Interpretation of link fluctuations in climate networks during El Nino periods

Recent work has shown that the topologies of functional climate networks are sensitive to El Nino events. One important interpretation of the findings was that parts of the globe act in correlated relationships which become weaker, on average, during El Nino periods (this was shown using monthly averaged data where no time lag is required, and with daily averaged data where time lags were utilized). In contrast to this, we show that El Nino periods actually exhibit higher correlations than Normal climate conditions, while typically having lower correlations than La Nina periods. We also show that it is crucial to establish the sensitivity and the robustness of a given method used to extract functional climate networks -parameters such as time lags can significantly influence and even totally alter the outcome. Copyright (C) EPLA, 2013