Automated aerosol retrieval algorithms for ARM Micro Pulse Lidars

The inclusion of Micro Pulse Lidar (MPL) units among those active remote sensors purchased and installed at Atmospheric Radiation Measurement (ARM) program sites worldwide has led to four temporally rich datasets representing three distinct geographical regions: a nearly six year dataset from the southern Great Plains site in north central Oklahoma, three years combined from tropical western Pacific sites at Manus and Nauru Islands and two years from the North Slope of Alaska site. Algorithm development at NASA/GSFC has yielded an automated aerosol optical property retrieval methodology tested in this presentation. Aerosol optical depths, boundary layer top heights, extinction cross sections and extinction-to-backscatter ratios (523 nm) are among the primary products available from MPL data. However, system calibration techniques initialize using independent radiometric measurements (e.g., from the CIMEL sun photometer or MFRSR) which are unavailable during the night. Therefore, we study proposed techniques overcoming these potential data gaps and permitting continuous accurate calculations. We sample cases extracted from a two month portion of the southern Great Plains dataset between late August and October ’98. Similar products calculated from ARM Raman Lidar data serve as comparison. Despite an appreciable wavelength difference (the Raman operates at 355 nm), a qualitative analysis is still feasible. Applied operationally by ARM a successful algorithm run both in real-time mode and on much of the historical MPL database would supply the community with an invaluable database for aerosol climatological study.