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Southern South Southern South American climate trendsAmerican climate trends
Inés Camilloni – Moira DoyleInés Camilloni – Moira DoyleUniversity of Buenos AiresUniversity of Buenos Aires
Second AIACC Regional Workshop for Latin America and the Caribbean
Buenos Aires, 24-27 August 2004
AIACC Project LA26: Impact of Global Change on the Coastal Areas of the Río de la Plata: Sea Level Rise and
Meteorological Effects
OutlineOutline
TemperatureTemperature
RainfallRainfall
River dischargesRiver discharges
Surface circulationSurface circulation
Global annual temperature trends: Global annual temperature trends: 1976-20001976-2000
IPCC (2001)
Annual temperature trends in SE South Annual temperature trends in SE South AmericaAmerica
efecto urbano filtrado
Global annual rainfall trends: 1900-Global annual rainfall trends: 1900-20002000
IPCC (2001)
SE South America: 23%Chile: 50%
Annual rainfall trends (mm/year): 1960-Annual rainfall trends (mm/year): 1960-20002000
- 70 - 65 - 60 - 55 - 50 - 45 - 40
Tendencia AN UAL - O C -SE (Sum a Pesados)
- 40
- 35
- 30
- 25
- 20
The region shows increments in the annual rainfall between 10% and 40%.
The increments in some regions of the Río de la Plata basin are between 200 and 300 mm in 40 years.
IMPACTS
Impact of rainfall trends: Impact of rainfall trends: displacement of the agricultural displacement of the agricultural
border border
- 7 5 - 7 0 - 6 5 - 6 0 - 5 5
- 5 5
- 5 0
- 4 5
- 4 0
- 3 5
- 3 0
- 2 5
- 2 0
1950-691980-99 The agricultural
border moved to the west.
Annual rainfall (mm)
Impact of rainfall trends: changes in river Impact of rainfall trends: changes in river dischargesdischarges
Río de la Plata basinRío de la Plata basin
Paraguay RiverParaná River
Uruguay RiverSalado River
Impact of rainfall trends: changes in river Impact of rainfall trends: changes in river dischargesdischarges
Río de la Plata basinRío de la Plata basin
Paraná River - Corrientes
annu
al d
isch
arge
(m
3 /s)
0
5000
10000
15000
20000
25000
30000
35000
40000
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Uruguay River- Paso de los Libres
annu
al d
isch
arge
(m3 /s
)
0
2000
4000
6000
8000
10000
12000
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Salado River - RP 70
annu
al d
isch
arge
(m3 /s
)
0
100
200
300
400
500
600
700
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Paraguay River - Puerto Bermejo
annu
al d
isch
arge
(m
3 /s)
0
2000
4000
6000
8000
10000
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Are Are streamflow streamflow
trendstrends really related really related
toto precipitation trendsprecipitation trends
or due toor due to land use land use
change?change?
Berbery and Barros (2002)
There is an amplification of the rainfall signal in the river flow that cannot be completely attributed to land use/cover changes.
Averaged rainfall rates and river discharge for the Río de la Plata Basin for different timescale
variability
Trends in extreme rainfall eventsTrends in extreme rainfall events
Number of rainfall events larger than 100 mm in 2 days in central-east Argentina.
Annual frequency of extreme rainfall Annual frequency of extreme rainfall eventsevents
Annual frequencies of rainfall events larger than 150 mm in 2 days for 1991/2002.
Changes in the annual frequency of Changes in the annual frequency of extreme rainfall eventsextreme rainfall events
Difference of annual frequencies of rainfall events larger than 150 mm in 2 days between 1959/1968 and 1991/2002.
% of rainfall due to Mesoscale Convective % of rainfall due to Mesoscale Convective ComplexesComplexes
From Zipser
Changes in extreme monthly Changes in extreme monthly dischargesdischarges
Decadal number of cases with monthly discharge anomalieslarger than 2 standard deviations
Paraná River - Corrientes
21 1
01 1
0
12
10
0
2
4
6
8
10
12
14
1910-19 1920-29 1930-39 1940-49 1950-59 1960-69 1970-79 1980-89 1990-99
Uruguay River - Paso de los Libres
5 5 54
34
5
7
10
0
2
4
6
8
10
12
14
1910-19 1920-29 1930-39 1940-49 1950-59 1960-69 1970-79 1980-89 1990-99
Changes in extreme monthly Changes in extreme monthly dischargesdischarges
Decadal number of cases with monthly discharge anomalieslarger than 2 standard deviations
Rainfall trends in ChileRainfall trends in Chile
La Serena
Puerto Montt
29.5°S 71.1°W
41.4°S 73.05°W
IMPACTS
Atuel River - La Angostura
annu
al d
isch
arge
(m
3 /s)
0
20
40
60
80
100
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
San Juan River - Km 47.3
annu
al d
isch
arge
(m
3 /s)
0
50
100
150
200
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Neuquén River - Paso de Indios
annu
al d
isch
arge
(m
3 /s)
0
100
200
300
400
500
600
700
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Colorado River - Pichi Mahuida
annu
al d
isch
arge
(m
3 /s)
0
100
200
300
400
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Impact of rainfall trends: changes in river Impact of rainfall trends: changes in river dischargesdischarges
Cuyo and Comahue regionsCuyo and Comahue regions
-75 -70 -65 -60 -55 -50 -45-55
-50
-45
-40
-35
-30
-25
-20
Changes in surface circulationChanges in surface circulation
1951-1960 1991-2000
AA
- 6 5 - 6 0 - 5 5 - 5 0 - 4 5
- 4 5
- 4 0
- 3 5
- 3 0
- 2 5
- 2 0
- 6 5 - 6 0 - 5 5 - 5 0 - 4 5
- 4 5
- 4 0
- 3 5
- 3 0
- 2 5
- 2 0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
FL1 FL2 Lineal (FL1) Lineal (FL2)
PC1 PC2
Monthly SLP patterns over South Monthly SLP patterns over South AmericaAmerica
Southward shift of the western border of the South Atlantic High since 1950.
RRío de la Plata River mean level ío de la Plata River mean level (mm)(mm)
600
650
700
750
800
850
900
950
1000
1050
1900 1920 1940 1960 1980 2000 2020
Buenos Aires: 1.7 0.1 mm/year
D’Onofrio (2002)
Decadal distribution of Decadal distribution of “sudestadas” in the Río de la Plata“sudestadas” in the Río de la Plata
Escobar et al (2004)
Concluding remarks: observed changes Concluding remarks: observed changes (1)(1)
► Precipitation in Southeastern South America shows important positive trends during the last four decades
with increases of up to 40% in some regions of northeastern Argentina
As a consequence, the agricultural border moved to the west
River discharges in the Río de la Plata basin increased as a result of the positive precipitation trends in northeastern Argentina, southern Brazil and Paraguay
Concluding remarks: observed changes Concluding remarks: observed changes (2)(2)
The increase of extreme rainfall events in northeastern Argentina is important with a large number of damages
River discharges in Cuyo, Comahue and Patagonia show negative trends: impacts on regional and national economies Displacement to the south of the western border of the South Atlantic High
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