Analysis of Daily Rainfall from a Nested Modeling System for South America Anji Seth International Research Institute for Climate Prediction Maisa Rojas,

Analysis of Daily Rainfall from a Nested Modeling System for

South America

Anji SethInternational Research Institute for Climate Prediction

Maisa Rojas, University of ChileBrant Liebmann, NOAA CDC

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Outline• Climatology of daily rainfall (V. Kousky, CPC)• Spatial Characteristics

• Observed Daily Rainfall: FMAM 1983, 1985• Simulated Daily Rainfall: FMAM 1983, 1985

• Temporal characteristics• Observed Daily Rainfall: FMAM 1983, 1985• Simulated Daily Rainfall: FMAM 1983, 1985

• Sensitivity: Local Forcing,Domain Effects• Preliminary Conclusions

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

•V. Kousky, CPC

•Climatology (1979-1995) Computed for Brazil

•Typical station coverage

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Annual RainfallFrequency (>1mm)

% days/year

V. Kousky, CPC

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Frequency (>1mm)% days/month

V. Kousky, CPC

•Central and Southeast:>85% (summer)<25% (winter)

•Northwest:>75% year round

•Northeast:>65% (jan-may)<15% (jun-dec)

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Frequency (>10 mm)% days/month

Peak frequencies in The northwest drop to 50%

V. Kousky, CPC

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Frequency (>25 mm)% days/month

Peak frequencies in The northwest drop to 10% (summer months)

Southern Brazil has Heavy rainfall events year round

V. Kousky, CPC

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Station Coverage for Observed Daily RainfallB. Liebmann, CDC

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Rainfall Frequency (>1 mm) % days/JFMAM

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Rainfall Frequency (>10 mm) % days/JFMAM

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Rainfall Frequency (>25 mm) % days/JFMAM

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

RegCM2 (Giorgi et al., 1993)

• 110x145x14• 60 km resolution• Remote:

Reanalyses 83,85 CCM3(x3) 83,85

• Local: deforestation

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Observed

RegCM

Frequency>1 mm

19851983

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Observed

RegCM

Frequency>10 mm

19851983

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Observed

RegCM

Frequency>25 mm

19851983

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Observed Daily Rainfall, 1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Observed Rainfall Frequency 1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Simulated, Observed Daily Rainfall

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Simulated, Observed Daily Rainfall

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Simulated*, Observed Daily Rainfall

1983 1985

*GCM>RegCM

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Simulated*, Observed Daily Rainfall

1983 1985

*GCM>RegCM

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

ST/RR/GR1/GR2/GR3Observed, Simulated Rainfall Frequency

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

ST/RR/GR1/GR2/GR3Observed, Simulated Rainfall Frequency

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

ST/RR/GR1/GR2/GR3Observed, Simulated Rainfall Frequency

1983 1985

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Preliminary Conclusions• Spatial Characteristics – using thresholds of 1,10,and 25 mm

• Observed Daily Rainfall frequencies were notable higher in 1985 than 1983 in Nordeste and the Amazon.• Simulated Daily Rainfall reproduced the observed patterns in the two years remarkably well.

• Temporal characteristics – time series and frequency distributions showed

• Observed Daily Rainfall was deficient throughout the 1983 season in Nordeste and early in the season in the Amazon.• Simulated Daily Rainfall captured the observed frequency distributions well in the reanalyses> RegCM

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003

Workshop on Theory and Use of Regional Climate Models ICTP, Trieste June 2003