Conferenza: The 9th International Workshop on Sand / Dust storm and Associated Dustfall - Tenerife (Spagna). 

Periodo: 22-24 Maggio 2018

Autori: F. Lucarelli, F. Guarnieri, C.Busillo, F. Calastrini, G. Calzolai, M. Chiari, S. Nava, S. Becagli, R. Traversi 

Abstract:
Saharan dust episodes can be observed over the Mediterranean region several times a year, affecting PM10 concentrations. In particular, the Italian peninsula can be affected by Saharan dust outbreaks, which can contribute to the exceedance of the PM10 limit value. For this reason, it is mandatory to identify the quantitative amount of relevant mineral dust events. Several methods and techniques have been proposed to identify and quantify the amount of mineral dust to PM10 concentration, using both experimental techniques and numerical models. Numerical models can simulate the dynamic of long-­‐range transport of mineral dust and the consequent deposition, while the measurement of the concentrations of soil dust elements can be used to quantify the effective amount of Saharan dust in PM10 samples. During the summer of 2014, the University of Florence and INFN carried out a specific field campaign, in the framework of PATOS project [1], allowing the assessment of the mineral dust contribute to PM10 concentrations. In particular, the concentrations of all the main soil dust elements were measured by the PIXE technique. This campaign included daily measurements, on alternate days, for the whole period and hourly measurements for two weeks. The PM samplings were performed in two sites: one along the Tuscany coast (Livorno-­‐La Pira) and the second at a hinterland site (Pistoia-­‐Montale). The characterization of the main Saharan dust outbreaks affecting the Tuscany Region during the same period, has been conducted using the SPARTA model chain [2], developed by the LaMMA Consortium, as designated by the Tuscany Regional Government. SPARTA is based on the meteorological model WRF-­‐ARW and on the chemical model CAMx, using CHIMERE boundary conditions. This modelling system is able to provide a three dimensional description of the dynamic evolution of the dust episode. In such a way, it is possible to recognize, in a more efficient way with respect to using the back-­‐trajectories or satellite images, the episodes involving the lower part of the atmosphere, near the soil, contributing to the increase of PM10 concentration. The joined use of a numerical model and in-­‐situ measurements provides a complete characterization of the Saharan dust outbreaks, which includes both the meteorological and dynamical aspects as well as the quantification of the impact on PM10 at the ground level. The comparison between simulations and measurements, during the studied period, reveals a good agreement, properly detecting all the high concentration episodes, both on hourly and daily bases.