SOUTH AMERICAN CLIMATE DYNAMICS - A GENERAL VIEW Tércio Ambrizzi Department of Atmospheric Sciences University of São Paulo 1 ST IBERO-AMERICAN WORKSHOP ON CLIMATE DYNAMICS, CLIMATE CHANGE AND REGIONAL CLIMATE MODELING São 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 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DIA hPa 850 hPa ZCN 30/70 DAY hPa 850 hPa (Ferraz 2004)

South Atlantic Convergence Zone Event – 21 a 28/01/1997 Courtesy by Leila V. Carvalho Day 21 Day 24 Day 22 Day 23

South Atlantic Convergence Zone Event – Continue Day 25 Day 28 Day 26 Day 27

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

SALLJEX Enhanced precipitation gauge network NOAA/P-3 Missions PIBALSRadiosondes

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 = (X i - X i )/  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 Niños SSTa E Amazon NE Brazil SACZ SE South America Altiplano Ecuador Peru

La Niña episodes and the South American Regional Precipitation during Niñas SSTa E Amazon NE Brazil SACZ SE South America Altiplano Ecuador Peru

SLC – PACIFIC BOXES - DEC - MAY – EL NIÑO C B EG SVD (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  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 ( base period). Definition AAO Positive Fase Climate Prediction Center

Composites of SST and 200 hPa zonal wind (U200LF): Low-Frequency ( Retained Periods: above 365 days) Negative AAO PhasePositive AAO Phase U200 LF SST LF (Carvalho, Jones, Ambrizzi, 2005 – JC)

Teleconnection Patterns of U200 (Wallace and Gutzler 1981) (The strongest negative correlation with grid points from 90S – 40S ) NEGATIVE POSITIVE DIFFERENCE  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 Anomaly Precipitation Anomaly (NCEP) Summer Autumn Winter Spring - AAO +AAO (Reboita, Ambrizzi & Rocha 2007)

REOF Precipitation anomalies DJF 1950 to th rotated mode - 6.6% of the total variance EN LN EN N N N 1951/52, 1956/57, 1959/60, 1964/65, 1967/68, 1978/79, 1984/85, 1986/87, 1988/ /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 10 6 m 2 /s) anomalies Drumond (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 WINTER SPRING (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)

(Muller e Ambrizzi 2006) SCHEMATIC CONCEPT OF POSSIBLE GENERALIZED FROST MECHANISM

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