Automated LIDAR Data Acquisition and Analysis System (ALDAAS) for simultaneous two-wavelength extinction measurements of clouds and aerosols near Manila Bay

Abstract

LIDAR, the acronym for Light Detection And Ranging, has been a versatile tool in studying the Earth. Atmospheric studies have improved a lot with the use of information obtained from LIDAR data. Cloud and aerosol microphysical properties are routinely retrieved from LIDAR data gathered with multiple wavelength LIDAR systems. Depolarization measurements yield the thermodynamic properties of these scatterers. Planetary boundary layer (PBL) or atmospheric boundary layer (ABL) data can also be derived from LIDARs.
This paper discusses the characteristics of the multiple wavelength depolarization LIDAR system of the Physics Department of De La Salle University. Further, we will present some of the simultaneous two-wavelength (1064 nm and 532 nm) LIDAR data gathered and processed utilizing the Automated LIDAR Data Acquisition and Analysis System (ALDAAS). We plot the time height-intensity (THI) profiles of the range-squared corrected signals (RSCS) and extinction coefficients calculated using the modified Klett inversion algorithm for the 1064 nm and 532 nm Nd:YAG laser wavelengths assuming a constant value for the extinction-to-backscatter ratio.
The Windows-based ALDAAS package was written using Borland C++ Builder version 4. Control of the digital oscilloscope settings and acquisition parameters were accomplished using ALDAAS through an RS232 interface. The user specified number of data files were gathered at one minute intervals. Further, ALDAAS can be used to process the data and plot them in either single profiles or THI plots of the altitude variation of the received signal, RSCS, extinction coefficient, and backscatter coefficient.