From Advection to Precipitation: Reconstructing the Monsoons in Historical Times by Using Old Wind Measurements

• Main Authors: Gallego, David, Ordóñez-Pérez, Paulina, Ribera, Pedro, Peña-Ortiz, Cristina, García Herrera, Ricardo, Vega, Inmaculada, Paula Gómez, Francisco de
• Other Authors: Ministerio de Economía y Competitividad (España)
• Format: Conference Object
• Language: English
• Published: 2016
• Subjects: Monsoons; Sahel; Climate indices; Monson; North Atlantic
• Online Access: http://hdl.handle.net/10261/190146; https://doi.org/10.13039/501100003329

Trabajo presentado en el 8th EGU Leonardo Conference, celebrado en Orense (España), del 25 al 27 de octubre de 2016 The precipitation associated to the West African Monsoon is strongly modulated by the oceanatmosphere interaction in the tropical North Atlantic. During the last four decades, this monsoon has experienced a strong decline in its strength which has resulted in large shortages of precipitation in populated areas such as the Sahel, with the consequent humanitarian crisis. The improvement of our understanding of the long term variability of this monsoon and its relation to its moisture sources is therefore, of paramount importance. The historical evolution of the West African Monsoon has been usually addressed by combining instrumental precipitation series in northwest Africa. Unfortunately,reliable meteorological series in this region are only available since the beginning of the 20th Century thus limiting our understanding of the significance of the unusually persistent drought period. As most of the moisture involved in the generation of monsoonal precipitations came from the ocean, it is feasible the construction of an index characterising the monsoon strength by using wind records. In this work, by using exclusively wind direction measures taken aboard thousands of sailing ships circumnavigating Africa, we have assembled a new index measuring the strength of the West African Monson since 1839. Our new reconstruction has evidenced for the first time, that this monsoon can experience persistent periods of high activity, as it seems to have occurred between 1840 and 1890. Additionally, we have been able to study the relation of the West African Monsoon with several climatic patterns. Ourresults suggests that since the beginning ofthe weak monsoon period starting in the 1970s, the correlations with different climatic patterns such as the Atlantic “El Niño” have changed significantly in relation to those of the previous century. This research was funded by the Spanish Ministerio de Economía y ...