Seasonality of Rainfall in Colombia

The knowledge of the annual cycle of rainfall is of primary concern for many socioeconomic activities such as agricultural planning, electricity generation, and flood and other disaster management. The annual cycle of rainfall in Colombia has been studied so far using monthly or quarterly information, identifying zones with the unimodal regime (one wet season and one dry season) over the Caribbean, the Amazon, and the Pacific regions and zones with the bimodal regime (two wet and two dry seasons) in the Andes. This paper explores the annual rainfall cycle in Colombia on a daily basis using historical records of 1,706 rain gauges and the Climate Hazards Group Infrared Precipitation with Station data precipitation data set. We found four types of annual precipitation regimes: unimodal, bimodal, mixed, and aseasonal. The unimodal regime predominates in the low-altitude zones of the east and the north, the bimodal and mixed regimes over the Andes mountain range, and the aseasonal in the Pacific region. These results improve the statistical diagnosis of the spatial variability of the rainfall seasonality in Colombia. This phenomenon, however, is still far from being fully understood in its hydroclimatic context. The annual migration of the Intertropical Convergence Zone is not enough to explain the diversity of rainfall regimes in Colombia. Local factors such as topography and land cover could play an important role in the occurrence and duration of rainfall seasons.