aerosol optical depth at 550 nm (T. J. Crowley and M. B. Unterman 2013. Technical details concerning development of a 1200-yr proxy index for global volcanism. Earth System Science Data 5: 187-197; DOI: 10.5194/essd-5-187-2013)
This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-2025982, NTL LTER. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.