The Arctic Data Center is being migrated into a new environment these days. the migration will be finished before Summer. As part of the migration, the legacy interface available at http://arcticdata.met.no will be permanently closed (address to be redirected into this site). The harvesting interfaces have already been shut down and new harvesting interfaces are being implemented at https://adc.csw.met.no/. This is an pyCSW implementation supporting OGC CSW, OAI-PMH and OpenSearch.
We have discovered an issue with some records harvested from NILU/EBAS. We try to fix these issues in collaboration with NILU/EBAS. Direct download works fine, but OPeNDAP access to datasets doesn't work properly for the time being.