Teleconnection Patterns and Seasonal Climate Prediction over South America The Final Chapter???

transcript

Teleconnection Patterns and

Seasonal Climate Prediction over

South America

The Final Chapter???

Tércio Ambrizzi and Rosmeri P. da Rocha

University of São Paulo, São Paulo, Brazil

EUROBRISA 2010 – Barcelona, Spain

OBJECTIVE

To analyze in detail 21 years of ECWMF seasonal forecast simulations using basic statistical methods and particularly the linear wave theory, in order to evaluate the seasonal forecast skill and its useful value

(Dawson et al 2010 – CD)

(1/3º x 1/3º and 0,83º lat x 1,25º lon)

(1º x 1º and 1,25º lat x 1,825º lon)

DATA AND METHODOLOGY• Climatological Data used : ECMWF/ERA40 – period 1982 – 2001

• ECMWF Coupled GCM – Hindcast Period – 1982 – 2001 – 11 ensemble members – 6 months forecasting

• The seasons are: DJF (Summer), MAM (Fall), JJA (Winter), and SON (Spring)

• To create the seasonal datasets it was used the third month of each six months forecasting (PREV3) and three months seasonal forecasting (3MES)

• Pearson linear correlation was used in some of the analyzes

•The basic variables used in this presentation is Zonal (U) and Meridional Wind (V)

• Ray tracing analysis will be presented as well

3MESAutum

Winter

Spring

Summer

Simbol Regions Latitude Longitude

RS South 25º-35ºS 60º-50ºW

SD Southeast 15º-25ºS 55º-65ºW

CO Centre West 5º-15ºS 60º-50ºW

ND Northeast 2.5º-12.5ºS 45º-35ºW

REGIONS WHERE THE MODEL WILL BE VALIDATED CONSIDERING THE 3MES AND PREV3

Zonal and Meridional Seasonal Wind at 200 hPa for ERA 40 and 3MES inside the previous four regions

Model superstimatethe zonal wind and understimate the meridional wind

U (850 hPa) V (850 hPa)

U (200 hPa) V (200 hPa)

TOTAL AMPLITUDE OF U AND V WIND FOR EACH ENSEMBLE MEMBER AND EACH FORECASTING MONTH (RS BOX)

ZONAL AND MERIDIONAL WIND ERRORS FOR THE SUMMER

ZONAL WIND MERIDIONAL WIND

ZONAL AND MERIDIONAL WIND ERRORS FOR WINTERZONAL WIND MERIDIONAL WIND

ZONAL WINDA COMPOSITES FOR DJF AND JJA (200 hPa – m/s)

DJF JJA

ZONAL WIND CROSS SECTION AT 30o AND 50oS FOR 3MES AND DJF - JJA (m/s)

DJF JJA

LATITUDINAL MEAN SEASONAL ZONAL WIND at 200 hPa - (m/s)

ZONAL WIND ERRORS PREV3/3MES – ERA40

DJF JJA

STATIONARY WAVENUMBER (Ks) - DJF ERA40

Ks Meridional cross section

STATIONARY WAVENUMBER (Ks) - JJA ERA40

Ks Meridional cross section

SEASONAL RAY TRACING ANALYSIS FOR WAVE NUMBERS=2 and 3 (WN=2-3) (ERA40 AND ALL 11 MEMBERS)

WN2 WN3

PRECIPITATION MODEL’S BEHAVIOUR

SUMMER PRECIPITATION COMPARISON BETWEEN CMAP AND ERA40

ERA40 - CMAP

WINTER PRECIPITATION COMPARISON BETWEEN CMAP AND ERA40

ERA40 - CMAP

SEASONAL ZONAL MEAN PRECIPITATION (mm/day)

MODELCMAP

SEASONAL PRECIPITATION COMPARISON BETWEEN CMAP AND MODEL FOR THE NORTHEAST BRAZIL“ND”

ModelCMAP

El Niño years

SEASONAL PRECIPITATION ANOMALIES IN THE NORTHEAST BRAZIL BOX (ND) – ALL ENSEMBLE MEMBERS

SEASONAL PRECIPITATION COMPARISON BETWEEN CMAP AND MODEL AND SEASONAL PRECIPITATION ANOMALIES IN THE CENTER WEST BRAZILIAN BOX (CO) – ALL ENSEMBLE MEMBERS

SEASONAL PRECIPITATION COMPARISON BETWEEN CMAP AND MODEL AND SEASONAL PRECIPITATION ANOMALIES IN THE SOUTHEAST BOX (SD) – ALL ENSEMBLE MEMBERS

SEASONAL PRECIPITATION COMPARISON BETWEEN CMAP AND MODEL AND SEASONAL PRECIPITATION ANOMALIES IN THE SOUTH BOX (RS) – ALL ENSEMBLE MEMBERS

El Niño

summary

• The GCM is not able to correctly represent the position of the maximum and minimum hemispheric zonal wind (large variability among the ensemble members)

• There are considerable errors in the amplitudes of the zonal and meridional wind over different regions of South America.

• The precipitation is overestimated in the hemispheric analysis but the model underestimate it in the different regions over South America.

• Ray tracing analyzes clearly suggest that the model is not able reproduce the expected wave trajectory because it does not represent the Southern Hemisphere zonal wind variability. Bigger wavenumber larger variability among the trajectories.

IS THIS THE END??

FUTURE WORK

• Repeat all previous analyzes for the Meteo Office and CPTEC hindcast data.

• Select some specific years to analyze the atmospheric circulation over South America in order to determine some dynamical aspects of the model ensemble members and their deviation. We have to look more careful at ENSO years

• A Scientific paper is underway containing the main results of the first part of this work

• One M.Sc. Dissertation was concluded and the work was presented in some international conferences.

GRUPO DE ESTUDOS CLIMÁTICOS

THANK YOU FOR YOUR ATTENTION THANK YOU FOR YOUR ATTENTION AND TO EUROBRISA FOR THE OPPORTUNITYAND TO EUROBRISA FOR THE OPPORTUNITY

TO WORK IN THIS PROJECTTO WORK IN THIS PROJECT

CLIMATE STUDIES GROUP

Teleconnection Patterns and Seasonal Climate Prediction over South America The Final Chapter???

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