We have re-licensed NCO source code from GPL3 to 3-Clause BSD starting with Version 4.9.2. Why? To encourage wider adoption and support. Without institutional (i.e., federal agency) support, NCO development would crawl to a standstill. We are acceding to the preferences of our occasional sponsors (DOE, NASA, NSF) for permissive OpenSource licenses.
Version 4.9.2 contains many regridding fixes and features: Improved adoption has made the NCO weight-generator more robust. Its signature strengths are speed and ultra-high resolution support. It can create ~3 km global maps from in under an hour to and from some (not all) grids including FV physics grids (ne1024pg2), MPAS grids, and RLL grids. Problems remain, though ncremap also supports ESMF and TempestRemap so take your pick. Moreover the map checker, ncks --chk_map, produces improved metrics with fewer false alarms.