Comparison of EZLidar, MPL, and an elastic lidar for urban air quality applications

Nearly a year of coincident data in the Baltimore suburban area have been taken with three upward looking lidars. The project, called UMBC Measurements of Air Pollution (UMAP), allowed us to compare a Leosphere EZLidar operating at 355nm with a Sigmaspace Micropulse Lidar (MPL) and an elastic lidar called ELF, both operating in the green. The purpose of the comparison was to test the readiness and ease in utilization of the two commercial lidars for routine network deployment. There is intent on the part of the National Weather Service to move forward with a “Network of Networks” for lower tropospheric profiling with Mesoscale resolution and choice of a lidar in this network is an important decision. Each of the lidars can be used readily for time-height profiling of the PBL and routines have been tested on each for automated detection of PBL tops. The retrieval of extinction with the lidars to compare with Aerosol Optical Depth requires closure to obtain a realistic extinction to backscatter ratio at these wavelengths and the use of a coincident CIMEL sunphotometer allows a such an algorithm to be developed for each instrument. The extinction retrieval by closure appears to be more stable than the Klett algorithm deployed in the EZLidar distributed software. MPL co-alignment stability is an issue and the inclusion of a “mini-receiver” has merit for PBL applications. Since these systems were managed by new graduate students, we will make some observations on the system ease of deployment, ease of maintenance and level of documentation available for the commercial systems.

This work contributes to the CREST Lidar Network and GALION. Sponsorship by a NOAA Cooperative Agreement subaward from the City College of New York(SBCT 49100-00) and two NASA grants (NNS06AA02A and NNX08AO93G) is gratefully acknowledged.