Particulate matter (PM10 ) monitoring in South Tyrol, Italian Alps using MODIS satellite data

In 2008, the European Academy (EURAC) and the Autonomous Province of Bolzano started a research project to monitor air quality in South Tyrol: Near real time satellite data from the MODIS sensor and in-situ measurements from a state-of-the-art measurement network with 15 ground stations are integrated to produce daily air quality products. In this work, we discuss the applicability of satellite based aerosol retrievals for PM10 monitoring in a mountainous region. We present two different PM10 products generated at EURAC for the region of South Tyrol (satellite based PM10 maps and assimilated PM10 maps) and we describe the corresponding retrieval methods. Using in-situ PM10 data from 2007 and 2008 from all stations in South Tyrol, we found correlations between the NASA standard MODIS Aerosol Optical Depth (AOD) and in situ PM10 which are significant lower than correlations reported from other regions. In our study, a physical model which considers boundary layer height estimates from NWP data, has shown best agreement with observed ground PM10 (average correlation 0.49). The 2-sigma (95% probability) interval for the predicted PM values is rather large (average 45 mug/m 3). To better understand the origin of such high uncertainties and to verify our assumptions, we have conducted balloon soundings at one test-site in South Tyrol during a 10 days field campaign in winter 2010. The site is situated within an Alpine Valley. Vertical aerosol properties have been investigated up to four times per day, from ground level up to 800m height. Beside standard meteorological parameters, we have measured the aerosol number size distribution in ambient relative humidity conditions and dry air as well as the black carbon content.