The satellite-based remote sensing of particulate matter (PM) in support to urban air quality: PM variability and hot spots within the Cordoba city (Argentina) as revealed by the high-resolution MAIAC-algorithm retrievals applied to a ten-years dataset

DELLA CECA, L; BARNABA, F. ; LYASPUTIN, A; CARRERAS, H

Viena

Congreso; European Geosciences Union; 2016

Particulatematter (PM) is one of the major harmful pollutants to public health and theenvironment [1]. In developed countries, specific air-quality legislationestablishes limit values for PM (e.g., PM10. PM2.5) to protect citizen?s health(e.g., European Commission Directive 2008/50, US Clean Air Act). Extensive PMmeasuring networks therefore exist in these countries to comply with thelegislation. In less developed countries air quality monitoring networks arestill scarce and satellite-based datasets could represent a valid alternative tofill observational gaps. The main PM(or aerosol) parameter retrieved from satellite is the ?aerosol optical depth?(AOD), an optical parameter quantifying the aerosol load in the wholeatmospheric column. Datasets from the MODIS sensors on board of the NASAspacecrafts TERRA and AQUA are among the longest records of AOD from space. However,although extremely useful in regional and global studies, the standard 10 km-resolutionMODIS AOD product is not suitable to be employed at the urban scale. Recently,a new algorithm called Multi-Angle Implementation of Atmospheric Correction(MAIAC) was developed for MODIS, providing AOD at 1 km resolution [2]. In this work,the MAIAC AOD retrievals over the decade 2003-2013 were employed to investigatethe spatiotemporal variation of atmospheric aerosols over the Argentinean cityof Cordoba andits surroundings, an area where a very scarce dataset of in situ PM data isavailable. The MAIAC retrievals over the city were firstly validated using a?ground truth? AOD dataset from the Cordobasunphotometer operating within the global AERONET network [3]. This validationshowed the good performances of the MAIAC algorithm in the area. The satellite MAIACAOD dataset was therefore employed to investigate the annual, seasonal andmonthly trends of particulate matter in the Cordoba city. The annual trend showed amarked increase of AOD over time, particularly evident in some areas of thecity (hot spots). These hot spots were put in relation with changes invehicular traffic flows after the construction of new roads in the urban area.The monthly-resolved analysis showed a marked seasonal cycle, evidencing theinfluence of both meteorological conditions and season-dependent sources on theAOD parameter. For instance, in the Cordoba rural area an increase of the AODsignal is observed during March-April, which is the soybean harvesting period,the main agricultural activity in the region. Furthermore, higher AOD signalswere observed in the vicinity of main roads during summer months (December toFebruary), likely related to the increase in vehicular traffic flow due totourism. Long-range transport is also shown to play a role at the city scale,as high AODs throughout the study area are observed between August andNovember. In fact, this is the biomass-burning season over the Amazon regionand most of South America, with huge amountsof fire-related particles injected into the atmosphere and transported acrossthe continent [4].