1. Climatic gradients along the windward slopes of Mount Kenya and their implication for crop risks. Part 1: climate variability
- Author
-
Camberlin, Pierre, Boyard-Micheau, Joseph, Philippon, Nathalie, Baron, Christian, Leclerc, Christian, Mwongera, Caroline, Centre de Recherches de Climatologie (CRC), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Territoires, Environnement, Télédétection et Information Spatiale (UMR TETIS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-AgroParisTech-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Centre de Recherches de Climatologie ( CRC ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Amis/Agronomie/Ecotrop, Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-AgroParisTech-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)
- Subjects
Zone agroclimatique ,Précipitation ,P40 - Météorologie et climatologie ,[SDE.MCG]Environmental Sciences/Global Changes ,Climat de montagne ,Évapotranspiration ,Saison humide ,[ SDE.MCG ] Environmental Sciences/Global Changes ,Variation saisonnière ,[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology ,Terre en pente ,Microclimat ,[ SDU.STU.CL ] Sciences of the Universe [physics]/Earth Sciences/Climatology ,ComputingMilieux_MISCELLANEOUS ,Zone tropicale - Abstract
In tropical mountains, the way topographical gradients translate in terms of intra-seasonal and interannual climate variability (especially rainfall and evapotranspiration) is relatively unknown, yet it is an important issue for agriculture and food security. The eastern slopes of Mount Kenya, in East Africa, with their wide range of agro-ecological conditions, are appropriate for the study of these aspects. Daily (monthly) rainfall data from 11 (24) stations at different elevations and exposures are collected for the period 1961-2006. For the elevation belts suitable for farming and agro-pastoral activities, mostly below 2000 m, it is found that not all rainfall characteristics co-vary with altitude. Four distinct behaviours are revealed: (1) Parameters which show a relatively regular increase/decrease with elevation. This is the case for the duration of the two rainy seasons found across the region, and the mean onset and cessation dates, (2) Parameters which show a relatively uniform pattern throughout the region, with little differences both horizontally and vertically. This applies to the interannual variability of the October-December seasonal rains, which are quite homogeneously modulated by Indian Ocean sea-surface temperatures (SSTs), (3) Parameters markedly influenced by exposure. This applies to daily rainfall intensities, which peak along the southeast-facing slopes, whatever the altitude. The frequency of rainy days shows both a vertical gradient and some influence of exposure, (4) Parameters which show very weak spatial coherence, or pronounced vertical discontinuities. This is obvious for the cessation date of the March-May rains, whose poorly organized interannual variability contrasts with that of the onset. Variables involved in potential evapotranspiration (ET0) computation display either a strong (maximum temperature) or a weak (global radiation) vertical coherence, reflecting the existence/absence of an elevation control on the mean distribution of these variables. However, the interannual variations of global radiation have the strongest influence on those of ET0.
- Published
- 2014
- Full Text
- View/download PDF