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Climate “Sensitivity” and Impact on Agriculture In The Sahel

Abdoulaye SARR AIACC- AF20 Johannesburg S.A March 10-14, 2003

Problem? Climate Circulation Anomalies Long and Frequent dry spells Critical Agricultural Campain Below normal rainfall Negative Impact on Production

Socio-economic Consequences

AREA

Climate Caracteristics Long drought 1968- 1987

Improvement Since 1988 - With irregular occurrence of

dry years- High Spatial Variability

Review of Documented Dynamical Factors Influencing Rainfall in Sahel:

Anomalous warm SST in the tropical atlantic anomalous atmospheric circulation in the

tropics Most consistently demonstrated difference

between wet and dry years in the Sahel is the strength of the AEJ and its location in latitude (Farther N in Wet Years).

The TEJ may also play an important role :dry years (weak TEJ), Wet years (strong TEJ).

Authors among Many others

( Kidson 1977; Tanaka 1975; Kanamitsu and

Krishnamurti 1978; Lamb, 1978 a,b;Nevell and Kidson 1979, 1984; Dennet 1985; Folland 1986; Fontaine and Janicot 1992; Fontaine 1995, Jenkins, 1998; Grist and

Nicholson, 2001)

Application to the dry Summer Season 2002 over Sahel

SLP anomaly for July 2001 (above)

and (2002) below.

Geopotential height anomaly (gpm) at 850 for July 2001 (above) and 2002

(below).

Skt anomalies July 2002

Mean position AEJ wet and dry years

Mean zonal wind at 700 hPa July 2002

Rainrate anomaly for 2001 (above) and 2002 (below)

June 2002 Precip

July 2002 Precip (1dg GPCC)

August 2002 Precip

September 2002 Precip

October 2002 Precip

Precip Percentage of Normal (1961-1990) July 2002

Precipitation precentage of Normal (1961-1990) for August 2002

Impact on Agriculture

GNP (Intercomparison)

1 000 000

1 200 000

300 000

0 500 000 1 000 000 1 500 000

1

2

3

Yea

rs

Production (T)

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Ground-nut Production For 2000 (1), 2001 (2) and 2002(3)