Defense
Student: Wendy Paola Arias García
Program: Meteorology
Title: "Analysis of the influence of El Niño and La Niña events on precipitation, temperature, and glacier area in the Colombian nevados (1985–2024)"
Advisor: Prof. Dr. Tércio Ambrizzi
Judging Comitee:
- Prof. Dr. Tércio Ambrizzi - Chair and Advisor - IAG/USP
- Dr. Mathias Vuille - University at Albany, USA
- Dr. Bijeesh Kozhikkodan Veettil - Van Lang University, Vietnam
Other Members:
- Prof. Dr. Dra. Rosmeri Porfirio da Rocha - IAG/USP
- Profa. Dr. Dra. Maria Elisa Siqueira Silva - FFLCH/USP
- Dr. José Antonio Marengo Orsini - Cemaden
Abstract:
In this study, the impact of the oceanic component of the natural phenomenon El Niño–Southern Oscillation (ENSO), in its El Niño and La Niña events, on precipitation, temperature, and glacier dynamics in the Colombian nevados is analyzed. Their traditional names in Indigenous Colombian languages are included in parentheses: Sierra Nevada de Santa Marta (Chundua), Sierra Nevada El Cocuy o Güicán (Zizuma), Nevado del Ruiz (Kumanday), Nevado de Santa Isabel (Poleka Kasué), Nevado del Tolima (Dulima), and Nevado del Huila (Wila), for the period 1985–2024. For this purpose, Total Monthly Precipitation (Pt) and Mean Monthly Air Temperature (Ta) data from meteorological stations and the ERA5-Land reanalysis were compared at locations near these nevados. In addition, variations in glacier area were evaluated in relation to El Niño and La Niña events, identified using the Oceanic Niño Index (ONI). This analysis made it possible to assess how variations in Pt, Ta, and glacier area respond to ENSO events. The results demonstrate that ENSO events exert a consistent influence on Ta in the analyzed mountains, with El Niño episodes associated with a predominance of positive anomalies and La Niña episodes with a predominance of negative anomalies. Pt exhibits a spatially heterogeneous response, suggesting modulation by local and regional factors. Regarding glacier area, indications of reduction are observed during several El Niño events, whereas partial conservation or increases are identified during some La Niña events. However, the absence of complete records precludes the establishment of a consistent pattern. Finally, event intensity shows a clearer relationship with temperature anomalies than with variations in precipitation or glacier area.
Keywords: Colombian nevados, El Niño, La Niña, ENSO, ERA5-Land, reanalysis, precipitation, temperature, glacier area, glaciers