ATMOSPHERIC TURBIDITY ANALYZED BY MEANS OF STANDARDIZED LINKES TURBIDITY FACTOR

The concept of standardized Linke's turbidity factor T-LAM2 allows the conversion of the usual T-L values, which exhibit virtual diurnal var iations into new ones, which are strictly representative of the atmosp heric turbidity caused by both water vapor and aerosol. The T-LAM2 are T-L values reduced at relative air mass 2 on the basis of a spectral T-L model recently developed. The T-LAM2 values are used to analyze th e variations of atmospheric turbidity in a steep-sided urban alpine va lley over a 3-year period. It appears that the dependence of the turbi dity on altitude is related to the annual cycle of high and low turbid ity periods. The T-LAM2 concept is required to detect the instantaneou s changes of atmospheric turbidity during the course of a given day, b ut it can also reveal the general trends in diurnal variations of turb idity, in relation to the season and to the altitude.