Four‐year aerosol observations with a Raman lidar at Thessaloniki, Greece, in the framework of European Aerosol Research Lidar Network (EARLINET)

Amiridis, Vassilis; Balis, D.; Kazadzis, Stelios; Bais, A. F.; Giannakaki, Elina; Papayannis, A.; Zerefos, C. S.

doi:10.1029/2005jd006190

Cited by 192 publications

(197 citation statements)

References 75 publications

(116 reference statements)

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“…More technical and measurement details concerning the LAP lidar system can be found in the literature Amiridis et al, 2005 In this study, we present lidar measurements performed over Thessaloniki, for cases when cirrus clouds were observed in the period [2000][2001][2002][2003][2004][2005][2006]. Fifteen cases of Raman (nighttime) measurements and thirty eight cases of daily measurements were found during the routine schedule of the measurements.…”

Section: Instrumentationmentioning

confidence: 99%

Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

Giannakaki¹,

Balis²,

Amiridis

et al. 2007

Atmos. Chem. Phys.

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Abstract. Optical and geometrical characteristics of cirrus clouds over Thessaloniki, Greece (40.6 • N, 22.9 • E) have been determined from the analysis of lidar and radiosonde measurements performed during the period from 2000 to 2006. Cirrus clouds are generally observed in a mid-altitude region ranging from 8.6 to 13 km, with mid-cloud temperatures in the range from −65 • to −38 • C. The cloud thickness generally ranges from 1 to 5 km and 38% of the cases studied have thickness between 2 and 3 km. The retrieval of optical depth and lidar ratio of cirrus clouds is performed using three different methods, taking into account multiple scattering effect. The mean optical depth is found to be 0.31±0.24 and the corresponding mean lidar ratio is 30±17 sr following the scheme of Klett-Fernald method. Sub-visual, thin and opaque cirrus clouds are observed at 3%, 57% and 40% of the measured cases, respectively. A comparison of the results obtained between the three methods shows good agreement. The multiple scattering errors of the measured effective extinction coefficients range from 20 to 60%, depending on cloud optical depth. The temperature and thickness dependencies on optical properties have also been studied in detail. A maximum mid-cloud depth of ∼3.5 km is found at temperatures around ∼−47.5 • C, while there is an indication that optical depth and mean extinction coefficient increases with increasing mid-cloud temperature. A correlation between optical depth and thickness was also found. However, no clear dependence of the lidar ratio values on the cloud temperature and thickness was found.

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Section: Instrumentationmentioning

confidence: 99%

Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

Giannakaki¹,

Balis²,

Amiridis

et al. 2007

Atmos. Chem. Phys.

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“…The aerosol mixture over Thessaloniki consists of several different types of aerosols (e.g. urban, continental, marine, dust) and its composition varies (Amiridis et al, 2005;Koukouli et al, 2006). This could lead to large variability of the SSA, even within the same day (e.g.…”

Section: The Role Of Ozone and Aerosols On Short-and Long-term Variabmentioning

confidence: 99%

Short- and long-term variability of spectral solar UV irradiance at Thessaloniki, Greece: effects of changes in aerosols, total ozone and clouds

et al. 2016

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Abstract. In this study, we discuss the short-and the longterm variability of spectral UV irradiance at Thessaloniki, Greece, using a long, quality-controlled data set from two Brewer spectrophotometers. Long-term changes in spectral UV irradiance at 307.5, 324 and 350 nm for the period 1994-2014 are presented for different solar zenith angles and discussed in association with changes in total ozone column (TOC), aerosol optical depth (AOD) and cloudiness observed in the same period. Positive changes in annual mean anomalies of UV irradiance, ranging from 2 to 6 % per decade, have been detected both for clear-and all-sky conditions. The changes are generally greater for larger solar zenith angles and for shorter wavelengths. For clear-skies, these changes are, in most cases, statistically significant at the 95 % confidence limit. Decreases in the aerosol load and weakening of the attenuation by clouds lead to increases in UV irradiance in the summer, of 7-9 % per decade for 64 • solar zenith angle. The increasing TOC in winter counteracts the effect of decreasing AOD for this particular season, leading to small, statistically insignificant, negative long-term changes in irradiance at 307.5 nm. Annual mean UV irradiance levels are increasing from 1994 to 2006 and remain relatively stable thereafter, possibly due to the combined changes in the amount and optical properties of aerosols. However, no statistically significant corresponding turning point has been detected in the long-term changes of AOD. The absence of signatures of changes in AOD in the short-term variability of irradiance in the UV-A may have been caused by changes in the single scattering albedo of aerosols, which may counteract the effects of changes in AOD on irradiance. The anticorrelation between the year-to-year variability of the irradiance at 307.5 nm and TOC is clear and becomes clearer as the AOD decreases.

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“…There are already a lot of studies on Saharan dust lidar ratios mostly based on Raman lidar observations (Mattis et al, 2002;Amiridis et al, 2005;Mona et al, 2006;Papayannis et al, 2008;Esselborn et al, 2009;Tesche et al, 2009bTesche et al, , 2011Groß et al, 2011;Preißler et al, 2013). For heavy dust loads the lidar ratio was typically in the range of 45-60 sr for western Saharan dust sources.…”

Section: Introductionmentioning

confidence: 99%

Middle East versus Saharan dust extinction-to-backscatter ratios

et al. 2015

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Abstract. Four years (2010Four years ( -2013 of observations with polarization lidar and sun/sky photometer at the combined European Aerosol Research Lidar Network (EARLINET) and Aerosol Robotic Network (AERONET) site of Limassol (34.7 • N, 33 • E), Cyprus, were used to compare extinctionto-backscatter ratios (lidar ratios) for desert dust from Middle East deserts and the Sahara. In an earlier article, we analyzed one case only and found comparably low lidar ratios < 40 sr for Middle East dust. The complex data analysis scheme is presented. The quality of the retrieval is checked within a case study by comparing the results with respective Raman lidar solutions for particle backscatter, extinction, and lidar ratio. The applied combined lidar/photometer retrievals corroborate recent findings regarding the difference between Middle East and Saharan dust lidar ratios. We found values from 43-65 sr with a mean (±standard deviation) of 53 ± 6 sr for Saharan dust and from 33-48 sr with a mean of 41 ± 4 sr for Middle East dust for the wavelength of 532 nm. The presented data analysis, however, also demonstrates the difficulties in identifying the optical properties of dust even during outbreak situations in the presence of complex aerosol mixtures of desert dust, marine particles, fire smoke, and anthropogenic haze.

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Four‐year aerosol observations with a Raman lidar at Thessaloniki, Greece, in the framework of European Aerosol Research Lidar Network (EARLINET)

Cited by 192 publications

References 75 publications

Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

Short- and long-term variability of spectral solar UV irradiance at Thessaloniki, Greece: effects of changes in aerosols, total ozone and clouds

Middle East versus Saharan dust extinction-to-backscatter ratios

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