New Accurate Low-Cost Instrumentation for Obtaining Aerosol Optical Properties (UV to NIR) and Trace Gas Absorption Needed for Atmospheric Corrections

Jay R Herman, GSFC, jay.r.herman@nasa.gov (Presenting)
Nicholas A Krotkov, UMBC, nickolay.a.krotkov@nasa.gov
Alexander Cede, U of MD, alexander.cede@nasa.gov

We have recently developed accurate low-cost spectrometer systems that can determine aerosol optical depth and absorption from 300 to 900 nm in steps of 1 nm and trace gas absorption (e.g., NO2) throughout each clear-sky day. The small portable PAN-1 trace gas spectrometer system 300 – 525 nm (0.5 nm resolution) has been deployed at GSFC and used on field campaigns for the past year where it has been validated against other instrumentation. The new aerosol spectrometer CLEO is based on the shadowband technique, and has just been deployed at GSFC starting in March 2008. The methods are reviewed and data presented that show the accuracy (0.1 DU = 2.67x10^15 molecules/cm2) and precision (0.01 DU) for trace gas amounts compared to typical tropospheric amounts of 0.3 to 0.5 DU. The CLEO aerosol optical depth accuracy should be comparable to AERONET, but with continuous and extended wavelength range, and, for aerosol absorption, sensitivity to smaller amounts of aerosol. A filter-based version of the commercial UV shadowband can retrieve absorption coefficients at optical depths of 0.1 in the visible and UV, and agrees with AERONET retrievals at 443 nm.