Table 1.
Significant Periodicities of Cases and Climate Indices.
| Spectrograms | |||
|---|---|---|---|
| Perioda 1 (time) | Period 2 (time) | Period 3 (time) | |
| Climate indices | |||
| ENSOb | 3.0–4.0 (1970–1975) | 3.5–5.0 (1982–1988) | 5.0–6.0 (1982–1998) |
| PDOc | 3.0–4.0 (1982–1985) | 4.0–6.0 (1985–2000) | 8.0–10.0 (1995) |
| Cases | |||
| Sahel | 1.0–2.0 (1972–1975) | 10.0–12.0 (1988–1991) | 5.0 (2002) |
| Central | 3.0–4.0 (1975–1982) | 3.0–3.5 (1995–1998) | 3.5–5.0 (1995–2005) |
| East | 5.0–6.5 (1978–1986) | 3.0–4.0 (1985–1988) | 4.0–5.0 (1986–1988) |
| Cases-ENSOd | |||
| Sahel | 1.0–4.5 (1972–1975) | 10.5–11.5 (1988–1995) | 5.0–6.0 (1995–2000) |
| Central | 3.5–5.0 (1975–1978) | 3.5–4.5 (1980–1988) | 3.0–4.0 (1995–2000) |
| East | 2.0–3.5 (1972–1975) | 4.0–6.0 (1978–1985) | 3.0–6.0 (1985–1988) |
| Cases-PDOe | |||
| Sahel | 10.0–11.0 (1988–1995) | 5.0–6.5 (1993–1995) | 5.0–7.0 (1995–2002) |
| Central | 3.5–4.0 (1975–1985) | 5.0 (1988–1992) | 3.0–4.5 (1995–2005) |
| East | 3.0–4.0 (1982–1988) | 4.0–7.0 (1984–1990) | 9.0 (1992–1994) |
aPeriodicities in years.
bEl Niño-Southern Oscillation.
cPacific Decadal Oscillation.
dCross wavelet spectra of cases and Indices of El Nino-Southern Oscillation.
eCross wavelet spectra of cases and Indices of Pacific Decadal Oscillation.