THE EFFECT OF METEOROLOGICAL PARAMETERS AND AEROSOL CONSTITUENTS ON VISIBILITY IN URBAN HONG-KONG

A study on the possible atmospheric factors reponsible for visibility reduction in Hong Kong has been carried out using time-matched sets of data on the important meteorological parameters and on the chemical s pecies in aerosol matter over the 1990-1992 period. Careful observatio ns on the correlations as well as rotated principal components obtaine d from the original and screened (< 80% RH) data sets suggest that (i) visibility is highest in the summer and lowest in the winter halves o f the year; (ii) mixing height is the most important meteorological va riable and (iii) ammonium-sulphate, nitrate and potassium are the prim ary chemical species, among those considered;that affect visibility. f t is suggested that sulphates and nitrates of ammonium formed through gas-to-particle conversion reactions, and a fine particulate component containing potassium, possibly from some unknown biomass combustion s ource(s) are involved in the visibility reduction through catering in the urban Hong Kong atmosphere. However, additional scattering by orga nics and absorption by elemental carbon from combustion of biofuels, e specially automotive (diesel) emission is quit: likely, and needs to b e investigated, as is the question of local and foreign contributions of pollutants to visibility reduction. (C) 1998 Elsevier Science Ltd. All rights reserved.