Three-dimensional evolution of Saharan dust transport towards Europe based on a 9-year EARLINET-optimized CALIPSO dataset

Abstract

Abstract. In this study we use a new dust product developed using CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) observations and EAR-LINET (European Aerosol Research Lidar Network) measurements and methods to provide a 3-D multiyear analysis on the evolution of Saharan dust over North Africa and Europe. The product uses a CALIPSO L2 backscatter product corrected with a depolarization-based method to separate pure dust in external aerosol mixtures and a Saharan dust lidar ratio (LR) based on long-term EARLINET measurements to calculate the dust extinction profiles. The methodology is applied on a 9-year CALIPSO dataset (2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) and the results are analyzed here to reveal for the first time the 3-D dust evolution and the seasonal patterns of dust over its transportation paths from the Sahara towards the Mediterranean and Continental Europe. During spring, the spatial distribution of dust shows a uniform pattern over the Sahara desert. The dust transport over the Mediterranean Sea results in mean dust optical depth (DOD) values up to 0.1. During summer, the dust activity is mostly shifted to the western part of the desert where mean DOD near the source is up to 0.6. Elevated dust plumes with mean extinction values between 10 and 75 Mm −1 are observed throughout the year at various heights between 2 and 6 km, extending up to latitudes of 40 • N. Dust advection is identified even at latitudes of about 60 • N, but this is due to rare events of episodic nature. Dust plumes of high DOD are also observed above the Balkans during the winter period and above northwest Europe during autumn at heights between 2 and 4 km, reaching mean extinction values up to 50 Mm −1 . The dataset is considered unique with respect to its potential applications, including the evaluation of dust transport models and the estimation of cloud condensation nuclei (CCN) and ice nuclei (IN) concentration profiles. Finally, the product can be used to study dust dynamics during transportation, since it is capable of revealing even fine dynamical features such as the particle uplifting and deposition on European mountainous ridges such as the Alps and Carpathian Mountains.

Are EARLINET and AERONET climatologies consistent? The case of Thessaloniki, Greece

“…In the FT the dust component can still be considered dominant, since the BAE is shifted towards values closer to the transported-dust Ångström of 0.5 ± 0.5 reported within EARLINET (Müller et al, 2007). Indeed, Marinou et al (2017) show that the dust component during the transportation episodes over Greece in summer (JAS) is more dominant above 2 km, which is consistent with our findings.…”

Triple-wavelength depolarization-ratio profiling of Saharan dust over Barbados during SALTRACE in 2013 and 2014

“…In these profiles, the particle linear depolarization ratio is recalculated from L2 perpendicular and total backscatter profiles, to improve the accuracy compared to the original CALIPSO L2-Version 3 product, which has a known error Amiridis et al, 2013). Furthermore, several quality control procedures and filtering criteria are applied in the data set as described in Marinou et al (2017).…”

GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures

“…Dust transport, while less frequent during the dry period, is still observed (e.g. Marinou et al, 2017) and is characterized by a transportation pattern through the free troposphere and weaker vertical mixing of the dust layers (e.g. Kalivitis et al, 2007).…”