Cohérence intrasaisonnière de la variabilité pluviométrique interannuelle en Afrique du Sud

Richard, Yves; Camberlin, Pierre; Fauchereau, Nicolas; Mulenga, Henry

doi:10.3917/eg.311.0063

Cited by 8 publications

(5 citation statements)

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“…For example, in southern Africa prevailing suppression of photosynthesis in DJF and MAM El Niño events is at odds with SON enhancement, though the SON behavior will be shown to be a result of IOD interference in a following section. Furthermore, this corresponds with work by Richard et al (2002) that reported a seasonal shift between spring and summer rainfall in South Africa as being coupled to a main mode of precipitation variability, though not specifically attributed to ENSO-IOD interactions. Similarly, photosynthesis across West Africa switches from IOD suppression during MAM to enhancement during the rest of the year.…”

Section: Enso Associationsmentioning

confidence: 52%

ENSO and IOD teleconnections for African ecosystems: evidence of destructive interference between climate oscillations

Williams

Hanan

2011

Biogeosciences

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Abstract. Rainfall and vegetation across Africa are known to resonate with the coupled ocean-atmosphere phenomena of El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). However, the regional-scale implications of sea surface temperature variability for Africa's photosyntheis have received little focused attention, particularly in the case of IOD. Furthermore, studies exploring the interactive effects of ENSO and IOD when coincident are lacking. This analysis uses remotely sensed vegetation change plus a land surface model driven with observed meteorology to investigate how rainfall, vegetation, and photosynthesis across Africa respond to these climate oscillations. In addition to the relatively well-known ENSO forcing, the IOD induces large departures of photosynthesis across much of Africa associated with anomalies in rainfall and vegetation greenness. More importantly, sizeable independent effects can be suppressed or even reversed by destructive interferences during periods of simultaneous ENSO and IOD activity. For example, effects of positive IOD on southeastern Africa tended to dominate those of El Niño during their coincidence spanning 1997-1998, with sign reversal of El Niño's typically strong suppression of photosynthesis in this region. These findings call into question past analyses examining teleconnections to ENSO or IOD in isolation, and indicate the need to consider their simultaneous states when examining influences on hydroclimatic and ecological conditions across Africa.

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Section: Enso Associationsmentioning

confidence: 52%

ENSO and IOD teleconnections for African ecosystems: evidence of destructive interference between climate oscillations

Williams

Hanan

2011

Biogeosciences

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“…On the other hand, a strong variety of the rainfall regimes characterizes this part of the African continent. We note a very strong pressure gradient NW-NE [21], with a spatial coherence of the distribution of the precipitations. On the other hand, Congo presents a very low spatial coherence of the precipitations.…”

Section: Resultsmentioning

confidence: 74%

“…La zonalité climatique en Afrique australe est perturbée par l'opposition entre flux atlantique sec et flux humide de l'océan Indien. On note un gradient NW-NE très fort [21], avec une cohérence spatiale de la laise), qui concourent à la complexité de la répartition spatiale des jours sans pluie au niveau du Congo, complexité qui conduit à une faible cohérence des structures spatiales des pluies journalières.…”

Section: Leunclassified

Application du processus de Markov sur les occurrences des précipitations journalières au Congo-Brazzaville

Samba

Mpounza

2005

Comptes Rendus. Géoscience

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Cette étude concerne l'occurrence des précipitations journalières au cours des saisons pluvieuses dans différentes localités du Congo-Brazzaville. Le modèle de la chaîne de Markov a été utilisé pour déterminer, dans chaque station, les probabilités pour les séquences pluvieuses et non pluvieuses, ainsi les probabilités de transition. Les principaux résultats sont les suivants, dans l'espace congolais : la dépendance de l'occurrence des précipitations d'un jour vis-à-vis du jour précédent ; l'existence de deux domaines climatiques (équatorial au nord et tropical humide au sud) ; la cohérence à petite échelle spatiale des précipitations. Pour citer cet article : G.

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“…This study assesses trends of minimum and maximum temperature in the Congo-Brazzaville from 1932 to 2010, a period for which reliable temperatures database are available. A large number of studies documented climate variations and changes across the 20 th century in West Africa, e.g., [1]- [7], Southern Africa, e.g., [8] [9] and Eastern Africa, e.g., [10]- [14]. Mpounza et al [15] have shown a rise of temperature of about 1˚C in Brazzaville for the period , with values ranging from 0.6˚C to 1.6˚C across the rest of the country.…”

Section: Introductionmentioning

confidence: 99%

Minimum and Maximum Temperature Trends in Congo-Brazzaville: 1932-2010

Samba¹,

Nganga²

2014

ACS

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Maximum and minimum temperatures time series of Congo-Brazzaville are analyzed for trend and discontinuities over the period 1932 to 2010. Temperatures series show an irregular increase. A total of 8 synoptic stations show positive trends in their annual mean maximum temperature series, and 7 of them are significant, with higher trends for urban stations. Annual mean minimum temperature showed 6 stations having positive trends. This increase is in relation with observations at regional scale. However, the differences are observed between large towns (Brazzaville and Pointe-Noire), and small or rural towns (Dolisie, Sibiti, Impfondo, Djambala). Trends in diurnal temperature range (DTR) are large positive trends in maximum temperature that are mainly observed in cities. The curve of DTR shows a decreasing trend which indicates the increasing of minimum temperatures. The effects of urbanization on temperature trends are investigated. Most stations regarded as urban stations are still useful for trend analysis; being situated on the suburban of the studied cities, they are therefore, not substantially influenced by the urban heat island.

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Cohérence intrasaisonnière de la variabilité pluviométrique interannuelle en Afrique du Sud

Cited by 8 publications

References 0 publications

ENSO and IOD teleconnections for African ecosystems: evidence of destructive interference between climate oscillations

ENSO and IOD teleconnections for African ecosystems: evidence of destructive interference between climate oscillations

Application du processus de Markov sur les occurrences des précipitations journalières au Congo-Brazzaville

Minimum and Maximum Temperature Trends in Congo-Brazzaville: 1932-2010

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