Investigation of an Intense Dust Outbreak in the Mediterranean Using XMed-Dry Network, Multiplatform Observations, and Numerical Modeling

Umberto Rizza,Mauro Morichetti,Giorgio Passerini,Enrico Mancinelli,Konrad Kandler,Melanie Eknayan,Michael Nolle,Konstantinos Eleftheriadis,Pierina Ielpo,Vasiliki Vasilatou,Simone Virgili

doi:10.3390/app11041566

Abstract

The Weather Research and Forecasting (WRF) model with online coupled chemistry (WRF-Chem) is applied to study an intense Saharan dust outbreak event affecting the Italian peninsula in 15 and 16 April 2018. According to the MODIS retrievals, this intrusion was characterized by an intense aerosol optical depth (AOD) peak value in the southern Mediterranean. Measurements within the Dry Deposition Network Across the Mediterranean (XMed-Dry) are compared with the output of the WRF-Chem model. XMed-Dry samples from Lecce (Italy), Athens (Greece) and San Lawrenz/Gozo (Malta) were analysed with respect to aerosol particle size distribution, relative dust contribution, and composition. The discrepancy between the model and measured deposition indicate the need to formulate in WRF-Chem more sophisticated deposition schemes, this will need to evaluate the sensitivity of the results to the precise particle size limits chosen for the aerosol model. Moreover, satellite retrievals from MODIS sensors elaborated with the MAIAC algorithm, Aeronet stations, and measurements of PM10 at the selected sites were also considered. In a numerical domain that spans the Mediterranean and the northern Saharan desert, two different dust emission schemes, namely Gocart-AFWA and the Shao-2001, were tested and compared with multiplatform observations for simulation period covering the dust outbreak. Actual results indicate that both emission schemes would benefit from replacing the static erodibility map and soil particle distribution with remote sensed and in-situ observational data.

Highlights

The selected dataset concerns the ERA5 hourly data on pressure levels (1979 to present) from which the geopotential at 500 hPa may be downloaded in GRIdded Binary (GRIB) format
ERA5 represents the fifth generation of European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis of the global climate
If we considermodel particulate mass concentration (PM10 ) data, in the second column of Tables 7–9, we have reported the daily mean PM10 concentrations measured at Gharb (Malta; Table 7), Lecce (Table 8), and Athens (Table 9) monitoring stations

Summary

Introduction

The Intergovernmental Panel on Climate Change [1] has recognized mineral dust as the main component of atmospheric aerosols, and considered it as an ‘essential climate variable’. It may be defined as one of the largest natural aerosol sources and influencing significantly the weather and climate system [2]. Aerosol particles influence climate by modifying directly the global energy budget by scattering and absorbing long- and shortwave radiation [3] and interacting with clouds modifying the development and occurrence of precipitation (indirect effects).

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Results

Conclusion