Received: 11 Apr 2014 – Discussion started: 11 Jun 2014
Abstract. This work examines the relationships between Aerosol Optical Depth (AOD) and Particulate Matter (PMX) parameters, based on long records (2003–2011) of two nearby sites from the AERONET and EMEP networks in the north-central area of Spain. The climatological annual cycle of PM10 and PM2.5 present a bimodality which might be partly due to desert dust intrusions, a pattern which does not appear in the annual cycle of the AOD. In the case of the AOD, this bimodality is likely to be masked because of the poor sampling of sunphotometer data as compared to PMX (67% of days against 90%), and this fact stresses the necessity of long-term observations. In monthly series, significant interannual variations are observed and most extrema coincide, however the bimodal shape remains relatively stable for PMX. Significant and consistent trends were found for both datasets likely associated to a decrease of desert dust apportionment until 2009. PM10 and AOD daily data are moderately correlated (0.56), a correlation improving for monthly means (0.70). In the case of strong desert dust events day-to-day correlation is not systematic, therefore an extensive analysis on PMX, fine-PM ratio, AOD and associated Ångström exponent (α) is carried out.
How to cite. Bennouna, Y. S., Cachorro, V., Burgos, M. A., Toledano, C., Torres, B., and de Frutos, A.: Relationships between columnar aerosol optical properties and surface particulate matter observations in north-central Spain from long-term records (2003–2011), Atmos. Meas. Tech. Discuss., 7, 5829–5882, https://doi.org/10.5194/amtd-7-5829-2014, 2014.