Saharan Dust Modeling Over the Mediterranean Basin and Central Europe: Does the Resolution Matter?

Abstract

The Mediterranean Basin is frequently affected by desert dust outbreaks coming from the north of Africa. The presence of this type of particulate matter (PM) joint to others (in particular, anthropogenic pollution from the intense human activities) makes the air quality over this region a worrying issue. In this sense, an accurate characterization of the dust transport is essential. This study tries to shed some light on the sensitivity of dust modeling to the spatial resolution by using the online integrated meteorological-chemical model (WRF-Chem). Three simulations only differing on spatial resolution (D1 at 1.32°, D2 at 0.44° and D3 at 0.11°), during a representative omega-blocking situation over Europe causing Saharan dust transport over the Mediterranean and central Europe were evaluated against MODIS and AERONET. This evaluation revealed an improvement in the model AOD representation when resolution becomes finer, specially over the Saharan desert dust affected area. These discrepancies between resolutions could be attributed to changes both in thermodynamics and dynamics, since AOD is sensitive to aerosol mass, size distribution and water uptake. Relative humidity (RH) and PM-ratio (PM2.5/PM10) present non-local differences due to the increase of the resolution as a consequence of changes in the long-range transport spatial pattern. Henceforth, the comparison of wind speed and direction, geopotencial height and sea level pressure (SLP) against ERA5 data shows a better representation of the dynamical patterns when decreasing spatial resolution.