Hi Nick,
We sadly don't have an official distribution mechanism for the ADF obs data yet given that we are still working on building up the datasets themselves. However, if you have access to any of the NCAR machines then you should be able to copy/download the ADF obs datasets we have so far, which are all located here:
/glade/work/nusbaume/SE_projects/model_diagnostics/ADF_obs
Of course if you don't have access then please let me know, and I can see about making the public accessibility of the obs a high priority for the development team.
Thanks, and have a great day!
Jesse