Linking Anomalous Moisture Transport And Drought Episodes in the IPCC Reference Regions

Abstract

AbstractDroughts are complex and may be triggered by different mechanisms, such as atmospheric circulation, moisture transport, and thermodynamic processes. Significant research has been completed to characterize precipitation in the Intergovernmental Panel on Climate Change (IPCC) reference regions (RRs), but a systematic analysis of atmospheric transport linked to drought episodes is still missing. This article describes a catalog in which the drought episodes over the RRs are identified during 1980–2015, and the role of the moisture transport anomalies from the respective major climatological moisture sources during the most severe meteorological drought episode registered for each RR is analyzed. For each of the 27 RRs defined in the IPCC Fifth Assessment Report, drought episodes were identified at 1-, 6-, and 12-month time scales through the standardized precipitation evapotranspiration index (SPEI). SPEI values were computed using time series of the monthly precipitation and atmospheric evaporative demand (AED) averaged over each RR. The approach, which was applied to both identify the major climatological moisture sources and sinks for each RR and to investigate anomalies in moisture transport during the episode, is based on the Lagrangian flexible particle dispersion model (FLEXPART), integrated with the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim) data. For each RR, the following components were analyzed: a) moisture uptake over sources, b) moisture supply from the sources into the RR, and c) moisture supply from the RR into its sink. Although performed for just one case, this analysis illustrates how the moisture transport may impact the RR during extreme conditions. The results are organized in a web page available to the scientific community and stakeholders.