinueZone Event – Continue

Day 25

Day 28

Day 26

Day 27

Conceptual model of the SALLJ physical environment during the wet season (Marengo et al. 2004 - JC)

SALLJEX SALLJEX

Enhanced precipitation gauge network

NOAA/P-3 Missions

PIBALS Radiosondes

EXTREME PRECIPITATION EVENTS AND LLJ

1° Case: EPE + LLJ

2° Case: EPE + LLJ

3° Case: EPE + LLJ

4° Case: LLJ without EPE over the areas A1, A2 or A3

Weykamp (2006)

Divergence and Moisture flux integrated in the vertical

Weykamp (2006)

Some examples of each case for the 1998 summer

GOES 04/02/98 06Z

2

2) 04/02 LLJ (06 e 12Z) + EPE (A2)

GOES 21/02/98 06Z

3

3) 21/01 LLJ (06 e 12Z) + EPE (A3)

GOES 19/02/98 06Z

1) 19/02 LLJ (06Z) + EPE (A1)

1

4) 17/01 LLJ (12Z) without EPE

4

GOES 17/01/98 12Z

Weykamp (2006)

ATMOSPHERIC CIRCULATION SCHEMATIC PICTURES DURING CANONICAL EL NIÑO AND LA NIÑA

CANONICAL EL NIÑO

CANONICAL LA NIÑA

(Ambrizzi et al 2004)

INTER-EL NIÑOS VARIABILITY

I = (Xi - Xi)/i

ENSO episodes and the South American Regional Precipitation

Seasonal Standardized

index for the austral

summer (DJF) and

autumn (MAM)

were calculated for the

precipitation over key-

areas of South

America and the SSTa

over the Niño 1.2, 3,

3.4 and 4(Ambrizzi and Souza, 2003)

El Niño episodes and the South American Regional Precipitation during 1950-1990

(g)

-2,5

-1,5

-0,5

0,5

1,5

2,5

3,5

4,5

Ecuador/P eru

(f)

-2,5-1,5-0,50,51,52,53,54,5

Altiplano

(e)

-2,5-1,5-0,50,51,52,53,54,5

SE South America

(d)

-2,5-1,5-0,50,51,52,53,54,5

SACZ

(c)

-2,5-1,5-0,50,51,52,53,54,5

NE Brazil

(b)

-2,5-1,5-0,50,51,52,53,54,5

E Amazon

(a)

-2

-1

0

1

2

3

4

Niño 1+2 Niño 3 Niño 3+4 Niño 4

Niños SSTa

E Amazon

NE Brazil

SACZ

SE South America

Altiplano

Ecuador Peru

La Niña episodes and the South American Regional Precipitation during 1950-1990

(a)

-2

-1

0

1

2

3

4

Niño 1+2 Niño 3 Niño 3+4 Niño 4

(b)

-2,5-1,5-0,50,51,52,53,54,5

E Amazon

(c)

-2,5-1,5-0,50,51,52,53,54,5

NE Brazil

(d)

-2,5-1,5-0,50,51,52,53,54,5

SACZ

(e)

-2,5-1,5-0,50,51,52,53,54,5

SE South America

(f)

-2,5-1,5-0,50,51,52,53,54,5

Altiplano

(g)

-2,5

-1,5

-0,5

0,5

1,5

2,5

3,5

4,5

Ecuador/P eru

Niñas SSTa

E Amazon

NE Brazil

SACZ

SE South America

Altiplano

Ecuador Peru

SLC – PACIFIC BOXES - DEC - MAY – EL NIÑO

CB

E GSVD

(Coelho, Uvo and Ambrizzi, 2002 – TAC)

SSTa for 4 EL NIÑO EVENTS

El Niño 82/83 El Niño 86/87

El Niño 91/92 El Niño 97/98

Average over 4 events

(Drumond e Ambrizzi, 2003)

OMEGA ANOMALY

(Magaña e Ambrizzi 2005)

DJF ZONAL WIND AT 250 hPa

STREAMFUNCION ANOMALY AND RAY TRACING FOR 4 EL NIÑO EVENTS

Anomaly of Ψ

To identify the leading teleconnection patterns in the atmospheric circulation, Empirical Orthogonal Function (EOF) was applied to the monthly mean 700-hPa height anomalies poleward of 20° latitude for the Southern Hemisphere, for the period 1979 to 2000.

The loading pattern of AAO is defined as the first leading mode from the EOF analysis.

Monthly AAO indices are constructed by projecting the monthly mean 700-hPa height anomalies onto the leading EOF mode. Both time series are normalized by the standard deviation of the monthly index (1979-2000 base period).

DefinitionDefinition

AAO Positive FaseAAO Positive FaseClimate Prediction CenterClimate Prediction Center

Composites of SST and 200 hPa zonal wind (U200LF):Low-Frequency ( Retained Periods: above 365 days)

Negative AAO Phase Positive AAO Phase

U200U200LFLF U200U200LFLF

SSTSSTLFLF SSTSSTLFLF

(Carvalho, Jones, Ambrizzi, 2005 – JC)

Teleconnection Patterns of U200 (Wallace and Gutzler 1981)(The strongest negative correlation with grid points from 90S – 40S )

NEGATIVENEGATIVE

POSITIVEPOSITIVE

DIFFERENCEDIFFERENCE

Equatorward shift of the Subtropical Jet

Weakening Polar Jet

Strengthening of the Polar Jet Poleward shift

subtropical jet

Westerly jets can act as Rossby waveguides for propagation from tropics to midlatitudes

(Carvalho, Jones, Ambrizzi, 2005 – JC)

Precipitation AnomalyPrecipitation Anomaly (NCEP)

Summer Autumn Winter Spring

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (-) Summer

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (-) Autumn

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (-) Winter

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (-) Spring

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (+) Summer

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (+) Autumn

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (+) Winter

-3 -2.7-2.4-2.1-1.8-1.5-1.2-0.9-0.6-0.30 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

-80 -70 -60 -50 -40 -30 -20

-55

-50

-45

-40

-35

-30

-25

-20

-15

AAO (+) Spring

- AAO - AAO - AAO- AAO

+AAO+AAO+AAO+AAO

(Reboita, Ambrizzi & Rocha 2007)

REOF Precipitation anomalies DJF 1950 to 20014th rotated mode - 6.6% of the total variance

EN

EN EN

EN

LN LN

LNLN

LN LN LN

EN

EN

N N

N

1951/52, 1956/57, 1959/60, 1964/65, 1967/68, 1978/79, 1984/85, 1986/87, 1988/89

1957/58, 1970/71, 1972/73, 1976/77, 1980/81, 1983/84, 1997/98

ZCAS -

7 events

ZCAS +

9 events

Drumond (2005)

SACZ+ SACZ -

Composite of DJF precipitation anomalies (mm.day-1)

Composite of DJF SST anomalies (ºC)

Composite of DJF 200hPa anomalous zonally asymmetric component of stream function (x 106m2/s) anomaliesDrumond (2005)

Low Frequency SST Variability modes related to the South American Monsoon System

DJF SST Modes related to the SACZ -

Drumond (2005)

DJF SST Modes related to the SACZ +

Pm

Tm

Em

Em = Equatorial Mass

Tm = Tropical Mass

Pm = Polar Mass

SEASONAL CYCLONE TRACKS

SUMMER AUTUMN

WINTERSPRING

(Beu and Ambrizzi 2006)

CYCLONES, ANTICYCLONES AND COLD AIR MASS

(Pezza and Ambrizzi 2005)

Day -3

Day -2

Day -1

Day 0

Generalized Frost (+σ)

Phase coincidence

(Muller et al 2005)

The anomalous 250hPa meridional wind component

(ms-1)

(Muller and Ambrizzi 2007)

The anomalous 250hPa meridional wind component (ms-1) 14th day of integration

The importance of the phases coincidence:

Keeping the polar air advection over a large region Provoking an intense decrease in the surface temperature

Basic State +σ

Wind at 250 hPa

BETA

Ks

GF +σ GF -σ

(Muller and Ambrizzi 2007)

SST<0

H L

SST<0SST<0

H L

(Muller e Ambrizzi 2006)

SCHEMATIC CONCEPT OF POSSIBLE SCHEMATIC CONCEPT OF POSSIBLE GENERALIZED FROST MECHANISMGENERALIZED FROST MECHANISM

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