Climate Variability

Abstract

In this paper variability refers to the range of values between particular climate maxima and minima over a period of time (Mitchell 1976). Atmospheric variability in space and time can significantly alter the response of the ecosystem. For instance, comprehensive studies emphasise notable relations of reproduction phenology to climate in tropical rain forests (e.g. Hamann 2004). Three types of relevant spatio-temporal heterogeneities are dicussed in this chapter: 1. Long-term and quasi-periodic oscillations of meteorological conditions; 2. Seasonal changes of selected meteorological parameters (clouds and precipitation), as a supplement to information already presented in Chapter 8; 3. The diurnal course of rainfall. Specific year-to-year variability, quasi-periodic oscillations and extremes of the meteorological parameters are of ecological importance for the study area. In this section we briefly discuss: 1. The influence of the quasi-periodic El Niño-Southern Oscillation (ENSO) phenomenon = El Niño (EN) and La Niña (LN) events; 2. Specific circulation patterns which lead to very low temperatures in the RBSF. The analysis of rainfall and temperature data of several EN/LN events since 1972 in Ecuador has shown that the phenomenon mainly affects the coastal plains with floods (EN) or droughts (LN; e.g. Bendix 2000, 2004). Teleconnections to the highland and the eastern escarpment of the Andes are irregular and less clear. For the eastern slopes, a slight tendency exists towards reduced (EN) or enhanced (LN) E. Beck et al. (eds.), Gradients in a Tropical Mountain Ecosystem of Ecuador. 281 Ecological Studies 198.