Investigation of troposphric aeosols by multiwavelength Mie-Raman lidar

Abstract

Atmospheric aerosols affect the Earth’s radiation balance by absorbing or scattering the fluxes of solar or terrestrial radiation. This change leads to radiative forcing of the atmosphere. Scattering of the solar radiation by aerosols tends to cool the atmosphere and this is called the "aerosol direct effect". Aerosols modify the cloud properties effecting rainfall patterns and this is called the "aerosol indirect effect". Thus, aerosols cause global cooling. Aerosols also have negative effect on public health; inhaling aerosols results with chemicals entering the human body and deposited into lungs causing lung cancer, asthma, premature death and cardiovascular problems. Lidar is the acronym of "light detection and ranging", with a laser transmitter and a telescope receiver supplied with electronic and optical instruments. Aerosol optical and physical parameters and important atmospheric data about the clouds and water vapor can be calculated by analyzing aerosol extinction and backscattering coefficients which can be obtained by the remote sensing technology of lidars. For the purpose of investigating the aerosols, a Multiwavelength Mie-Raman lidar has been designed, developed and operated between 2009 and 2010. By this lidar, extinction and backscattering at multiple wavelengths were measured and converted to microphysical properties of aerosols by mathematical methods. The retrieved data contains size distribution, effective radius, volume, surface area and number density, complex refractive index, volume and particle polarization, water vapor mixing ratio. The ash plums from the Iceland volcanic eruption were detected and characterized.