Abstract

In the present study, dust aerosol episodes (DAEs) in the broader Mediterranean Basin (MB) are investigated over a 15-year (2005–2019) period using contemporary MODIS Collection 6.1 and OMI OMAERUV satellite data and a satellite algorithm applying a thresholding technique on selected aerosol optical properties. The algorithm operates on a daily and 1° × 1° pixel level basis, first identifying the presence of dust, and consequently requiring the presence of unusually high dust loads, i.e., dust episodes. Apart from the presence of pixel-level DAEs, an extended spatial coverage of dust is also required. Thus, a specific day is characterized as a Dust Aerosol Episode Day (DAED), when at least 30 episodic pixels exist over Mediterranean Basin (MB). According to the algorithm results, 166 DAEDs (116 strong and 50 extreme) took place in the MB from 2005 to 2019. Most DAEDs occurred in spring (47%) and summer (38%), while a different seasonality is observed for strong and extreme episodes. The interannual variability of DAEDs reveal a decreasing trend, which is however not statistically significant.

Highlights

  • The operation of the satellite algorithm utilized in the present study is based on MODIS Aerosol Optical Depth (AOD) and OMI Aerosol Index (AI) data and achieves the identification of Dust Aerosol Episodes (DAEs) over the broader Mediterranean Basin (MB) on a daily and 1° × 1° pixel level basis

  • Dust aerosol episodes over the broader MB were identified on a 1° × 1° pixel level and on a 15-year study period (2005–2019) with an algorithm using contemporary MODIS and OMI satellite data

  • (84.8%) occurred in spring and summer, and the remaining 15.2% in autumn and winter, during September, October, January and February, while no episodes at all were identified in November and December

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Summary

Introduction

The emitted dust remains in the atmosphere from a few hours up to several days, while under favorable conditions it is transported far from its sources. During this transport, the physical and chemical properties of dust can change, affecting its action as Cloud Condensation Nuclei (CNN) or Ice Nuclei (IN) as well as its interaction with radiation. The physical and chemical properties of dust can change, affecting its action as Cloud Condensation Nuclei (CNN) or Ice Nuclei (IN) as well as its interaction with radiation Given that it acts as CNN and/or IN, dust modifies the physical and optical properties of clouds and their lifetime and precipitation efficiency. It was found [2]

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