Modulation of Saharan dust export by the North African dipole

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Rodríguez González, Sergio, Cuevas Agulló, Emilio, Prospero, Joseph M., Alastuey, Andrés, Querol, Xavier, López Solano, Javier, García Álvarez, María Isabel, Alonso Pérez, Silvia
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union 2015
• Subjects: Variabilidad climática; Distribución de partículas de polvo; Climate variability; Distribution of dust; North Atlantic
• Online Access: https://hdl.handle.net/20.500.11765/507

We have studied the relationship between the long-term interannual variability in large-scale meteorology in western North Africa – the largest and most active dust source worldwide – and Saharan dust export in summer, when enhanced dust mobilization in the hyper-arid Sahara results in maximum dust impacts throughout the North Atlantic. We address this issue by analyzing 28 years (1987–2014) of summer averaged dust concentrations at the high-altitude Izaña observatory (~ 2400 m a.s.l.) on Tenerife, and satellite and meteorological reanalysis data. The summer meteorological scenario in North Africa (aloft 850 hPa) is characterized by a high over the the subtropical Sahara and a low over the tropics linked to the monsoon. We measured the variability of this high–low dipole-like pattern in terms of the North African dipole intensity (NAFDI): the difference of geopotential height anomalies averaged over the subtropics (30–32° N, Morocco) and the tropics (10–13° N, Bamako region) close to the Atlantic coast (at 5–8° W). We focused on the 700 hPa standard level due to dust export off the coast of North Africa tending to occur between 1 and 5 km a.s.l. Variability in the NAFDI is associated with displacements of the North African anticyclone over the Sahara and this has implications for wind and dust export. The Izaña GAW program is funded by AEMET and by the Minister of Economy and Competitiveness of Spain (POLLINDUST, CGL2011-26259). J. M. Prospero’s research is supported by NSF grant AGS-0962256.