Verification of different techniques for the measurement of marine aerosols in coastal areas

Abstract

processes as well as in the production and dynamics of marine aerosols. Marine aerosol concentrations are significantly higher in such areas. Aerosols, in the zone of direct interaction between the air and the ocean surface are characterized by rapid time-space changes of concentrations. The continual changes in aerosol concentrations are due both to external changes, such as variations in particle input, and internal changes like coalescence, coagulation and evaporation. These processes result in the variations of aerosol sizes, which also influences particle removal from the marine boundary layer. This means that changes in aerosol concentration in the marine boundary layer are connected to with the changes in the spectrum of marine aerosol size distribution functions. This spectrum is complex and depends strongly on weather conditions in the marine boundary layer. In order to determine aerosol size distribution and concentration six cascade impactors, a particle measurement system and a lidar were employed. The impactor is an inertial separator of particles whose separation effectiveness depends on the nozzle diameter and the Reynolds number. It was confirmed that the effectiveness of catching particles from the size range r E [ 1, 10 pm] and larger is loaded with an error of not greater than 24.5 %. A particle measurement system CSASP-100~HV(Sp) is a water droplet spectrometer which operates on the principle that the light scattered by a particle within a high intensity laser beam is directly a function of its size. Particles produce pulses of radiant energy during transit through the laser beam. These light pulses are sensed by detectors and are read by two peak readers. System CSASP- 1 00-HV provides means of resolving and sizing particles in an in-situ mode. The CSASP- 1 00-HV is capable of sizing particles into fifteen size classes (size ranges: 247 urn; 2-32 pm; 1-16 pm; 0.5-8 pm). In the lidar method, laser pulses are transmitted into the atmosphere and backscattered radiation is collected by an optical telescope and detected. Mie scattering from particles and Raleigh scattering from molecules provide strong signals observed in backscattering in lidar sounding of the free atmosphere. These scattering processes are elastic, i.e.. the scattered photons have the same frequency as the incoming light. Lidar method allows for remote measurements of vast areas which range is closely related to the platform arrangement for the