The suffix .tar refers to the standard Tape Archive file format. In this context, it usually signifies a large, bundled dataset containing observations from:
You can find the most detailed technical descriptions and the full data archives on the CHEESEHEAD Field Project page hosted by NCAR's Earth Observing Laboratory. CHEESEHEAD - Earth Observing Laboratory Cheesehead.tar
Testing whether high-density observations can reduce the "energy balance closure" problem, where measured energy entering the system doesn't match energy leaving it. Accessing the Data and Papers The suffix