Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

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Alice M. Grimm Alice M. Grimm Marcia T. Zilli Marcia T. Zilli Federal University Federal University of Paraná, Curitiba, Paraná, Brazil of Paraná, Curitiba, Paraná, Brazil [email protected] [email protected] Jeremy Pal and Filippo Giorgi Jeremy Pal and Filippo Giorgi The Abdus Salam International Centre for Theoretical Physics, The Abdus Salam International Centre for Theoretical Physics, Trieste - Italy Trieste - Italy

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CONNECTION BETWEEN EARLY AND PEAK SUMMER MONSOON PRECIPITATION IN SOUTH AMERICA. Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil [email protected] Jeremy Pal and Filippo Giorgi - PowerPoint PPT Presentation

Transcript of Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

Page 1: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

Alice M. GrimmAlice M. Grimm

Marcia T. ZilliMarcia T. Zilli

Federal UniversityFederal University of Paraná, Curitiba, Paraná, Brazilof Paraná, Curitiba, Paraná, [email protected]@fisica.ufpr.br

Jeremy Pal and Filippo GiorgiJeremy Pal and Filippo Giorgi

The Abdus Salam International Centre for Theoretical Physics, Trieste - ItalyThe Abdus Salam International Centre for Theoretical Physics, Trieste - Italy

Page 2: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

MOTIVATION

Summer is the rainy season in most of the SA continent. The Summer is the rainy season in most of the SA continent. The quality of the monsoon is important for agriculture, hydroelectric quality of the monsoon is important for agriculture, hydroelectric power generation, and water management. Very densely populated power generation, and water management. Very densely populated areas are severely affected by oscillations in the South Atlantic areas are severely affected by oscillations in the South Atlantic Convergence Zone (SACZ), whose enhancement frequently causes Convergence Zone (SACZ), whose enhancement frequently causes urban floods and landslides. It is therefore important to understand urban floods and landslides. It is therefore important to understand the mechanisms responsible for the variability of the South American the mechanisms responsible for the variability of the South American Monsoon (SAM) in order to improve the ability to predict it. Monsoon (SAM) in order to improve the ability to predict it.

The ENSO impact shows strong regional differences and strong The ENSO impact shows strong regional differences and strong changes within the monsoon season, from spring to peak summer, changes within the monsoon season, from spring to peak summer, suggesting a relationship between late spring and peak summer, with suggesting a relationship between late spring and peak summer, with an important role of regional processes during the peak monsoon. A an important role of regional processes during the peak monsoon. A surface-atmosphere interaction hypothesis involving soil moisture in surface-atmosphere interaction hypothesis involving soil moisture in spring has been proposed to explain this relationship, with a role for spring has been proposed to explain this relationship, with a role for the highlands in Southeast Brazil (Grimm 2003, 2004). the highlands in Southeast Brazil (Grimm 2003, 2004).

Page 3: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

MOTIVATIONFigura 1. Áreas de Característica Operativa (ROC) para as previsões de precipitação de DJF baixo do normal com um mês de antecedência, para o período 1981-2001. A previsão de multi-modelos se baseia em ponderar igualmente as previsões probabilísticas de 3 categorias de 8 CGCMs (painéis superiores) y 3 AGCMs forçados por TSMs prognosticadas (painel inferior). A curva ROC demarca o equilibrio entre eventos “exitosos” e “falsos alarmes” para prognósticos com níveis de probabilidade variável. A falta de discriminação (taxa de éxitos=taxa de falsos alarmes) indica falta de desempenho do modelo, gerando áreas ROC de 0.5. Valores de área ROC menores que 0.5 indicam desempenho negativo e os valores maiores, desempenho positivo, com valor máximo 1.0. A região Centro-leste do Brasil está marcada no último painel inferior direito (Cavalcanti et al. 2006).

Page 4: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

OBJECTIVESOBJECTIVES

To verify whether antecedent anomalous conditions in spring influence the summer monsoon not only in ENSO but also in non-ENSO years.

To observationally verify possible links between rainfall in spring and temperature in late spring, as well as between temperature in late spring and rainfall in the peak monsoon season.

To verify the impact of the relationships between spring and summer rainfall on river streamflows.

To investigate the possible role of soil moisture, SST and topography through sensitivity experiments with a regional model.

Page 5: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

ENSO-related variationsEl Niño La Niña El Niño - moisture flux

(Grimm, 2003; 2004)

Nov

Jan

Similar intraseasonal changes are present in other years as well… Similar intraseasonal changes are present in other years as well…

Page 6: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

SPRING EOFs

EOF1 - 18.5 %

1960 1970 1980 1990 2000

-3

-2

-1

0

1

2

Fa

cto

r S

co

res

do

Pri

me

iro

Mo

do

TEMPO

1960 1970 1980 1990 2000

-3

-2

-1

0

1

2

Fa

cto

r S

co

res

do

Se

gu

nd

o M

od

o

TEMPO

EOF2 - 16.7 %

Grimm and Zilli 2007

Page 7: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

SUMMER EOFs

EOF1 - 22.0 %

EOF2 - 10.1 %

1960 1970 1980 1990 2000

-3

-2

-1

0

1

2

3

Fa

cto

r S

co

res

do

Pri

me

iro

Mo

do

TEMPO

1960 1965 1970 1975 1980 1985 1990 1995 2000

-2

-1

0

1

2

3

Fa

cto

r S

co

res

do

Se

gu

nd

o M

od

o

TEMPO

Grimm and Zilli 2007

Page 8: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

RESULTS – NOVEMBER AND JANUARY REOFs

NovemberREOF1 - 14.6 %

JanuaryREOF1 - 23.4 %

1960 1970 1980 1990 2000

-1,5

-1,0

-0,5

0,0

0,5

1,0

1,5

2,0

2,5

Fa

cto

r S

co

res

Ro

tac

ion

ad

o d

o P

rim

eir

o M

od

o

TEMPO

1960 1970 1980 1990 2000

-3

-2

-1

0

1

2

3

Fa

cto

r S

co

res

Ro

tac

ion

ad

o d

o P

rim

eir

o M

od

o

TEMPO

Grimm and Zilli 2007

Page 9: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

CORRELATION BETWEEN SPRING AND SUMMER PCs

Spring

Summer

EOF1

EOF1

r=0.24

EOF1

EOF2

r=-0.31

EOF2

EOF1

r=0.29

November

January

REOF1

REOF1

r=-0.32

Grimm and Zilli 2007

Page 10: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

HYPOTHESIS

Spring dry conditions in central-east Brazil

Less soil moisture /Higher surface temperature in late spring

Lower surface pressure / more convergence /Enhanced convection over the highlands in southeast

Brazil

Moisture flux / convergence into central-east Brazil

Cyclonic circulation anomaly over southeast Brazil

Peak summer wet conditions in central-east Brazil

More net surface solar radiation and higher SST off southeast Brazil coast in late spring

Diagram of the pathway through which spring anomalous dry conditions may lead to subsequent peak summer wet conditions in central-east Brazil. The above diagram is also

valid for opposite anomalies, starting from spring wet conditions in central-east Brazil.

Page 11: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

SCHEMATIC DIAGRAM OF SPRING-SUMMER INVERSE RELATIONSHIP

Schematic evolution from (a) spring dry conditions to (b) peak summer wet conditions in Central-east Brazil, through decreasing low-level pressure,

convergence and cyclonic anomaly over southeast Brazil.(Grimm, Pal, and Giorgi 2007)

Page 12: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

TEMPERATURE-PRECIPITATION RELATIONSHIPS

19602000

Periods Allyears(40)

NonENSOyears(21)

ENSOyears(19)

P1 P1 10-20S40-48W

N J -0.30 -0.34 -0.26

ON DJ -0.34 -0.09 -0.51

ND JF -0.33 -0.45 -0.17

P2 P210-22S40-48W

N J -0.29 -0.25 -0.33

ON DJ -0.35 -0.11 -0.52

ND JF -0.35 -0.47 -0.22

P3 P310-20S40-50W

N J -0.29 -0.28 -0.29

ON DJ -0.32 -0.05 -0.50

ND JF -0.34 -0.43 -0.20

P4 P4 10-22S40-50W

N J -0.28 -0.20 -0.36

ON DJ -0.33 -0.08 -0.50

ND JF -0.36 -0.45 -0.24

Correlation between temperature in periods within spring and precipitation averaged over region P2 in following summer.

Correlation between precipitation in periods within spring and following summer.

Grimm, Pal and Giorgi (2007)

19602000

Periods Allyears(40)

NonENSOyears(21)

ENSOyears(19)

T1 P2 N J 0.26 0.19 0.33

ON DJ 0.15 -0.12 0.26

ND JF 0.14 0.07 0.19

T2 P2 N J 0.35 0.20 0.48

ON DJ 0.25 -0.08 0.39

ND JF 0.17 -0.04 0.31

T3 P2 N J 0.37 0.22 0.49

ON DJ 0.27 -0.06 0.41

ND JF 0.16 -0.06 0.31

Page 13: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

TEMPERATURE-PRECIPITATION RELATIONSHIPS

Negative significant correlation of October-November precipitation vs November surface air temperature averaged in 2º X 2º areas (Grimm, Pal

and Giorgi 2007).

Positive significant correlation of surface air temperature in November vs precipitation averaged in the bold rectangle in January (Grimm, Pal

and Giorgi 2007).

Page 14: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

15-DAY SLIDING MEAN PRECIPITATION

Composite evolution of the 30-day running mean precipitation (mm day-1), averaged over Central-East Brazil for all years (black line) and (left) for years in which spring (summer) PC1 is above 0.5 standard deviation (green (blue) line) or (right) for years in which spring (summer) PC1 is below -0.5 standard deviation (green (blue) line).

Spring EOF1 Summer EOF1

Page 15: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

RELATIONSHIPS BETWEEN JANUARY AND NOVEMBER STREAMFLOW

Example: Três Marias

Spring EOF1 Summer EOF1

Composite evolution of the 30-day running mean streamflow in Três Marias (left) for years in which spring (summer) PC1 is above 0.5 standard deviation (green (blue) line) or (right) for years in which spring (summer) PC1 is below -0.5 standard deviation (green (blue) line).

Page 16: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

MODELING STUDIES (Grimm, Pal and Giorgi 2007)

Response to 0.5 soil moisture in Central-East Brazil

Response to 1.5 soil moisture in Central-East Brazil

Page 17: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

MODELING STUDIES (Grimm, Pal and Giorgi 2007)

Response to reduced soil moisture + warmer SST

Realistic topography in eastern South America

Response to reduced topography in eastern S. America

Page 18: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

SCHEMATIC DIAGRAM OF SPRING-SUMMER INVERSE RELATIONSHIP

Schematic evolution from (a) spring dry conditions to (b) peak summer wet conditions in Central-east Brazil, through decreasing low-level pressure,

convergence and cyclonic anomaly over southeast Brazil.(Grimm, Pal, and Giorgi 2007)

Page 19: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

CONCLUSIONS

• There is an inverse relationship between precipitation in spring and There is an inverse relationship between precipitation in spring and summer in Central-East Brazil, provided that the precipitation anomalies summer in Central-East Brazil, provided that the precipitation anomalies during spring are strong enough. This relationship manifests itself in the during spring are strong enough. This relationship manifests itself in the connection between the first modes of precipitation variability in spring connection between the first modes of precipitation variability in spring and summer, as well as in the correlation analysis of precipitation in the and summer, as well as in the correlation analysis of precipitation in the two seasons. two seasons.

• Remote influences from SST anomalies are stronger in spring than in Remote influences from SST anomalies are stronger in spring than in summer. This lends support to the hypothesis that the reversal of summer. This lends support to the hypothesis that the reversal of anomalies in summer might be associated with regional processes of anomalies in summer might be associated with regional processes of surface-atmosphere interaction that are important during the monsoon surface-atmosphere interaction that are important during the monsoon season. season.

• The links in that hipothesis are supported by sensitivity experiments of a The links in that hipothesis are supported by sensitivity experiments of a regional model to soil moisture anomalies, to SST anomalies off the regional model to soil moisture anomalies, to SST anomalies off the southeast coast of Brazil and to topography in eastern South America.southeast coast of Brazil and to topography in eastern South America.

CRN 055

Page 20: Alice M. Grimm Marcia T. Zilli Federal University of Paraná, Curitiba, Paraná, Brazil

References

Grimm, A.M., J. Pal, and F. Giorgi, 2007: Connection between Spring Conditions and Peak Summer Monsoon Rainfall in South America: Role of Soil Moisture, Surface Temperature, and Topography in Eastern Brazil. Journal of Climate. In Press.

Grimm, A.M., 2003: The El Niño impact on the summer monsoon in Brazil: regional processes versus remote influences. J. Climate,16, 263–280.

Grimm, A.M., 2004: How do La Niña events disturb the summer monsoon system in Brazil? Climate Dynamics, 22, n. 2-3, 123-138.

Grimm, A.M., and M.T. Zilli, 2007: Interannual variability and seasonal evolution of Grimm, A.M., and M.T. Zilli, 2007: Interannual variability and seasonal evolution of summer monsoon rainfall in South America. summer monsoon rainfall in South America. In preparationIn preparation..