I can provide the following data for the science team:
daily (hourly) broadband solar radiation at ground measured with pyranometer separated for clear, broken cloudy and overcast sky conditions.
climatologies and trend analyses from 1960 to 1990 for US (with many gaps) and 1964 to 1990 for German stations (continuous)
data can be used to validate modelled trends of an direct or indirect aerosol effect on surface solar radiation from the 1960s to 1990s.
for data requests send an email to email@example.com I am planning to post it on a home page.
Beate G. Liepert
Lamont-Doherty Earth Observatory
of Columbia University New York
Palisades , New York 10964 , USA