CORRECTION OF CPTEC/INPE AGCM PRECIPITATION ERRORS IN SEASONAL

SIMULATIONS

Iracema F.A.CavalcantiSilvia M.B. Araujo

CPTEC/INPEBrazil

Climatological features

NNE : MAM

Rainy season

NSE: DJF

ITCZ

SACZ

OBJECTIVE: To remove anomaly precipitation errors of two regions of South America aiming the improvement of the seasonal

prediction.

• DATA AND METHOD:

• Observed precipitation CMAP and GPCP

• Model Simulation: CPTEC/INPE AGCM T62L28

• Period: 1981-2000

• NNE region (10,2ºS - 2,7ºS; 39.3W- 35.6W) MAM

• NSE region (21,4ºS - 15,8ºS; 43,1ºW - 35,6ºW;) DJF

• The errors were calculated by the differences between model and observed mean precipitation in each region and each year.

• The errors were classified in crescent order and divided in groups

ERRORS in NNE

Large positive errors 1.26Small Positive errors 0.12Large negative errors -1.49Small negative errors -0.44

NNE

2.030.31-1.26-0.34

NSE

PRECIPITATION ANOMALIES OBSERVED, SIMULATED, CORRECTED MAM NNE

Anomalias Observadas, do Modelo e Corrigidas - NNE (MAM)

-4-3

-2-1

01

23

45

1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

Anos

Ano

mal

ias

Anol. Obs.Anol. Mod.Anol. Corr.

PRECIPITATION ANOMALIES OBSERVED, SIMULATED, CORRECTED DJF NSE

Anomalias Observadas, do Modelo e Corrigidas - NSE (DJF)

-4

-3

-2

-1

0

1

2

3

4

5

1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000Anos

Ano

mal

ias

Anol. Obs.Anol. Mod.Anol. Corr.

Ocean and Atmospheric features

• G1: Large negative anomaly errors• G2: Small negative anomaly errors• G3: Small positive anomaly errors• G4: Large positive anomaly errors

• 3 extreme years of each group

Precipitation anomalies G1 G4

GPCP

AGCM

Precipitation anomalies G2 G3

SST anomalies

G2

G4

G1

G3

OLR observed anomalies

AGCM OLR anomalies

G1 G4

OLR observed anomalies

AGCM OLR anomalies

G2 G3

G1 G4

ERAI

AGCM

850 hPa

G2 G3

ERAI

AGCM

850 hPa

NORTHERN SOUTHEAST

Precipitation anomalies

AGCM

G1 G4

GPCP

AGCM

Precipitation anomaliesG2 G3

GPCP

SST anomalies G1 G4

G2 G3

Observed OLR anomalies

AGCM OLR anomalies

G1 G4

Observed OLR anomalies

AGCM OLR anomalies

G2 G3

G1 G4

ERAI

AGCM

G2 G3

ERAI

AGCM

Conclusion• NNE (MAM) : Large errors when there is MJO signal Apply G1 correction when there is less convection in Indonesia region.Apply G4 correction when there is more convection in Indonesia region.

• NSE (DJF) : Large errors in ENSO

Apply the G1 correction for El Niño and G4 correction for La Niña

• Both cases: errors are related to the Low level flow

NEXT

• Apply the correction to the past seasonal prediction for verification and further use.

• Correction of each grid point .

• Analyses of other areas of South America

Meira and Cavalcanti, 2009

Meira and Cavalcanti, 2009