| << | Profiling of Aerosols | >> |
Abstract
We present measurements of the aerosol vertical profiles and sun photometer data obtained during dust outbreaks over the EARLINET multi-wavelength (355- 532-1064-387-607 nm) Raman lidar station in Athens (37°98' N, 23°77' E), Greece, from May to July 2008. The lidar aerosol profiles were obtained at three wavelengths (355-532-1064 nm) in the 0.8-6 km height region. More specifically, we present the mean vertical profiles (and the corresponding standard deviation) of the aerosol backscatter and extinction coefficient, and the lidar ratio obtained by the ground-based lidar over Athens. The sun photometer aerosol measurements were performed by a CIMEL instrument, that provides aerosol optical depth (AOD) data at eight wavelengths (340, 380, 440, 500, 675, 870, 1020 and 1640 nm) and the Ångström exponent-AE (á) values. Additionally, the inversion of the CIMEL data enabled us to retrieve the microphysical properties of aerosols during the dust events (i.e. effective radius, volume size distribution, fine and coarse mode fractions). Thus, during the dust events, the maximum AOD measurements obtained by CIMEL ranged from 0.75 (at 1640 nm) up to 0.95 (at 340 nm), while the minimum AE values were of the order of 0.1. In addition, we present a detailed analysis of a case study of a dust outbreak occurred on May 2008 over Athens, forecasted by the DREAM dust model and followed by the synergy of ground-based and spaceborne lidars (CALIPSO) and sun photometry (CIMEL). More specifically, we present the aerosol optical and microphysical properties during that strong dust event. We found that the aerosol loading forecasted by DREAM was of the order of 1.5-4.5 gr/m2, while the maximum value of the volume size distribution retrieved from the CIMEL data was of the order of 0.32 µm3/ µm2 (May 20, 2008) with a mean aerosol radius of 2 µm. The following days the aerosol radius ranged between 1-3 µm. On the other hand, the CALIPSO and the ground-based lidar aerosol profiles showed that the dust load was present from 1.5 up to 5 km height