Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

Abstract

Abstract.We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company) covering the range from 300-1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain) of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on theÅngström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behavior of these estimations in each area of study.

Retrieval of the aerosol optical depth in the UV‐B at Uccle from Brewer ozone measurements over a long time period 1984–2002

“…In the past, many reports have been written on the retrieval of aerosol optical depth in the atmosphere and their properties [ King et al , 1980], [ Marenco et al , 1997], [ Alexandrov et al , 2001]. Some papers tried to evaluate the AOD of the atmosphere in the UV‐B and its variation with time [ Kirchhoff et al , 2001], to estimate the AOD in the UV [ Cachorro et al , 2002], or to correlate the general circulation of the atmosphere with the aerosol transport to forecast the time variation of the aerosol in the atmosphere in order to guide environmental protection policies [ Takemura et al , 2001]. Another way to study the AOD is to determine the aerosol single scattering albedo which is an important aerosol radiation parameter in determining surface UV irradiance [ Petters et al , 2003].…”

Spatial Variability and Radiative Impact of Aerosol along the Brahmaputra River Valley in India: Results from a Campaign

“…AE is useful to compare and characterize the wavelength dependence of AOD and columnar aerosol size distribution [39] [43]. A relative increase in the number of fine particles with respect to the coarse mode particles will result an increase in the value of AE and vice versa.…”

Comparative measurements of total ozone amount and aerosol optical depth during a campaign at El Arenosillo, Huelva, Spain

“…For direct spectra from LICOR and SPUV02, the comparison is more delicate, because LICOR has a very low resolution, and also because its results are not expected to be good below approximately 320 nm (Cachorro et al, 2002). The chosen common FWHM is 6 nm and the spectra are reconvoluted in the range 305-394 nm.…”