Aerosol model development for environmental monitoring in the coastal atmosphere surface layer

摘要

Extinction of radiation in the marine boundary layer is dominated by scattering and absorption due to atmospheric aerosol. It is known, that the extinction of optical radiation visible and near IR spectra in the marine surface layer is determined mainly by scattering and absorption atmospheric aerosol. It influences on a dependence of spectral transmission and extinction both natural, and artificial light that is of interest for a wide range of problems, in particular for radiating problems at studying laws of climate formation, and for lines of the applications connected to the forecast of a signal power in coastal conditions at an estimation of EO systems characteristics. This is important to optical retrievals from satellite, remote sensing at environmental monitoring, backscatter of light to space (including climate forcing), cloud properties etc. In unpolluted regions the greatest effects on near shore scattering extinction will be a result of sea-salt from breaking waves and variations in relative humidity. The role of breaking waves appears to be modulated by wind, tide, swell, wave spectra and coastal conditions. These influences will be superimposed upon aerosol generated by open ocean sea-salt aerosol that varies with wind speed. The focus of our study is the extinction and optical effects due to aerosol in a specific coastal region. This involves linking coastal physical properties to oceanic and meteorological parameters in order to develop predictive algorithms that describe 3-D aerosol structure and variability. The aerosol microphysical model of the marine and coastal atmosphere surface layer is considered. The model distinctive feature is parameterization of amplitude and width of the modes as functions of fetch and wind speed. In the paper the dN/dr behavior depending at change meteorological parameters, heights above sea level, fetch, wind speed and RH is show. On the basis of the developed model with usage of Mie theory for spheres the description of the last version of developed code MaexPro 5.0 (Marine Aerosol Extinction Profiles) for spectral profiles of aerosol extinction coefficients α(λ) calculations in the wavelength band, equal λ = 0.2 - 12 μm, with step Δλ= 0.0001 m is presented. Also α(λ) profiles for various wind modes (combinations X and U) calculated by MaexPro 5.0 code are given. Results of α(λ) profiles calculations are presented at change RH = 40 - 98 % and heights H = 0 - 25 m. The calculated spectrums of α(λ) profiles are compared with experimental data of α(λ) received by a transmission method in various geographical areas.