Towards the prediction of the East Africa short rains based on sea-surface temperature–atmosphere coupling

Mutai, Charles; Ward, Martin; Colman, Andrew

doi:10.1002/(sici)1097-0088(199807)18:9<975::aid-joc259>3.0.co;2-u

Cited by 171 publications

(151 citation statements)

References 58 publications

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“…Inter-annual variability of seasonal rains results from complex interactions of forced and free atmospheric variations. Mutai et al (1998) observed that OND variability is stronger than MAM while Phillips and McIntyre (2000) observed that the low interannual variability of MAM rainfall can be attributed to its insignificant relationship with ENSO. The ENSO is the most dominant perturbation responsible for inter-annual climate variability, especially OND over eastern and southern Africa.…”

Section: Trend Analysis Of Annual and Seasonal Rainfallmentioning

confidence: 99%

Determination of seasonal rainfall variability, onset and cessation in semi-arid Tharaka district, Kenya

Recha

Makokha

Traoré

et al. 2011

Theor Appl Climatol

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The study quantified rainfall variability for March-May (MAM) and October-December (OND) seasons in Tharaka district, Kenya. The parameters analysed were inter-annual variability of seasonal rainfall, onset and cessation using daily rainfall data in three agro-ecological zones' stations. Percentage mean cumulative method was used to determine onset and cessation, and seasonal variability was estimated using rainfall variability indices. Although both seasons are highly variable, OND has been persistently below mean over time while MAM shows high within-season variability. Despite the near uniformity in the mean onset and cessation dates, the former is highly variable on an inter-annual scale. The two rainfall seasons are inherently dissimilar and therefore require specific cropping in agro-ecological zone LM4 and LM4-5. It is possible that farmers in IL5 are missing an opportunity by under-utilising MAM rainfall. The results should be incorporated in implications of climate variability and vulnerability assessment in semi-arid Tharaka district.

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Section: Trend Analysis Of Annual and Seasonal Rainfallmentioning

confidence: 99%

Determination of seasonal rainfall variability, onset and cessation in semi-arid Tharaka district, Kenya

Recha

Makokha

Traoré

et al. 2011

Theor Appl Climatol

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“…During the warm ENSO events, the evaporation rate is high, leading to increased moisture in the atmosphere and the resultant heavy rainfall. The cold ENSO events react in the opposite manner (Mutai et al 1998;Glantz 2001;Schreck and Semazzi 2004). However, ENSO explains about 50 % of the rainfall variability over Eastern Africa, with other factors responsible for the variance (Ogallo 1988;Nicholson and Nyenzi 1990;Nicholson 1996;Mutai et al 1998;Indeje et al 2000).…”

Section: Introductionmentioning

confidence: 87%

“…Dry and cold air masses (Siberian anticyclones) from the Arabian Sea are pushed by winter monsoon over Lake Victoria to yield some humidity, which gives a little rainfall in the highlands from December to February (Mutai et al 1998;Indeje et al 2000;Mutai and Ward 2000;Clark et al 2003;Ilunga et al 2004;Anyah and Semazzi 2007;Ilunga et al 2008;Kizza et al 2009). Thus, the sea-surface temperatures-signals ENSO phenomenon over the Atlantic, Indian and Pacific oceans contribute significantly to the seasonal rainfall variability over Rwanda (Indeje et al 2000;Schreck and Semazzi 2004;Washington and Preston 2006;Anyah and Semazzi 2007;Shongwe et al 2011).…”

Section: Study Areamentioning

confidence: 96%

“…The subtropical zones, especially sub-Saharan Africa (SSA), have become more arid (Niasse et al 2004;Druyan et al 2008;Eriksen et al 2008;Claudia et al 2010). East Africa experiences the dipole rainfall pattern that is characterized by increases over the northern region and decreases over the eastern and southern regions (Mutai et al 1998;Mutai and Ward 2000;Schreck and Semazzi 2004;Anyah and Semazzi 2007;Eriksen et al 2008;Ilunga and Muhire 2010), with Rwanda becoming wetter over the northern highlands and south-western region and warmer over the eastern lowlands and the central plateau (Muhire and Ahmed 2014).…”

Section: Introductionmentioning

confidence: 99%

“…It is established that there is a strong relationship between the short rains (October-December) over East Africa and SST patterns in the tropical Pacific, tropical Indian and, to a lesser extent, tropical Atlantic Oceans (Beltrando and Camberlin 1993;Rowell et al 1994;Mutai et al 1998;Schreck and Semazzi 2004;Anyah and Semazzi 2007;Shyongwe et al 2009Shyongwe et al , 2011. This positive correlation results from the influence of global and regional large-scale sea-surface temperature-forced signals ENSO phenomenon on the tropical atmospheric circulation (Rasmusson and Carpenter 1982;Ropelewski and Halpert 1987;Rowell et al 1994;Mutai and Ward 2000;Schreck and Semazzi 2004).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Relationships between Rwandan seasonal rainfall anomalies and ENSO events

Muhire

Ahmed

Abutaleb

2014

Theor Appl Climatol

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This study aims primarily at investigating the relationships between Rwandan seasonal rainfall anomalies and El Niño-South Oscillation phenomenon (ENSO) events. The study is useful for early warning of negative effects associated with extreme rainfall anomalies across the country. It covers the period 1935-1992, using long and short rains data from 28 weather stations in Rwanda and ENSO events resourced from Glantz (2001). The mean standardized anomaly indices were calculated to investigate their associations with ENSO events. One-way analysis of variance was applied on the mean standardized anomaly index values per ENSO event to explore the spatial correlation of rainfall anomalies per ENSO event. A geographical information system was used to present spatially the variations in mean standardized anomaly indices per ENSO event. The results showed approximately three climatic periods, namely, dry period , semi-humid period (1961)(1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976) and wet period (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992). Though positive and negative correlations were detected between extreme short rains anomalies and El Niño events, La Niña events were mostly linked to negative rainfall anomalies while El Niño events were associated with positive rainfall anomalies. The occurrence of El Niño and La Niña in the same year does not show any clear association with rainfall anomalies. However, the phenomenon was more linked with positive long rains anomalies and negative short rains anomalies. The normal years were largely linked with negative long rains anomalies and positive short rains anomalies, which is a pointer to the influence of other factors other than ENSO events. This makes projection of seasonal rainfall anomalies in the country by merely predicting ENSO events difficult.

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ENSO signals in East African rainfall seasons

2000

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The evolutions of ENSO modes in the seasonal rainfall patterns over East Africa are examined in this study. The study covers the period 1961–1990. Both rotated empirical orthogonal function (EOF) and simple correlation analyses were used to delineate a network of 136 stations over East Africa into homogeneous rainfall regions in order to derive rainfall indices. Time series generated from the delineated regions were later used in the rainfall/ENSO analyses. Such analyses involved the development of composite rainfall map patterns for El Niño and post‐ENSO (+1) years in order to investigate the associations between seasonal evolution of El Niño–Southern Oscillation (ENSO) signals and the space‐time evolution of rainfall anomalies over the region. Analyses based on both EOF and simple correlation techniques yielded eight homogeneous rainfall regions over East Africa. The results showed unique seasonal evolution patterns in rainfall during the different phases of the ENSO cycles. East African rainfall performance characteristics were stratified to identify distinct rainfall anomaly patterns associated with ENSO and post‐ENSO (+1) years. These can be applied in conjunction with skilful long lead (up to 12 months) ENSO prediction to provide guidance on likely patterns of seasonal rainfall anomalies over the region. Such information can be crucial for early warning of socio‐economic disasters associated with extreme rainfall anomalies over East Africa. Copyright © 2000 Royal Meteorological Society

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Towards the prediction of the East Africa short rains based on sea-surface temperature–atmosphere coupling

Cited by 171 publications

References 58 publications

Determination of seasonal rainfall variability, onset and cessation in semi-arid Tharaka district, Kenya

Determination of seasonal rainfall variability, onset and cessation in semi-arid Tharaka district, Kenya

Relationships between Rwandan seasonal rainfall anomalies and ENSO events

ENSO signals in East African rainfall seasons

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