Impact of ENSO on East African ecosystems: a multivariate analysis based on climate and remote sensing data

1 The El Nino-Southern Oscillation (ENSO) is an important driver of inter-a nnual variations in climate and ecosystem productivity in tropical regions. Most previous studies have analysed ENSO-induced changes in climate based on a single variable, such as rainfall. Also, it is generally assumed that the ENSO impact in East Africa is geographically uniform. 2 The objective of this study is to improve understanding of the impact of ENSO on East African ecosystems, by measuring teleconnections between an EN SO index and a number of ecosystem variables in a spatially explicit way an d for different time lags. We analysed the spatial patterns of teleconnecti ons in the region by combining time series of climate variables measured fo r meteorological stations with time series of a vegetation index and surfac e temperature data measured by remote sensing. 3 Our results confirm the ENSO impact on the climatic and ecological variab ility in East Africa. However, the pattern of teleconnections is much more complex than generally assumed, both in terms of spatial distribution and i mpact on different ecosystem variables. Not all climate and land surface va riables are teleconnected to ENSO in the same way, which leads to a complex impact of ENSO on the ecosystem. Moreover, the ENSO impact is highly diffe rentiated in space, as the direction, magnitude and timing of this impact a re controlled by the local climate system, the presence of large lakes, pro ximity to the coast and, possibly, local topography and land cover.