Centro Internacional para la Investigación del Fenómeno de El Niño I FORO DE PERSPECTIVAS CLIMÁTICAS PARA SUDAMÉRICA Guayaquil - Ecuador, 01 al 04 de Octubre 2012 Seminario - Taller Clima de Sud América Sintesis del clima actual en Sud América Relator: Dr. René D. Garreaud Departamento de Geofísica Universidad de Chile

All stations (anytime, any length) Century-long stations (Ti 1995, missdata<20%) Precipitation Mean Temperature Global Historical Climate Network (GHCN)

Altiplano Subtropical Andes Amazon basin La Plata basin Brazilian highlands Chaco Pampas Patagonia Equatorial Andes Llanos Guinas highlands Geographical setting 10°N 0°N 20°S 40°S 60°S

General circulation in an aqua-planet Perpetual Equinox 0° 45° NE trades SE trades ITCZ: Intertropical Convergence Zone Belt of higher pressure Tropical Tropopause (15 km) Belt of lower pressure Surface westerlies Surface wind (arrows) Precipitation (green shadow)

0° 60° General circulation in an aqua-planet Perpetual Equinox Jet stream (westerly flow) aloft (10-12 km): long term mean. Boundary between subtropical and extratropical air masses ITCZ Midlatitude precipitation maximum and westerly belt

Because of its long meridional extent, South America exhibits tropical, subtropical and extratropical climatic regimes

120°W 90°W 60°W 30°W 60°S 30°S 0°S S. Atlantic Anticyclone Midlatitude Storm track Continental Low Level Jet SE Pacific Anticyclone Midlat. Precip. Tropical rainfall SCu & Cold SST The big picture

Zonal wind just upstream of the Andes (over the SE Pacific)

Cold tongue Warm Pool Oceanic boundary conditions

DJF MAM JJA SON Seasonal long-term mean 2-m air temperature [°C] U. Delaware

The low-level air temperature field

DJF MAM JJA SON Seasonal long-term mean Precipitation [mm/day] U. Delaware

Precipitation features 1. ITCZ 2. Continental convection 3. Altiplano convection 4. SACZ 5. Pampas convection 6. Midlatitude storm track 7. Orographic precipitation 8. Coastal desert 9. NE Brazil semiarid 10. Patagonia dry zone 11. Ocean desert Circulation features 1. ITCZ 2. Trade winds 3. Subtropical high 4. Midlatitude westerlies 5. Low level jet 6. SACZ 7. Bolivian high 8. NE Brazil trough 9. Tropical easterlies 10. Midlatitude westerlies 11. Jet stream

Annual Mean / Zonal MeanAnnual Mean / Zonal asymmetryJanuary - July Mean Another Perspective of the Precipitation Field

Vera et al (BAMS) Southeast South America Precipitation (warm season)

Iracema Fonseca Albuquerque Cavalcanti South Atlantic Convergence Zone

Convective rainfall also exhibits a pronounced diurnal cycle

Northerly low level jet interrupted by cold air incursions that reach as far as the Amazon basin

a. Zonal wind speed W E Pressure [hPa] b. Near surface mixing ratio and OLR over the Altiplano W/m 2 g/Kg Reanalysis data at 17.5°S 70°W Precipitación Altiplano Precipitation: annual cycle

a. Zonal wind speed W E Pressure [hPa] b. Near surface mixing ratio and OLR W/m 2 g/Kg Altiplano Precipitation: intraseasonal variability

Anomalies of wind aloft forced by extratropical disturbances Wind aloft controls the transport of moisture towards the Altiplano Altiplano Precipitation: conceptual model (summer)

B A Frio Cálido 500 hPa Las perturbaciones de latitudes medias (ver clase anterior) también transportan calor hacia latitudes altas, continuando el proceso de transferencia de calor que realiza la atmósfera. Precipitación en latitudes medias

El mecanismo más simple es la saturación de vapor de agua, y posterior formación de partículas de precipitación, en flujos estables ladera arriba al barlovento de la topografía. Precipitación Orografíca (latitudes medias)

De todas las variables probados, es el flujo de vapor de agua en la dirección zonal (hacia la Cordillera) a 2500 m (un poco arriba del nivel promedio de congelamiento) que tiene la mejor correlación (50%) con precipitación. Falvey and Garreaud 2007

Precipitación en latitudes medias Garreaud 2007

(a)  (P,U 850 ) Anual (a)  (T 2m,U 850 ) Anual prescribed SST influences SAT a. r(U850,P) b. r(U850,SAT) Wind-precipitation and Wind-SAT covariability at annual timescale (year-to-year)

Precipitacion en Latitudes medias Modest annual cycle in the extratropics