SOUTH AMERICAN CLIMATE DYNAMICS - A GENERAL VIEW Trcio AmbrizziDepartment of Atmospheric Sciences University of So Paulo

1ST IBERO-AMERICAN WORKSHOP ON CLIMATE DYNAMICS, CLIMATE CHANGE AND REGIONAL CLIMATE MODELINGSo Paulo, Brazil August 2007

Wind vector at high levelsWater 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 WaveOLRWind 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 wavesLife 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

(Ferraz 2004)

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

South Atlantic Convergence Zone Event ContinueDay 25Day 28Day 26Day 27

SALLJEX Enhanced precipitation gauge networkNOAA/P-3 MissionsPIBALSRadiosondes

EXTREME PRECIPITATION EVENTS AND LLJ1 Case: EPE + LLJ2 Case: EPE + LLJ3 Case: EPE + LLJ4 Case: LLJ without EPE over the areas A1, A2 or A3Weykamp (2006)

Divergence and Moisture flux integrated in the verticalWeykamp (2006)

Some examples of each case for the 1998 summerWeykamp (2006)

ATMOSPHERIC CIRCULATION SCHEMATIC PICTURES DURING CANONICAL EL NIO AND LA NIACANONICAL EL NIOCANONICAL LA NIA(Ambrizzi et al 2004)

INTER-EL NIOS VARIABILITY

ENSO episodes and the South American Regional PrecipitationSeasonal 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 Nio 1.2, 3, 3.4 and 4(Ambrizzi and Souza, 2003)

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

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

SLC PACIFIC BOXES - DEC - MAY EL NIOCBEGSVD(Coelho, Uvo and Ambrizzi, 2002 TAC)

SSTa for 4 EL NIO EVENTSEl Nio 82/83El Nio 86/87El Nio 91/92El Nio 97/98Average over 4 events(Drumond e Ambrizzi, 2003)

OMEGA ANOMALY(Magaa e Ambrizzi 2005)

DJF ZONAL WIND AT 250 hPa

STREAMFUNCION ANOMALY AND RAY TRACING FOR 4 EL NIO EVENTS Anomaly of

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).DefinitionAAO Positive FaseClimate Prediction Center

Composites of SST and 200 hPa zonal wind (U200LF):Low-Frequency ( Retained Periods: above 365 days)Negative AAO PhasePositive AAO Phase U200LFU200LFSSTLFSSTLF(Carvalho, Jones, Ambrizzi, 2005 JC)

Teleconnection Patterns of U200 (Wallace and Gutzler 1981)(The strongest negative correlation with grid points from 90S 40S ) NEGATIVEPOSITIVE DIFFERENCE Equatorward shift of the Subtropical JetWeakening 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 (NCEP)SummerAutumnWinterSpring- 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 varianceENENENENLNLNLNLNLNLNLNENENNNN1951/52, 1956/57, 1959/60, 1964/65, 1967/68, 1978/79, 1984/85, 1986/87, 1988/891957/58, 1970/71, 1972/73, 1976/77, 1980/81, 1983/84, 1997/98ZCAS -7 eventsZCAS +9 eventsDrumond (2005)

SACZ+SACZ -Composite of DJF precipitation anomalies (mm.day-1)Composite of DJF SST anomalies (C)Composite of DJF 200hPa anomalous zonally asymmetric component of stream function (x 106m2/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 +

PmTmEmEm = Equatorial MassTm = Tropical MassPm = Polar Mass

SEASONAL CYCLONE TRACKSSUMMERAUTUMNWINTERSPRING(Beu and Ambrizzi 2006)

CYCLONES, ANTICYCLONES AND COLD AIR MASS(Pezza and Ambrizzi 2005)

Day -3Day -2Day -1Day 0Generalized Frost (+)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 integrationThe importance of the phases coincidence:

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

Wind at 250 hPaBETAKsGF + GF - (Muller and Ambrizzi 2007)

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

GRUPO DE ESTUDOS CLIMTICOSTHANKS FOR BEING HERE !!!

WELCOME TO SO PAULO CITY, BRAZILCLIMATE STUDIES GROUP

There is strong evidence that the MJO modulates the activity of tropical cyclones during the NH warm season by providing a large-scale environment that is either favorable or unfavorable for development. The strongest tropical cyclones tend to develop when the MJO favors enhanced precipitation. As the MJO progresses eastward, the favored region for tropical cyclone activity also shifts eastward from the western Pacific to the eastern Pacific and finally to the Atlantic. While this relationship appears robust, the MJO is one of many factors (e.g. SST conditions, vertical wind shear) that contribute to the development of tropical cyclones. A variarity of works were presented at the Conference not only dealing with SALLJ but also with different aspects of the climate system over South America, specially east of the Andes. The Conference consisted of around 50 presentations and 4 plenary discussions. In particular discussions during the plenary session were mostly concentrated on integrating the different results and conclusions made in the oral presentations in a single conceptual model of the SAMS rather to identify gaps of knowledge. Here we have an scheme made by Jose Marengo where the different elements acting on the moisture transport between tropics and extratropics are present. On a large scale, easterly trade winds transport moisture into the continent. Amazon region is considered as a source of moisture too and it should be included too the moisture transport entering from the Atlantic ocean. We will see later that its penetration further west and further south is strongly modulated on synoptic, intraseasonal and even interannual timescales. Then moisture is mainly advected along the eastern slope of the Andes to the south and near the Andes elbow a maximum of the low-level winds are observed where very often are detected episodes of LLJ. The definition of LLJ is related with the mesoscale characteristics of the flow as its intensity and shear however this name has been extended by the VAMOS community to identify, from a large-scale perspective, the moisture corridor that flows to the south. Moisture convergence occurs over la Plata basin and enhanced precipitation is observed mostly due to mesoscale convective system activity. In this picture it is particularly noticeable the interaction between Amazon and la Plata basins. So, in the rest of my presentation I will briefly describe some of the main conclusions arosed at the Conference about the SALLJ characterization, theories of SALLJ generation and variability. Numerical simulation of the South American Monsoon System. The role of SALLJ on precipitation development and Links between tropical and subtropical climate variability.