Variations of the hydrological load induced by ENSO phenomenon.

ROMINA DE LOS ANGELES GALVÁN; MICAELA CARBONETTI; MAURICIO GENDE; CLAUDIO BRUNINI

La Plata

Encuentro; HOSGO meeting; 2017

AGGO-CONICET

El Niño-Southern Oscillation (ENSO) is an atmospheric-oceanic phenomenon that originates in the equatorial Pacific Ocean. It is characterized by two phases: the warm or ?El Niño? phase, and the cold or ?La Niña? phase. They respectively refer to a significant increase or decrease of the surface temperature of the Pacific Ocean with respect to normal values.One of the main consequences of this abnormality is an alteration of the hydrological cycle in the rainfall patterns in South American and Caribbean region. Such disturbance can cause non-periodic variations in both the rainfall patterns and water body storages located on the surface or near it. The immediate consequence is the pressure that such bodies exert on the earth´s crust change. They can cause geometric movements of the earth´s crust and gravity measurement changes.This presentation is focused on the geometric effects of this phenomenon on the GNSS station positions of SIRGAS-CON network. Time periods when El Niño or La Niña occurred are recognized using the Oceanic Niño Index (ONI). The impact that each event has had on rainfall patterns and on total water storage over South America and the Caribbean is analyzed. Regions of characteristic behavior of each phase are recognized using global precipitation model CMAP and GRACE mission data. GNSS sites located in regions where the phenomenon causes great impact are selected and the effect on the vertical component is evaluated.