title: An anomalous African dust event and its impact on aerosol radiative forcing on the Southwest Atlantic coast of Europe in February 2016.
abstract: A desert dust (DD) event that had its origin in North Africa occurred on the 20th-23rd of February 2016. The dust transport phenomenon was exceptional because of its unusual intensity during the coldest season. A historical dataset (2006-2015) of February meteorological scenarios using ECMWF fields, meteorological parameters, aerosol optical properties, surface O3and AOD retrieved from MODIS at the El Arenosillo observatory (southwestern Spain) were analysed and compared with the levels during the DD event to highlight its exceptionality. Associated with a low-pressure system in western North Africa, flows transported air from the Sahel to Algeria and consequently increased temperatures from the surface to 700hPa by up to 7-9°C relative to the last decade. These conditions favoured the formation of a Saharan air layer. Dust was transported to the north and reached the Western Mediterranean Basin and the Iberian Peninsula. The arrival of the DD event at El Arenosillo did not affect the surface weather conditions or ozone but did impact the aerosol radiative forcing at the top of atmosphere (RFTOA). Aerosol radiative properties did not change relative to historical; however, the particle size and the amount of the aerosol were significantly higher. The DD event caused an increase (in absolute terms) of the mean aerosol RFTOAto a value of -8.1Wm-2(long-term climatological value ~-1.5Wm-2). The aerosol RFTOAwas not very large relative other DD episodes; however, our analysis of the historical data concluded that the importance of this DD event lay in the month of occurrence. European phenological datasets related to extreme atmospheric events predominantly reflect changes that are probably associated with climate change. This work is an example of this phenomenon, showing an event that occurred in a hotspot, the Saharan desert, and its impact two thousand km away.
authors.affiliation: Atmospheric Sounding Station - El Arenosillo, Atmospheric Research and Instrumentation Branch, INTA, Mazagón, Huelva 21130, Spain. Electronic address: sorribasm@inta.es.
authors.forename: M
authors.initials: M
authors.lastname: Sorribas
authors.affiliation: Atmospheric Sounding Station - El Arenosillo, Atmospheric Research and Instrumentation Branch, INTA, Mazagón, Huelva 21130, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Adame
authors.affiliation: University of Colorado, CIRES, Boulder, CO 80309, USA.
authors.forename: E
authors.initials: E
authors.lastname: Andrews
authors.affiliation: Atmospheric Sounding Station - El Arenosillo, Atmospheric Research and Instrumentation Branch, INTA, Mazagón, Huelva 21130, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Yela
keywords: Aerosol optical properties; Climate change; Extreme meteorological event; Saharan desert dust