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This study detects climate trends and variability from precipitation and temperature observations in Ecuador and assesses their links to the El Niño Southern Oscillation (ENSO) for the period 1966-2011, using the El Niño 1+2 and El Niño 3.4 indices. Excluding the Amazonian region (for which there is a lack of data), two main regions were distinguishable in terms of variability and trends among climate variables, especially for precipitation. In general, there was no trend in precipitation for the coastal region, and a very close relationship between the magnitude and seasonal distribution of precipitation and the El Niño 1+2 variability was found. In contrast, for the mountainous region (the Andes), there was an increase of precipitation during the study period, and a signal of El Niño 3.4 influence was detected. Temperatures were spatially homogeneous and showed an intense warming trend, except for maximum temperatures in the coastal region. The El Niño 1+2 influence on temperature was large from January to July. The results provide evidence of the close control exerted by the ENSO, especially in the coast of Ecuador, as well as for the occurrence of significant warming across the country independent of the ENSO phenomenon.

16In this study, we analyzed the influence of El Niño -Southern Oscillation (ENSO) on the spatio-17 temporal variability of droughts in Ecuador for a 48-year period (1965-2012). Droughts were quantified 18 from 22 high-quality and homogenized time series of precipitation and air temperature by means of the 19 Standardized Precipitation Evapotranspiration Index (SPEI). In addition, the propagation of two different 20 ENSO indices (El Niño 3.4 and El Niño 1+2 indices) and other atmospheric circulation processes (e.g., 21vertical velocity) on different time-scales of drought severity were investigated. The results showed a 22 very complex influence of ENSO on drought behavior across Ecuador, with two regional patterns in the 23 evolution of droughts: (i) the Andean chain with no changes in drought severity, and (ii) the Western 24 plains with less severe and frequent droughts. We also detected that drought variability in the Andes 25 mountains is explained by the El Niño 3.4 index (sea surface temperature [SST] anomalies in the central 26 Pacific), whereas the Western plains are much more driven by El Niño 1+2 index (SST anomalies in the 27 eastern Pacific). Moreover, it was also observed that El Niño and La Niña phases enhance droughts in the 28Andes and Western plains regions, respectively. The results of this work could be crucial for predicting 29 and monitoring drought variability and intensity in Ecuador. 30

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In this study, the spatio-temporal variability and trends of droughts across Bolivia between 1955 and 2012 were investigated using two climate drought indices: the Standardized Precipitation Index (SPI), which is based on precipitation data, and the Standardized Precipitation Evapotranspiration Index (SPEI), which is based on the difference between the precipitation and the reference evapotranspiration (ETo). We found that the average drought conditions across the country showed a temporal behaviour mainly characterized by decadal variations. The spatial pattern of drought evolution showed marked differences between the Amazonian region and the Bolivian Altiplano. Both regions showed different drought periods, a lower frequency of drought variability in the Amazon region and trends towards drier conditions in the Altiplano, mainly due to a higher atmospheric water demand as a consequence of increased ETo. We also showed that inclusion of ETo, obtained from maximum and minimum temperature records, increased the spatial heterogeneity of the drought evolution in relation to the evolution observed when only precipitation droughts were considered. The SPEI, the calculation of which includes precipitation and ETo, indicated intensification in drought severity in the last years analysed relative to the pattern found when precipitation droughts alone were considered, and also indicated an increase in the magnitude and duration of drought events. The potential for increasing drought conditions under various climate change scenarios is discussed.