Synoptic attributions of extreme precipitation in the Atacama Desert (Chile)
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Synoptic attributions of extreme precipitation in the Atacama Desert (Chile) Oliver Meseguer‑Ruiz1 · Paulina I. Ponce‑Philimon1 · Alexis Baltazar1 · Jose A. Guijarro2 · Roberto Serrano‑Notivoli3 · Jorge Olcina Cantos4 · Javier Martin‑Vide5 · Pablo Sarricolea6 Received: 4 June 2020 / Accepted: 2 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Northern Chile is a region characterised by an extremely dry climate; however, there is a brief rainy season from December to March (austral summer), mainly above 3000 m a.s.l. It is interesting to consider where the humid air masses that generate such rain come from. For this purpose, daily precipitation data from 161 meteorological stations located in this area (18° S–19° S) were considered, and four clusters formed by k-means clustering. For each cluster, days of extreme precipitation (above 90th percentile) were selected to obtain flow strength (F), direction (D), and vorticity (Z) for each event according to the Jenkinson and Collison (JC) method. The back trajectory, for the previous 72 h, of air masses affecting the centroid of each cluster was determined by means of the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The analyses were carried out at sea level (1013 hPa) and in the middle (500 hPa) and upper (250 hPa) troposphere. Surface circulation was not a determining factor in the occurrence of extreme events, but it did influence circulation at 500 and 250 hPa. For stations located in the northern Altiplano, moisture advection from the Amazon basin is evident due to the configuration of the Bolivian high—an upper level anticyclone that develops over the Bolivian Altiplano during austral summer. For stations located in the southern part of the study area, the main source of moisture is the Pacific Ocean, and the weather is related to the arrival of frontal systems and to the configuration of cut-off low pressure systems in the mid-troposphere. Keywords Back trajectory · Extreme precipitation · Jenkinson and Collison method · HYSPLIT model · Northern Chile
1 Introduction
* Oliver Meseguer‑Ruiz [email protected] 1
Departamento de Ciencias Históricas y Geográficas, Universidad de Tarapacá, 2222, 18 de Septiembre, Arica, Chile
2
State Meteorological Agency (AEMET), Balearic Islands Office, Palma, Spain
3
Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD-CSIC), Avda. Montañana 1005, Zaragoza, Spain
4
Instituto Interuniversitario de Geografía, Universidad de Alicante, Edificio de Institutos Universitarios, Apartado de Correos 99, 03080 Alicante, Spain
5
Departamento de Geografía, Universidad de Barcelona, Montalegre 6‑8, 08001 Barcelona, Spain
6
Departamento de Geografía, Universidad de Chile, Portugal 84, Torre Chica, Santiago, Chile
The Atacama Desert is one of the most arid regions in the world, covering a vast area including parts of Chile, Argentina, Bolivia, and Peru. In addition to severe aridity, this region is characteris
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