The Use of CHIRPS to Analyze Historical Rainfall in Colombia

Wednesday, 17 December 2014
Diego H Pedreros1, Alexander Rojas2, Christopher Funk1, Pete Peterson3, Martin F Landsfeld3 and Gregory J Husak4, (1)USGS, Baltimore, MD, United States, (2)Instituto de Hidrologia, Meteorologia y Estudios Ambientales (IDEAM), Colombia, Bogota, Colombia, (3)University of California Santa Barbara, Santa Barbara, CA, United States, (4)University of California Santa Barbara, Geography, Santa Barbara, CA, United States
The climate of Colombia is characterized by a high spatial and temporal variability of precipitation, temperature, and wind due to its tropical location, a complex terrain (coastal regions, plains, and three mountain ranges with strong gradients of elevation [0 - 4500 m]), and the influence of two oceans. Given the high variability of rainfall, achieving a complete and accurate coverage of the country based on in-situ measurements becomes a difficult task, so satellite measurements provide a good alternative. The Meteorological Office of Colombia has joined forces with the U.S. Geological Survey Famine Early Warning Systems Network program to integrate historical data from rainfall stations with the Climate Hazards Infrared Precipitation with Stations satellite-derived rainfall estimates to develop a historical database from 1981-2013 at a temporal resolution of 5 days and a spatial resolution of 5 km. This database accurately describes key characteristics of precipitation such as bimodal and single mode regimes, for example 1) regions such as the western part of the country and the mountainous region of the Andes in which a bimodal regime is present showing two rainy seasons, the first rainy season between the months of April and May and a second season from September to November, and 2) areas with a single mode regime during July-August in the eastern plains of the country and another focused on May-October for the Caribbean region in the northern part of the country. Furthermore, correlating the sea surface temperature in El Niño 3.4 region and the new historical rainfall database corroborated results from previous studies showing, with high statistical significance, a negative correlation over central, western and northern Colombia, as well as a positive correlation for the eastern and southern parts of the country. The study also confirms that the relationship mentioned above is stronger (greater correlation) in the months of lowest precipitation.