NCO: Simpler and faster model evaluation by NASA satellite data via unified file-level netCDF and HDF-EOS data post-processing tools

The fidelity of geoscientific model results are increasingly evaluated by comparison to products derived from NASA satellite measurements. The satellite data are archived in HDF-EOS format, which is now a superset of the netCDF format employed by most geoscientific models. Putting NASA-generated (HDF-EOS) data and model-generated (netCDF) data on a common grid, in the same format, for numerical comparison can be arduous because of data format incompatibilities. Many researchers desire a common toolkit for both HDF-EOS and netCDF data that would 1.~simplify and accelerate the independent analysis of both data formats (HDF-EOS and netCDF), 2.~exploit the strengths of netCDF's underlying HDF data format with easy-to-use netCDF tools, 3.~ease evaluations of model predictions (in netCDF format) by NASA-generated data (in HDF-EOS format). We describe recent progress extending the netCDF Operators (NCO) to process netCDF and HDF-EOS datasets that use hierarchical groups. Utilizing groups to store ensembles of observations and predictions can vastly simplify and accelerate the characterization, evaluation, and intercomparison of multiple geophysical observations and simulations. We will illustrate our approach by showing how much easier it is to characterize, evaluate, and intercompare Earth System Model-simulated (CMIP5 archive) and NASA-retrieved snow cover and albedo trends (from MODIS/CERES) with the group and HDF-EOS ``aware'' NCO compared to previous methods.