Oceanic versus terrestrial origin of El Niño Southern Oscillation-associated continental precipitation anomalies

Abstract

Precipitation is significantly influenced by the El Niño Southern Oscillation (ENSO), which is considered to be the most important factor that brings about climate variability. In this study, the asymmetry of the origin of continental precipitation anomalies during El Niño and La Niña events was investigated. An already validated Lagrangian approach was used to determine the proportion of the total Lagrangian precipitation that is of oceanic and terrestrial origin. Further, the role of these components of the Lagrangian precipitation in regions with significant precipitation anomalies during the ENSO was investigated. A two-phase asymmetric behavior of precipitation, particularly in tropical regions, was obtained. For some of these regions, precipitation anomalies based on other datasets were also calculated to confirm the observed changes, and for these regions, it was observed that in all cases, the calculated anomaly of Lagrangian precipitation agreed with the precipitation change. The percentage of precipitation of oceanic origin was higher in most of these regions. However, it was observed that an increase in the percentage of precipitation of oceanic origin did not bring about a general increase in precipitation for all the regions, revealing the importance of precipitation of terrestrial origin during both phases of the ENSO.

Keywords: ENSO; Lagrangian precipitation; oceanic and terrestrial components of Lagrangian precipitation; precipitation.