07/10/2013
Vertical Distribution of Aerosol Optical Depth Climatology
Summary
One of the largest uncertainties in estimating the impact of aerosols on atmospheric radiative forcing and cloud-aerosol interactions is the lack of sufficient observational data describing vertical profiles of aerosol particles and aerosol optical depth (AOD). For the first time, a climatology of the vertical distribution of AOD was obtained from micropulse lidar observations for climatically different locations worldwide during a four-year period (2007–2010) at five different U. S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility sites. Observations came both from fixed sites (Southern Great Plains; Tropical Western Pacific at Darwin, Australia; and Alaska’s North Slope) and two ARM mobile facility sites (Graciosa Island in the Azores and Germany’s Black Forest). Most aerosols were found to be confined to 0–2 kilometers (approximately the planetary boundary layer region) at all sites; however, all sites exhibited measurable aerosols well above the mixed layer, with different height maxima. The entire dataset demonstrates large day-to-day variability at all sites. Clear seasonal variations in AOD profiles also exist for all five sites. These results from regular, extensive observations in diverse climate regimes are relevant to improved understanding of aerosol properties and boundary-layer dynamics, as well as improving global climate models by incorporating aerosol radiative effects. The scientific community will benefit from the night- and daytime availability of these results.
References
Kafle, D. N., and R. L. Coulter. 2013. “Micropulse Lidar-Derived Aerosol Optical Depth Climatology at ARM Sites Worldwide,” Journal of Geophysical Research – Atmospheres, DOI: 10.1002/jgrd.50536.