The Vertical Distribution of Aerosol in the Lower Atmosphere Observed by a Lidar

Abstract

The vertical structure of the aerosol content observed by a lidarin the lower atmosphere is to be related to the thermal structureof the atmosphere, but no definite relationship has yet been foundbetween lidar and radiosonde data in spite of many suggestions madeconcerning this subject since the advent of lidar. Some investigationis here made on it by the use of lidar data obtained only on cleardays with light winds.
Aerosol particles are found in late afternoon to be accumulatedby atmospheric convection in the upper levels (700-1,600 meters orso), of which the boundary is mostly determined by the maximummixing depth obtained with the help of the temperature profile givenby radiosonde ascent and the maximum surface temperature. Lidarobservations clearly visualize the atmospheric convection throughtracers of aerosol particles. Both in the morning and in early afternoonit is seen that the “plume” or “flare” is one of the main formsin the convection. The vertical distributions of aerosols both in themorning and in the afternoon are characterized and classified inview of the convection based on the lidar data.
Many discontinuities of lidar echoes are found to be presentthroughout the lower atmosphere in the form of either large layersor solitary patches ; they are considered to be important in the "layerreflection"in the microwave propagation.