Greenland datasets: support for temperature validation

[stephenprice]

Greenland datasets: We would eventually like to use observationally-based data to validate modeled internal and basal temperatures. Borehole temperatures are available for this, as discussed here, and a synthesis of basal temperature observations (frozen vs. thawed extent) are discussed here.

The internal temperature datasets point to these publications:
Clow et al.
Cuffey et al.
Johnsen et al.

The dataset for the estimated frozen vs. thawed extent can be found here.