Seasonal variability of aerosol optical properties observed by means of a Raman lidar at an EARLINET site over Northeastern Spain

Abstract

Abstract. The annual and seasonal variability of aerosol optical properties observed by means of a Raman lidar over Northeastern Spain has been assessed. The lidar representativeness has first been checked against sun-photometer measurements in terms of aerosol optical thickness. Then the annual cycle and the seasonal variability of the planetary boundary layer aerosol optical thickness and its fraction compared to the columnar optical thickness, the lidar ratio, the backscatter-relatedÅngström exponent and the planetary boundary layer height are analyzed and discussed. Winter and summer mean profiles of extinction, backscatter and lidar ratio retrieved with the Raman algorithm are presented. The analysis shows the impact of most of the natural events (Saharan dust intrusions, wildfires, etc.) and meteorological situations (summer anticyclonic situation, the formation of the Iberian thermal low, winter long-range transport from North Europe and/or North America, re-circulation flows, etc.) occurring in the Barcelona area. A detailed study of a special event including a combined intrusion of Saharan dust and biomass-burning particles proves the suitability of combining the retrieval of aerosol optical properties from Raman and pure elastic lidar measurements to discriminate spatially different types of aerosols and to follow their spatial and temporal evolution.

Separation of the optical and mass features of particle components in different aerosol mixtures by using POLIPHON retrievals in synergy with continuous polarized Micro-Pulse Lidar (P-MPL) measurements

“…In addition, AERONET AEx varies between 1.25 and 1.55 before 12:00 UTC (see Fig. 5a), indicating rather moderate AEx values compared to higher fresh smoke values (∼ 2.00), as also measured by Sicard et al (2011) in Barcelona. Hence, the value of δ SM = 0.15 reflects a mixing state of biomassburning particles but not necessarily with dust.…”

“…The typical background aerosol is a mixture of pollution particles with a minor contribution of marine aerosols, but this is only predominant under particular clean conditions. Other aerosol types, such as desert dust, fire smoke and pollen are also frequently found (Sicard et al, 2011). BCN is a well-established EAR-LINET station, and a relatively new MPLNET site, where a polarized Micro-Pulse Lidar (P-MPL) has been in routine operation since 2014.…”

Origin and pathways of the mineral dust transport to two Spanish EARLINET sites: Effect on the observed columnar and range-resolved dust optical properties

“…The radiation backscattered by the atmosphere is collected by a 38-cm diameter, 4-m focal length Cassegrain telescope and is guided by an optical fiber bundle to the wavelength separation unit (polychromator), where it is directed to the photodetectors (photomultiplier tubes for the 355-nm and the 532-nm wavelengths, and an avalanche photodiode for the 1064-nm wavelength) converting the optical signal at the corresponding wavelength into an electrical signal being sampled and stored for later analysis. The system has also Raman channels able to measure the radiation of the Raman vibrational-rotational spectrum scattered by atmospheric N 2 at 387 nm (excitation at 355 nm) and at 607 nm (excitation at 532 nm), as well as the radiation of the Raman vibrational-rotational spectrum scattered by water vapor (Kumar et al, 2011). This channels are not used in the present study.…”

“…The Saharan dust aerosol properties and their spatial and temporal variability over the Iberian Peninsula during the dust events have already been studied in recent years (Alados-Arboledas et al, 2003Lyamani et al, 2005Lyamani et al, , 2006aLyamani et al, , b, 2008Elias et al, 2006;Mona et al, 2006; Perez *Manuscript Click here to view linked References Dıaz et al, 2007;Guerrero-Rascado et al, 2008Cachorro et al, 2008;Sicard et al, 2011;Perez-Ramirez et al, 2012;Valenzuela et al, 2012;Navas-Guzman et a., 2013).…”

Performance Evaluation of the Boundary-Layer Height from Lidar and the Weather Research and Forecasting Model at an Urban Coastal Site in the North-East Iberian Peninsula

“…They comprise both objective and subjective methods: objective methods consist of various forms of derivative methods (Flamant et al 1997;Sicard et al 2006Sicard et al , 2011, wavelet analysis methods (Baars et al 2008;Gan et al 2011), the threshold method (Melfi et al 1985;Boers and Eloranta 2006), and the variance method (Menut et al 1999;Hennemuth and Lammert 2006). Visual inspection methods (Quan et al 2013) are infrequently used as a subjective approach, which adds levels of ambiguity that may possibly lead to poor results.…”